This document describes the fabrication and testing of a high-performance tandem organic solar cell with novel active layers. It utilizes a record-efficiency polymer, PBTI3T, in combination with other polymers like PTB7 and PSBTBT-Si to further enhance efficiency. Absorption spectra of the polymers show offset peaks that minimize spectral overlap when combined in a tandem device. Tandem devices were fabricated with PBTI3T and either PTB7 or PSBTBT-Si as the active layers. Results showed one of the highest open-circuit voltages reported and an overall power conversion efficiency above 6%, demonstrating the potential of tandem organic photovoltaics using high-efficiency polymers.
This document analyzes the absorption properties and I-V characterization of a dye sensitized solar cell using a natural Ruthenium dye extracted from fruits. Anees Ur Rehman et al. fabricated a DSSC using Ruthenium dye extracted from fruits as a sensitizer on a titanium dioxide layer. They measured the cell's short circuit current, open circuit voltage, fill factor, and efficiency, finding values of 11.52 mA/cm2, 0.70V, 0.61, and 4.47% respectively under 110 mW/cm2 illumination. The dye was found to absorb visible light well and support electron transfer at the semiconductor interface, demonstrating the potential of natural dyes as lower-
Exploiting the potential of 2-((5-(4-(diphenylamino)- phenyl)thiophen-2-yl)me...Akinola Oyedele
A comprehensive experimental study is reported on the optical and electrical characteristics of 2-((5-(4-
(diphenylamino)phenyl)thiophen-2-yl)methylene)malononitrile (DPTMM) when used as molecular donor
in an organic solar cell (OSC) device structure.
Design and Simulation of Dye Sensitized Solar Cell as a Cost-Effective Alt...Scientific Review SR
The continuous research in the area of renewable energy technology to substitute the unsustainable nature of fossil
fuel in terms of it future availability and negative environmental impact created by fossil fuel has ensure the explore
of solar energy as a good alternative. Dye sensitized solar cells (DSSCs) serve to be a good alternative means of
producing photovoltaic solar cell. This work reports the working principle and construction process of dye-sensitized
solar cell. A synthesized dye (Ruthenium oxide) and an iodide electrolyte were used for better performance based on
already researched work. Also, this work reports the evaluation process with results recorded by the produced solar
cell within 6:00am (GMT) and 6:00pm (GMT) for selected days. The results from the evaluation process show a
better performance of a dye-sensitized solar cell in low and normal sunny day. The solar cell has a good performance
at 12:00noon with a 0.5V output.
This document describes research on using p-type transparent conducting oxides (p-TCOs) as protection layers for n-type semiconductor photoanodes used in solar water splitting devices. Specifically, it investigates using nickel cobaltite (NiCo2O4) as the p-TCO layer deposited on n-type silicon (n-Si) and indium phosphide (n-InP) photoanodes. Key findings include:
1) NiCo2O4 functions as both a selective hole contact and corrosion protection layer, allowing for stable water oxidation.
2) A 40nm NiCo2O4 layer provides acceptable corrosion protection and optical transparency for the photoanodes.
3)
Nanostructured conducting polymers for energy applications towards a sustaina...Science Padayatchi
This document reviews the synthesis and applications of conducting polymer nanostructures (CPNs). It discusses how CPNs have superior properties compared to bulk polymers for energy applications due to their nanoscale size, including higher electrical conductivity and surface area. The review covers template-based and template-free methods for synthesizing CPNs, focusing on hard-template, soft-template, and liquid crystalline approaches. It also discusses characterization techniques and applications of CPNs in areas like energy storage, conversion, and electrocatalysis. In conclusion, the review provides an overview of how CPNs can be used in technologies like fuel cells, photocatalysis, supercapacitors and batteries.
This paper presents a Dye sensitized solar cell (DYSSC), which is called as future generation solar cell. It is a
new class of green photovoltaic cell based on photosynthesis principle in nature. DYSSCs are fabricated using
two different natural dyes as sensitizers, which extracted from the materials existing in nature and our life, such
as flowers, leaves, fruits, traditional Chinese medicines, and beverages. The use of sensitizers having a broad
absorption band in conjunction with oxide films of nanocrystalline morphology permits to harvest a large
fraction of sunlight. There are good prospects to produce these cells at lower cost and much better efficiency
than conventional semiconductor devices by introducing various chemical and natural dyes. DYSSC are
implemented with simple and new technique to overcome the energy crisis and excess cost of semiconductor
solar cells.
Structure, Morphology & Infrared Spectroscopic Characterization of Ga (2x+2) ...IOSR Journals
This document summarizes a study that characterized the structure, morphology, and infrared spectroscopic properties of Ga(2x+2)NFe2(49-x)O3 ferrite synthesized using the sol gel technique. X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) were used to analyze the size, type of bonding, and surface properties between the compounds. The results agreed with previous literature. GaN was used as a dopant for x=1 and x=5 in the formula to introduce its semiconducting properties into the ferrite system and study the effects.
The document summarizes research on the effects of ion irradiation and high temperature annealing on nanocrystalline graphene grown directly on quartz and sapphire substrates. It finds that nanocrystalline graphene can withstand fairly high doses of ion irradiation without losing conductivity, but at higher doses it rapidly becomes insulating. Annealing can restore the conductivity of irradiated graphene. Ion irradiation also enhances graphene's adhesion to substrates and increases the substrate's ability to nucleate graphene deposition. These effects could enable new methods for patterning and imprint lithography of graphene on insulating substrates.
This document analyzes the absorption properties and I-V characterization of a dye sensitized solar cell using a natural Ruthenium dye extracted from fruits. Anees Ur Rehman et al. fabricated a DSSC using Ruthenium dye extracted from fruits as a sensitizer on a titanium dioxide layer. They measured the cell's short circuit current, open circuit voltage, fill factor, and efficiency, finding values of 11.52 mA/cm2, 0.70V, 0.61, and 4.47% respectively under 110 mW/cm2 illumination. The dye was found to absorb visible light well and support electron transfer at the semiconductor interface, demonstrating the potential of natural dyes as lower-
Exploiting the potential of 2-((5-(4-(diphenylamino)- phenyl)thiophen-2-yl)me...Akinola Oyedele
A comprehensive experimental study is reported on the optical and electrical characteristics of 2-((5-(4-
(diphenylamino)phenyl)thiophen-2-yl)methylene)malononitrile (DPTMM) when used as molecular donor
in an organic solar cell (OSC) device structure.
Design and Simulation of Dye Sensitized Solar Cell as a Cost-Effective Alt...Scientific Review SR
The continuous research in the area of renewable energy technology to substitute the unsustainable nature of fossil
fuel in terms of it future availability and negative environmental impact created by fossil fuel has ensure the explore
of solar energy as a good alternative. Dye sensitized solar cells (DSSCs) serve to be a good alternative means of
producing photovoltaic solar cell. This work reports the working principle and construction process of dye-sensitized
solar cell. A synthesized dye (Ruthenium oxide) and an iodide electrolyte were used for better performance based on
already researched work. Also, this work reports the evaluation process with results recorded by the produced solar
cell within 6:00am (GMT) and 6:00pm (GMT) for selected days. The results from the evaluation process show a
better performance of a dye-sensitized solar cell in low and normal sunny day. The solar cell has a good performance
at 12:00noon with a 0.5V output.
This document describes research on using p-type transparent conducting oxides (p-TCOs) as protection layers for n-type semiconductor photoanodes used in solar water splitting devices. Specifically, it investigates using nickel cobaltite (NiCo2O4) as the p-TCO layer deposited on n-type silicon (n-Si) and indium phosphide (n-InP) photoanodes. Key findings include:
1) NiCo2O4 functions as both a selective hole contact and corrosion protection layer, allowing for stable water oxidation.
2) A 40nm NiCo2O4 layer provides acceptable corrosion protection and optical transparency for the photoanodes.
3)
Nanostructured conducting polymers for energy applications towards a sustaina...Science Padayatchi
This document reviews the synthesis and applications of conducting polymer nanostructures (CPNs). It discusses how CPNs have superior properties compared to bulk polymers for energy applications due to their nanoscale size, including higher electrical conductivity and surface area. The review covers template-based and template-free methods for synthesizing CPNs, focusing on hard-template, soft-template, and liquid crystalline approaches. It also discusses characterization techniques and applications of CPNs in areas like energy storage, conversion, and electrocatalysis. In conclusion, the review provides an overview of how CPNs can be used in technologies like fuel cells, photocatalysis, supercapacitors and batteries.
This paper presents a Dye sensitized solar cell (DYSSC), which is called as future generation solar cell. It is a
new class of green photovoltaic cell based on photosynthesis principle in nature. DYSSCs are fabricated using
two different natural dyes as sensitizers, which extracted from the materials existing in nature and our life, such
as flowers, leaves, fruits, traditional Chinese medicines, and beverages. The use of sensitizers having a broad
absorption band in conjunction with oxide films of nanocrystalline morphology permits to harvest a large
fraction of sunlight. There are good prospects to produce these cells at lower cost and much better efficiency
than conventional semiconductor devices by introducing various chemical and natural dyes. DYSSC are
implemented with simple and new technique to overcome the energy crisis and excess cost of semiconductor
solar cells.
Structure, Morphology & Infrared Spectroscopic Characterization of Ga (2x+2) ...IOSR Journals
This document summarizes a study that characterized the structure, morphology, and infrared spectroscopic properties of Ga(2x+2)NFe2(49-x)O3 ferrite synthesized using the sol gel technique. X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) were used to analyze the size, type of bonding, and surface properties between the compounds. The results agreed with previous literature. GaN was used as a dopant for x=1 and x=5 in the formula to introduce its semiconducting properties into the ferrite system and study the effects.
The document summarizes research on the effects of ion irradiation and high temperature annealing on nanocrystalline graphene grown directly on quartz and sapphire substrates. It finds that nanocrystalline graphene can withstand fairly high doses of ion irradiation without losing conductivity, but at higher doses it rapidly becomes insulating. Annealing can restore the conductivity of irradiated graphene. Ion irradiation also enhances graphene's adhesion to substrates and increases the substrate's ability to nucleate graphene deposition. These effects could enable new methods for patterning and imprint lithography of graphene on insulating substrates.
Quantum dots for optoelectronic devices - phdassistancePhD Assistance
Nanometre-scale semiconductor chips have been imagined as next-generation technology with high functionality and convergence. Quantum dots, also known as artificial atoms, have special properties owing to their quantum confinement in all three dimensions. Quantum dots have a lot of interest in optoelectronic systems because of their special properties.
For decades, self-assembled nanostructures have been a topic of considerable concern and significance.
Learn More:https://bit.ly/3xJJAiZ
Contact Us:
Website: https://www.phdassistance.com/
UK: +44 7537144372
India No:+91-9176966446
Email: info@phdassistance.com
Recent progress in non platinum counter electrode materials for dye sensitize...Science Padayatchi
This document discusses recent progress in developing non-platinum counter electrode materials for dye-sensitized solar cells (DSSCs). It reviews various platinum-free materials that have been studied as alternatives to the traditionally used platinum counter electrodes in DSSCs. These include carbon-based materials like graphene and carbon nanotubes, conducting polymers, metal oxides and sulfides, transition metal nitrides and carbides, and composite materials. The document analyzes the advantages of these materials and their potential to lower the cost of DSSCs while maintaining good performance compared to expensive platinum electrodes.
Bathochromic shift in photo-absorption spectra of organic dye sensitizers thr...Narges Mohamadi
This document discusses the rational design of new organic dye sensitizers for dye-sensitized solar cells using computational methods. It begins by noting the increasing global energy demand and limitations of current energy sources. It then provides background on dye-sensitized solar cells and their advantages over traditional silicon solar cells. The objectives are to design dyes with broader absorption spectra extending into the near-infrared, reduced HOMO-LUMO gaps, and suitability for solar cells. Several dye structures are computationally modified and evaluated using density functional theory and time-dependent DFT to obtain optical and electronic properties. Promising new dyes with red-shifted absorption are identified.
Recent progress in non platinum counter electrode materials for dye sensitize...Science Padayatchi
Dye-sensitized solar cells (DSSCs) have gained increasing attention
with regard to photovoltaic devices, because of their low
cost and simple fabrication methods; they are mostly investigated
in indoor light-harvesting and portable applications. The
focus has been on three main parameters of photovoltaic devices,
that is, lifetime, and cost effectiveness. A DSSC consists of
four prominent components including a photoanode, a photosensitizer,
a redox electrolyte, and a counter electrode. The
counter electrode is a crucial component, in which triiodide is
reduced to iodide by electrons flowing through the external
circuit. An effective approach to improve the performance of
a counter electrode is to enhance the power conversion efficiency
and to reduce the cost of the device. Platinum-coated
conducting glass electrodes give the best performance, but
their high cost and the scarcity of platinum restricts large-scale
application in DSSCs. This has prompted researchers to develop
low-costing platinum-free electrodes for DSSCs. In this
review, we focus mainly on counter electrode materials for the
electrocatalytic redox reaction for the I¢/I¢
3 electrolyte, and
apart from this, other counter electrode materials for iodinefree
redox electrolytes are discussed. Different counter electrode
materials are highlighted in different categories such as
carbon materials, conducting polymers, oxide and sulfide materials,
transition-metal nitrides and carbides, and composite
materials. The stability of counter electrodes in DSSCs is also
presented.
This document summarizes manipulation strategies for two-dimensional amorphous nanomaterials (2D ANMs) to enhance their performance in electrochemical energy storage and conversion applications. It discusses two main categories of manipulation: 1) geometric configuration design, including spatial structure design (e.g. creating porous structures) and coordination environment design (e.g. defect creation); and 2) component interaction, including elemental doping/coupling and heterophase compositing. Recent examples manipulating 2D ANMs through these approaches for applications in batteries, supercapacitors and electrocatalysis are reviewed. The document concludes by discussing opportunities to further optimize manipulation of 2D ANMs.
h-BN has potential as an ideal dielectric material for 2D electronics. As a gate dielectric, h-BN provides improved carrier mobility and resists dielectric breakdown at high electric fields. When used as a substrate, h-BN enhances graphene conductivity and mobility while improving reliability by facilitating better heat dissipation than conventional dielectrics like SiO2. Overall, h-BN shows promise as an ubiquitous dielectric that can fulfill critical roles in 2D heterostructures and devices.
Vishal Shrotriya presented on low cost manufacturing of organic solar cells. He discussed Solarmer's development of roll-to-roll processing for high throughput, low temperature production of organic photovoltaic cells. Through new donor and acceptor materials, efficiencies over 8% have been achieved in single cells and modules. Testing has shown stability of over 2500 hours under continuous illumination. The talk outlined a roadmap for commercializing organic solar cell products, starting with applications in portable power and building integrated photovoltaics, with a potential market of hundreds of millions of dollars annually.
The document describes a study that uses design of experiments (DoE) to optimize slurry-cast cathodes for solid-state batteries. Various combinations of polymer binder type and content and conductive carbon additive type and content were tested as cathode composites. Electrochemical and mechanical performance data from the experiments were analyzed using statistical software to identify optimal combinations. The predictions identified polyisobutene as the best binder and vapor-grown carbon fibers as the best additive to maximize specific capacity. Hydrogenated nitrile butadiene rubber and vapor-grown carbon fibers provided the best combination to maximize capacity retention. Additional tests were conducted to understand changes during cycling.
This document is a report on plastic electronics and its applications submitted by Anurag Sharma and Saurav Suman to fulfill their Bachelor of Technology degree requirements. It discusses the basics of plastic electronics including organic vs inorganic materials, benefits of plastic electronics, and conductivity in plastics. It also covers manufacturing of plastic electronics and various applications such as OLEDs, organic transistors, solar cells, and more. The document includes declarations, acknowledgements, figures, and references.
This document discusses the fabrication of a dye-sensitized solar cell using extracts from unripe mango peels as the photosensitizer. Key points:
- A DSSC was fabricated using a platinum-coated counter electrode, titanium dioxide photoelectrode, iodolyte electrolyte, and a natural dye extracted from unripe mango peels.
- The energy conversion efficiency of the fabricated DSSC was measured to be 0.345%. I-V curves and absorption/transmittance spectra were also determined.
- Previous research has achieved efficiencies up to 11% using synthetic dyes or modifications to cell components, but natural dyes offer advantages of low cost,
The document summarizes a study that used a scanning Kelvin probe to characterize the surface modification of indium tin oxide (ITO) substrates with photopatternable silane adlayers. A photoreactive silane molecule containing an o-nitrobenzyl group was used to form self-assembled monolayers on ITO. UV light through a photomask was used to selectively remove regions of the silane layer, and changes in surface potential were detected using contact potential difference measurements from the scanning Kelvin probe. Additional characterization techniques including X-ray photoelectron spectroscopy and contact angle measurements were also used to analyze the modified surfaces.
Tuning the Ionic and Dielectric Properties of Electrospun Nanocomposite Fiber...IJERA Editor
This study reports the fabrication and characterization of electrospun polyvinylidene fluoride (PVdF)and
polyvinylpyrrolidone (PVP) nanofiber separators embedded with carbon black nanoparticles. Different weight
percentages (0, 0.25, 0.5, 1, 2, and 4wt%) of carbon black nanoparticles were dispersed in N, Ndimethylacetamide
(DMAC) and ethanol using sonication and high-speed agitations, and then PVdF and PVP
polymers were added to the dispersions prior to the mixing and electrospinning processes. The morphological,
dielectric constant, ionic conductivity, and surface hydrophobic properties of the PVdF/PVP nanofiber
separators were analyzed using various techniques. SEM micrograms showed that the fiber diameter was
around 100-200 nm. The ionic conductivity test clearly revealed a significant increase in conductivity valueof
4.28 x 10-4
S/cm for 4 wt. % carbon black loading. However, the contact angle values were decreased with
increasing weight percent of carbon black particles. The dielectric constant was increased with the carbon black
loading. As can be seen, overall physical properties of the nanocomposite separators were significantly
enhanced as a function of carbon black inclusions, which may be useful for supercapacitor separators and other
energy storage devices
The document discusses the development of novel biomaterials and devices for biooptoelectronics and biophotonics. Specifically, it examines using diazole acceptors and imidazoles in conjunction with standard and DNA-modified electrolytes. Testing showed the DNA electrolyte improved stability but yielded less beneficial changes to absorption spectra than the standard electrolyte. Prototype devices are being created to study color switching times using both electrolyte types.
Advantages and problems of perovskite solar cellalfachemistry
This article mainly introduces the advantages and problems of perovskite solar cell. Visit https://www.alfa-chemistry.com/products/perovskite-solar-cells-139.htm for more information.
Fabrication of (Polymer Blend-magnesium Oxide) Nanoparticle and Studying thei...journalBEEI
The document summarizes research on fabricating nanocomposites from a polymer blend of polyvinyl pyrrolidone (PVP) and carboxymethyl cellulose (CMC) with varying concentrations of magnesium oxide (MgO) nanoparticles. The optical properties of the nanocomposites, including absorbance, transmittance, absorption coefficient, refractive index, extinction coefficient, dielectric constant, optical conductivity, and energy bandgap were studied. The results showed that these optical properties generally increased with higher MgO nanoparticle concentration, while transmittance and energy bandgap decreased. The nanocomposites showed high absorbance in the UV region, indicating potential use for applications like radiation shielding.
Perovskite solar cells have increased in efficiency from below 5% in 2009 to over 20% in 2014, making them a promising solar cell technology. Researchers have discovered ways to improve perovskite solar cells using liquid inks, upconversion and downconversion techniques, light-absorbing dyes, quantum dots, organic and polymer materials, and adaptive and nanostructured surfaces. These techniques aim to lower the cost and increase the efficiency of solar cells.
Dye Sensitized Solar Cells- PhD Stage 3 SeminarNarges Mohamadi
This document discusses computational modeling of organic dye sensitizers for application in solar cells. It outlines the research question of how rational in silico design can be used to develop new organic dyes to increase photocurrent density by decreasing the optical band gap and extending light absorption into the near-infrared region. The document describes computational methods used, including density functional theory and time-dependent density functional theory to optimize dye structures, calculate frontier molecular orbital energies, and simulate UV-Vis absorption spectra. Selected results are presented on modifications made to an existing dye sensitizer to lower the band gap and shift absorption spectra bathochromically into the near-infrared. The overall outcome was successful design of new dyes with improved light absorption properties for potential
Charge Transport in organic semiconductorsTauqueer Khan
This document summarizes research on synthesizing cadmium telluride (CdTe) nanocrystals directly within a poly(3-hexylthiophene) (P3HT) matrix for use in photovoltaic devices. The in situ growth improves the polymer-nanoparticle interface facilitating efficient charge transfer. Spectral results suggest CdTe forms a charge transfer complex with P3HT via dipole-dipole interaction. Structural studies show CdTe facilitates charge transport pathways between polymer chains. Photovoltaic devices using P3HT-CdTe nanocomposites demonstrated enhanced current density and open circuit voltage compared to P3HT:PCBM devices due to increased energy level offset between donor and
The document discusses various applications of nanotechnology in renewable energy and energy storage. It describes how nanomaterials and structures can be used to improve solar cells, batteries, fuel cells, hydrogen production and storage, and enhance the efficiency of technologies like wind turbines. For example, it mentions that nanoparticles or nanowires in solar cell electrodes can increase surface area and improve energy capture. Nanotechnology also aims to develop cheaper catalysts and better electrolyte materials to advance fuel cells.
Organic solar cells the exciting interplay of excitons and nano-morphologyvvgk-thalluri
1) The document summarizes organic solar cells, which use a bulk heterojunction of a conjugated polymer donor and fullerene acceptor. When light is absorbed, excitons are formed that must dissociate at the donor-acceptor interface into free charges.
2) The bulk heterojunction morphology, consisting of an interpenetrating network of the donor and acceptor materials, allows more excitons to dissociate since the interface is throughout the volume. This leads to higher efficiencies than simple bilayer cells.
3) Efficiencies of over 6% have been achieved but further work is needed to improve stability and lower costs for organic solar cells to become commercially viable. Optimization of
This document summarizes a presentation on using carbon nanotubes in solar panel technology. It discusses how carbon nanotubes can improve the efficiency of solar cells compared to traditional organic solar cells. Carbon nanotubes are classified as single-walled or multi-walled nanotubes. Carbon nanotubes and a polymer called MEH-PPV-CN are used as materials in constructing a carbon solar cell. The cell works by generating electrons when exposed to light, which are transferred between energy bands and build up voltage. Adding carbon nanotubes can increase the cell's efficiency by improving light absorption and electron transport. Potential applications include using carbon nanotubes in the photoactive layer or as transparent electrodes.
Quantum dots for optoelectronic devices - phdassistancePhD Assistance
Nanometre-scale semiconductor chips have been imagined as next-generation technology with high functionality and convergence. Quantum dots, also known as artificial atoms, have special properties owing to their quantum confinement in all three dimensions. Quantum dots have a lot of interest in optoelectronic systems because of their special properties.
For decades, self-assembled nanostructures have been a topic of considerable concern and significance.
Learn More:https://bit.ly/3xJJAiZ
Contact Us:
Website: https://www.phdassistance.com/
UK: +44 7537144372
India No:+91-9176966446
Email: info@phdassistance.com
Recent progress in non platinum counter electrode materials for dye sensitize...Science Padayatchi
This document discusses recent progress in developing non-platinum counter electrode materials for dye-sensitized solar cells (DSSCs). It reviews various platinum-free materials that have been studied as alternatives to the traditionally used platinum counter electrodes in DSSCs. These include carbon-based materials like graphene and carbon nanotubes, conducting polymers, metal oxides and sulfides, transition metal nitrides and carbides, and composite materials. The document analyzes the advantages of these materials and their potential to lower the cost of DSSCs while maintaining good performance compared to expensive platinum electrodes.
Bathochromic shift in photo-absorption spectra of organic dye sensitizers thr...Narges Mohamadi
This document discusses the rational design of new organic dye sensitizers for dye-sensitized solar cells using computational methods. It begins by noting the increasing global energy demand and limitations of current energy sources. It then provides background on dye-sensitized solar cells and their advantages over traditional silicon solar cells. The objectives are to design dyes with broader absorption spectra extending into the near-infrared, reduced HOMO-LUMO gaps, and suitability for solar cells. Several dye structures are computationally modified and evaluated using density functional theory and time-dependent DFT to obtain optical and electronic properties. Promising new dyes with red-shifted absorption are identified.
Recent progress in non platinum counter electrode materials for dye sensitize...Science Padayatchi
Dye-sensitized solar cells (DSSCs) have gained increasing attention
with regard to photovoltaic devices, because of their low
cost and simple fabrication methods; they are mostly investigated
in indoor light-harvesting and portable applications. The
focus has been on three main parameters of photovoltaic devices,
that is, lifetime, and cost effectiveness. A DSSC consists of
four prominent components including a photoanode, a photosensitizer,
a redox electrolyte, and a counter electrode. The
counter electrode is a crucial component, in which triiodide is
reduced to iodide by electrons flowing through the external
circuit. An effective approach to improve the performance of
a counter electrode is to enhance the power conversion efficiency
and to reduce the cost of the device. Platinum-coated
conducting glass electrodes give the best performance, but
their high cost and the scarcity of platinum restricts large-scale
application in DSSCs. This has prompted researchers to develop
low-costing platinum-free electrodes for DSSCs. In this
review, we focus mainly on counter electrode materials for the
electrocatalytic redox reaction for the I¢/I¢
3 electrolyte, and
apart from this, other counter electrode materials for iodinefree
redox electrolytes are discussed. Different counter electrode
materials are highlighted in different categories such as
carbon materials, conducting polymers, oxide and sulfide materials,
transition-metal nitrides and carbides, and composite
materials. The stability of counter electrodes in DSSCs is also
presented.
This document summarizes manipulation strategies for two-dimensional amorphous nanomaterials (2D ANMs) to enhance their performance in electrochemical energy storage and conversion applications. It discusses two main categories of manipulation: 1) geometric configuration design, including spatial structure design (e.g. creating porous structures) and coordination environment design (e.g. defect creation); and 2) component interaction, including elemental doping/coupling and heterophase compositing. Recent examples manipulating 2D ANMs through these approaches for applications in batteries, supercapacitors and electrocatalysis are reviewed. The document concludes by discussing opportunities to further optimize manipulation of 2D ANMs.
h-BN has potential as an ideal dielectric material for 2D electronics. As a gate dielectric, h-BN provides improved carrier mobility and resists dielectric breakdown at high electric fields. When used as a substrate, h-BN enhances graphene conductivity and mobility while improving reliability by facilitating better heat dissipation than conventional dielectrics like SiO2. Overall, h-BN shows promise as an ubiquitous dielectric that can fulfill critical roles in 2D heterostructures and devices.
Vishal Shrotriya presented on low cost manufacturing of organic solar cells. He discussed Solarmer's development of roll-to-roll processing for high throughput, low temperature production of organic photovoltaic cells. Through new donor and acceptor materials, efficiencies over 8% have been achieved in single cells and modules. Testing has shown stability of over 2500 hours under continuous illumination. The talk outlined a roadmap for commercializing organic solar cell products, starting with applications in portable power and building integrated photovoltaics, with a potential market of hundreds of millions of dollars annually.
The document describes a study that uses design of experiments (DoE) to optimize slurry-cast cathodes for solid-state batteries. Various combinations of polymer binder type and content and conductive carbon additive type and content were tested as cathode composites. Electrochemical and mechanical performance data from the experiments were analyzed using statistical software to identify optimal combinations. The predictions identified polyisobutene as the best binder and vapor-grown carbon fibers as the best additive to maximize specific capacity. Hydrogenated nitrile butadiene rubber and vapor-grown carbon fibers provided the best combination to maximize capacity retention. Additional tests were conducted to understand changes during cycling.
This document is a report on plastic electronics and its applications submitted by Anurag Sharma and Saurav Suman to fulfill their Bachelor of Technology degree requirements. It discusses the basics of plastic electronics including organic vs inorganic materials, benefits of plastic electronics, and conductivity in plastics. It also covers manufacturing of plastic electronics and various applications such as OLEDs, organic transistors, solar cells, and more. The document includes declarations, acknowledgements, figures, and references.
This document discusses the fabrication of a dye-sensitized solar cell using extracts from unripe mango peels as the photosensitizer. Key points:
- A DSSC was fabricated using a platinum-coated counter electrode, titanium dioxide photoelectrode, iodolyte electrolyte, and a natural dye extracted from unripe mango peels.
- The energy conversion efficiency of the fabricated DSSC was measured to be 0.345%. I-V curves and absorption/transmittance spectra were also determined.
- Previous research has achieved efficiencies up to 11% using synthetic dyes or modifications to cell components, but natural dyes offer advantages of low cost,
The document summarizes a study that used a scanning Kelvin probe to characterize the surface modification of indium tin oxide (ITO) substrates with photopatternable silane adlayers. A photoreactive silane molecule containing an o-nitrobenzyl group was used to form self-assembled monolayers on ITO. UV light through a photomask was used to selectively remove regions of the silane layer, and changes in surface potential were detected using contact potential difference measurements from the scanning Kelvin probe. Additional characterization techniques including X-ray photoelectron spectroscopy and contact angle measurements were also used to analyze the modified surfaces.
Tuning the Ionic and Dielectric Properties of Electrospun Nanocomposite Fiber...IJERA Editor
This study reports the fabrication and characterization of electrospun polyvinylidene fluoride (PVdF)and
polyvinylpyrrolidone (PVP) nanofiber separators embedded with carbon black nanoparticles. Different weight
percentages (0, 0.25, 0.5, 1, 2, and 4wt%) of carbon black nanoparticles were dispersed in N, Ndimethylacetamide
(DMAC) and ethanol using sonication and high-speed agitations, and then PVdF and PVP
polymers were added to the dispersions prior to the mixing and electrospinning processes. The morphological,
dielectric constant, ionic conductivity, and surface hydrophobic properties of the PVdF/PVP nanofiber
separators were analyzed using various techniques. SEM micrograms showed that the fiber diameter was
around 100-200 nm. The ionic conductivity test clearly revealed a significant increase in conductivity valueof
4.28 x 10-4
S/cm for 4 wt. % carbon black loading. However, the contact angle values were decreased with
increasing weight percent of carbon black particles. The dielectric constant was increased with the carbon black
loading. As can be seen, overall physical properties of the nanocomposite separators were significantly
enhanced as a function of carbon black inclusions, which may be useful for supercapacitor separators and other
energy storage devices
The document discusses the development of novel biomaterials and devices for biooptoelectronics and biophotonics. Specifically, it examines using diazole acceptors and imidazoles in conjunction with standard and DNA-modified electrolytes. Testing showed the DNA electrolyte improved stability but yielded less beneficial changes to absorption spectra than the standard electrolyte. Prototype devices are being created to study color switching times using both electrolyte types.
Advantages and problems of perovskite solar cellalfachemistry
This article mainly introduces the advantages and problems of perovskite solar cell. Visit https://www.alfa-chemistry.com/products/perovskite-solar-cells-139.htm for more information.
Fabrication of (Polymer Blend-magnesium Oxide) Nanoparticle and Studying thei...journalBEEI
The document summarizes research on fabricating nanocomposites from a polymer blend of polyvinyl pyrrolidone (PVP) and carboxymethyl cellulose (CMC) with varying concentrations of magnesium oxide (MgO) nanoparticles. The optical properties of the nanocomposites, including absorbance, transmittance, absorption coefficient, refractive index, extinction coefficient, dielectric constant, optical conductivity, and energy bandgap were studied. The results showed that these optical properties generally increased with higher MgO nanoparticle concentration, while transmittance and energy bandgap decreased. The nanocomposites showed high absorbance in the UV region, indicating potential use for applications like radiation shielding.
Perovskite solar cells have increased in efficiency from below 5% in 2009 to over 20% in 2014, making them a promising solar cell technology. Researchers have discovered ways to improve perovskite solar cells using liquid inks, upconversion and downconversion techniques, light-absorbing dyes, quantum dots, organic and polymer materials, and adaptive and nanostructured surfaces. These techniques aim to lower the cost and increase the efficiency of solar cells.
Dye Sensitized Solar Cells- PhD Stage 3 SeminarNarges Mohamadi
This document discusses computational modeling of organic dye sensitizers for application in solar cells. It outlines the research question of how rational in silico design can be used to develop new organic dyes to increase photocurrent density by decreasing the optical band gap and extending light absorption into the near-infrared region. The document describes computational methods used, including density functional theory and time-dependent density functional theory to optimize dye structures, calculate frontier molecular orbital energies, and simulate UV-Vis absorption spectra. Selected results are presented on modifications made to an existing dye sensitizer to lower the band gap and shift absorption spectra bathochromically into the near-infrared. The overall outcome was successful design of new dyes with improved light absorption properties for potential
Charge Transport in organic semiconductorsTauqueer Khan
This document summarizes research on synthesizing cadmium telluride (CdTe) nanocrystals directly within a poly(3-hexylthiophene) (P3HT) matrix for use in photovoltaic devices. The in situ growth improves the polymer-nanoparticle interface facilitating efficient charge transfer. Spectral results suggest CdTe forms a charge transfer complex with P3HT via dipole-dipole interaction. Structural studies show CdTe facilitates charge transport pathways between polymer chains. Photovoltaic devices using P3HT-CdTe nanocomposites demonstrated enhanced current density and open circuit voltage compared to P3HT:PCBM devices due to increased energy level offset between donor and
The document discusses various applications of nanotechnology in renewable energy and energy storage. It describes how nanomaterials and structures can be used to improve solar cells, batteries, fuel cells, hydrogen production and storage, and enhance the efficiency of technologies like wind turbines. For example, it mentions that nanoparticles or nanowires in solar cell electrodes can increase surface area and improve energy capture. Nanotechnology also aims to develop cheaper catalysts and better electrolyte materials to advance fuel cells.
Organic solar cells the exciting interplay of excitons and nano-morphologyvvgk-thalluri
1) The document summarizes organic solar cells, which use a bulk heterojunction of a conjugated polymer donor and fullerene acceptor. When light is absorbed, excitons are formed that must dissociate at the donor-acceptor interface into free charges.
2) The bulk heterojunction morphology, consisting of an interpenetrating network of the donor and acceptor materials, allows more excitons to dissociate since the interface is throughout the volume. This leads to higher efficiencies than simple bilayer cells.
3) Efficiencies of over 6% have been achieved but further work is needed to improve stability and lower costs for organic solar cells to become commercially viable. Optimization of
This document summarizes a presentation on using carbon nanotubes in solar panel technology. It discusses how carbon nanotubes can improve the efficiency of solar cells compared to traditional organic solar cells. Carbon nanotubes are classified as single-walled or multi-walled nanotubes. Carbon nanotubes and a polymer called MEH-PPV-CN are used as materials in constructing a carbon solar cell. The cell works by generating electrons when exposed to light, which are transferred between energy bands and build up voltage. Adding carbon nanotubes can increase the cell's efficiency by improving light absorption and electron transport. Potential applications include using carbon nanotubes in the photoactive layer or as transparent electrodes.
Emerging Next Generation Solar Cells: Route to High Efficiency and Low Costijtsrd
Generation of clean energy is one of the main challenges of the 21st century. Solar energy is the most abundantly available renewable energy source which would be supplying more than 50% of the global electricity demand in 2100. Solar cells are used to convert light energy into electrical energy directly with an appeal that it does not generate any harmful bi-products, like greenhouse gasses. The manufacturing of solar cells is actually based on the types of semiconducting or non-semiconducting materials used and commercial maturity. From the very beginning of the terrestrial use of Solar Cells, efficiency and costs are the main focusing areas of research. The definition of so-called emerging technologies sometimes described as including any technology capable of overcoming the Shockley“Queisser limit of power conversion efficiency (33.7 percent) for a single junction device. In this paper, few promising materials for solar cells are discussed including their structural morphology, electrical and optical properties. The excellent state of the art technology, advantages and potential research issues yet to be explored are also pointed out. Md. Samiul Islam Sadek | Dr. M Junaebur Rashid | Dr. Zahid Hasan Mahmood"Emerging Next Generation Solar Cells: Route to High Efficiency and Low Cost" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-1 | Issue-4 , June 2017, URL: http://www.ijtsrd.com/papers/ijtsrd96.pdf http://www.ijtsrd.com/physics/other/96/emerging-next-generation-solar-cells-route-to-high-efficiency-and-low-cost/md-samiul-islam-sadek
Recent Developments in Organic Polymers Based- Photovoltaic Cellstheijes
In this review article, the uses of organic polymers to make photovoltaic cells have been discussed. The focus is mainly on discussing organic polymer based photovoltaic (OPVs) solar cells, the development of new device technologies and donor polymers that are being researched on. The recent development in this field has led to improved OPV performances with power conversion efficiencies as phenomenal as 9%. However for commercial application of this kind of OPVs, an improved device structure and cost effective processing methods are required. This article reports the polymer design criteria, energy level matching, nano-morphing of polymer/acceptor blend films and local dipole moments of the polymer chains that have been developed in the research that took place over the past 4 years. We emphasize the importance of developing new methods for designing polymers with improved physical properties and development of new technologies to fully understand the fundamentals of OPV mechanisms, which will help improve the power conversion efficiency of the OPV.
Impact of Gamma Irradiation on Structural and Dielectric Properties of CuI-PV...iosrjce
IOSR Journal of Applied Physics (IOSR-JAP) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
This document summarizes the research of Joe Rumer, focusing on organic electronics. It discusses how his research designs, models, and synthesizes new organic semiconductor materials for applications like flexible displays and solar cells. His work focuses on developing stable, high-performing n-type and p-type organic semiconductors. These materials are solution-processed and comprise conjugated small molecules and polymers to absorb light. One goal is improving transistor performance and operational lifetimes in commercial displays through enhanced stability and environmentally friendly chemistry.
This document summarizes the research of Joe Rumer, focusing on organic electronics. It discusses how his research designs, models, and synthesizes new organic semiconductor materials for applications like flexible displays and solar cells. His work focuses on developing stable, high-performing n-type and p-type organic semiconductors. These materials are solution-processed and comprise conjugated small molecules and polymers to absorb light. One goal is improving transistor performance and operational lifetimes in commercial displays through enhanced stability and environmentally friendly chemistry.
1) Carbon nanotube tissues were coated with a polymer electrolyte via electrodeposition to improve their performance as anodes in flexible lithium-ion microbatteries.
2) Cyclic voltammetry was used to deposit p-sulfonated poly(allyl phenyl ether) polymer electrolyte into the carbon nanotube tissues.
3) The polymer-coated carbon nanotube tissue delivered a higher reversible capacity of 750 mAh/g compared to 450 mAh/g for the uncoated tissue, maintaining higher capacity even at fast charge/discharge rates, demonstrating its potential for flexible lithium-ion microbatteries.
This document discusses organic solar cells, which convert light to electricity using conjugated polymers and molecules rather than traditional silicon materials. It provides background on the need for alternative energy sources due to growing energy demand and limited fossil fuels. Organic solar cells absorb light, transfer charges, transport the separated charges, and collect them. Researchers have achieved a new record efficiency of 15.6% for a graphene-based solar cell that uses titanium oxide, graphene, and perovskite, manufactured via low-temperature solution deposition. While organic solar cells offer advantages like lower costs and flexibility, their efficiency remains below silicon cells and they suffer from degradation. Further improving charge carrier transport and interface engineering is needed to enhance performance.
OFET Preparation by Lithography and Thin Film Depositions ProcessTELKOMNIKA JOURNAL
This document summarizes research on preparing an organic field-effect transistor (OFET) using lithography and thin film deposition processes. The key points are:
1. An OFET was prepared with a bottom contact structure using copper phthalocyanine as the active layer deposited via vacuum evaporation on a silicon substrate.
2. Lithography was used to pattern gold source and drain electrodes, followed by deposition of the copper phthalocyanine thin film.
3. Electrical characterization of the completed OFET showed current increasing with drain voltage and gate voltage, indicating p-type accumulation mode operation, though saturation was not observed possibly due to a high threshold voltage.
IRJET- Microbial Fuel Cell for Chemical Zone Waste Water AmbernathIRJET Journal
This document summarizes a study on using microbial fuel cells to generate electricity from wastewater. The study constructed microbial fuel cells with two chambers connected by a salt bridge, with a graphite anode in one chamber filled with wastewater and an aluminum cathode in the other filled with electrolyte. Testing of the fuel cells over 9 days using wastewater from two locations found maximum voltages of 1909mV and 1944mV. The document also reviews previous literature on microbial fuel cells and discusses factors that affect power generation as well as the materials, reactions, and methodology used in the study.
Infrared plastic solar cell @1000KV Technologies 90308448771000kv technologies
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Organic electronics such as organic LEDs (OLEDs) and organic photovoltaics (OPVs) offer advantages over traditional electronics like being lightweight, flexible, and having low-cost production. The document discusses the electronic structures of organic materials used in these applications and how they enable charge transport. It reviews the state-of-the-art in OLED and OPV technologies and processing techniques like solution processing and vapor deposition. Photocrosslinking is highlighted as a method to improve device performance. Challenges in improving material properties, device efficiencies, and reducing costs are also outlined.
This document summarizes a research paper on dye sensitized solar cells (DSSCs). It provides background on the development of DSSCs since 1991 and their advantages over traditional silicon solar cells in terms of lower cost and simpler preparation. However, liquid electrolytes used in early DSSCs limited long-term performance. Recent research has focused on improving electrolytes, particularly developing quasi-solid state electrolytes, to enhance photoelectric performance and stability for practical applications of DSSCs. The document reviews progress on quasi-solid state electrolytes and their advantages over liquid electrolytes for DSSCs.
201006 studies on low cost and safe lithium ion batteries for electric vehiclexizhixia
1. The document discusses developing low-cost and safe lithium-ion batteries for electric vehicles through employing a lithium cobalt nickel manganese oxide cathode material synthesized via a hydrothermal technique.
2. Initial studies synthesized and characterized a lithium manganese oxide cathode material and conducted electrochemical testing of coin cells.
3. Ongoing work includes further cathode material synthesis and characterization, battery assembly, and characterization of assembled batteries.
A view on Perovskite Solar Cells: An Emerging TechnologyIRJET Journal
The document discusses perovskite solar cells as an emerging solar technology, noting that perovskite cells offer higher efficiency and lower cost compared to traditional silicon solar cells. It describes the fabrication process, design implementation, manufacturing, and applications of perovskite solar cells. While perovskite cells currently have stability issues, the document argues that addressing these issues could allow perovskite technology to transform solar power deployment.
IRJET- Bioelectricity Production from Seafood Processing Wastewater using...IRJET Journal
This document summarizes a study on generating bioelectricity from seafood processing wastewater using a microbial fuel cell (MFC). The researchers constructed a dual-chamber MFC with a salt bridge separator and inoculated it with anaerobic sludge. They operated the MFC in batch mode, filling the anode chamber with seafood wastewater. The MFC generated a maximum voltage of 988 mV at 1000 ohms resistance, corresponding to maximum current density of 2996.664 mA/m2 and power density of 2960.704 mW/m2. The MFC achieved a 77.33% COD removal efficiency and 84.32% phosphate removal efficiency at a hydraulic retention time of
This thesis presents the design optimization of a solution-processed two-terminal perovskite-organic tandem solar cell. The objective is to design an optimized cell with low-cost roll-to-roll manufacturing and bandgap tunability. A transfer matrix method model is used to simulate the cell, achieving a short circuit current density of 13.78 mA/cm^2 and power conversion efficiency of 17.77%. Experimental validation of the model is presented. Future work includes fabricating and testing the proposed cell design.
1. A high-performance tandem organic solar cell with novel active layers providing visible
and near-IR spectrum absorption
Introduction
Faced with the combined threat of depleting non-renewable energy sources and their
disastrous impact on the planet’s ecosystem, the international community has realized the
urgency of developing clean, affordable, and convenient renewable energy sources.1
The sun
offers much more energy than humanity could ever use, giving solar power the potential to
outgrow competing clean energy sources. A harbinger of the viability of solar technology for
energy generation was the creation of efficient crystalline silicon solar cells at Bell Labs in the
1950s, a discovery which sparked the modern field of photovoltaic research. 2
Traditional silicon-based solar cells harvest energy through semiconductor physics,
where photonic energy drives charge separation at the junction of positively and negatively
doped silicon to create harvestable electric current. Solar cells made with elements in groups III-
V of the periodic table demonstrate the best efficiencies in crystalline photovoltaics, achieving
high power conversion efficiencies (PCE 25%).3
However, they remain expensive due to limited
sources for materials and complex fabrication processes.1
There has been remarkable
improvement in inorganic solar technology since the 1950s;4
the majority of recent
improvements in efficiency have come from devices employing multi-layer (tandem) device
architecture. Tandem device structure has shown success in inorganic photovoltaic research, and
has produced astronomical efficiencies in triple-junction GaInP/GaInAs/Ge solar cells (PCE ≈
41%).3
With a tentative promise to solve the problems of traditional solar cells based on
inorganic materials, organic photovoltaics (OPVs) have emerged as a viable technology for solar
1
2. energy production thanks to developments in conducting and semiconducting polymers.5
They
have recently shown promising results due to their relatively easy production and low application
costs, prompting intensive research to optimize OPVs for stability and efficiency. OPVs have
several advantages over conventional p/n junction crystalline silicon solar cells; they can be
made on flexible substrates, employ high-throughput printing techniques, provide wide chemical
engineering possibilities, and are environmentally sound due to carbon-based semiconducting
materials (conjugated organic polymers). Driven by the promise of low cost, large area solar cell
production using roll-to-roll techniques, solution processability has become a goal for OPV
research alongside the improvement of efficiency and durability.8
In this way, organic solar
systems would employ low installation costs and multi-surface compatibility to offset their
relative inefficiency. Thus OPVs reduce the initial investment necessary to implement solar
technology, and make solar power a more universally accessible renewable energy source.9-11
Traditional OPV devices are fabricated on top of a transparent conductive electrode,
usually indium tin oxide (ITO). Active layers consist of electron-rich organic semiconductors
that absorb light and generate electron-hole pairs, (excitons), paired with electron-deficient
organic materials that separate and transport the generated charges. Electron rich polymers (e.g.
PTB7) are known as “donor” polymers, and electron-deficient compounds (fullerene derivatives,
e.g. PC70BM) are referred to as acceptors.
Connected by a specially designed interlayer, tandem device structure utilizes a
combination of two active layers in series within one device, where each layer is responsible for
absorbing certain wavelengths of light — from visible to near infrared wavelengths for carefully
designed devices.17
— and providing additive voltage (Voc) without compromising current (Jsc)
loss compared to single cells.13-16
Since Hadipour et al. 18
first demonstrated a tandem OPV with
2
3. two different bandgap polymers, achieving an additive voltage of 1.4 V and a PCE of 0.7%,
tandem devices have attracted attention in the past years. In fact, tandem OPVs have recently
pushed the organic device record to PCE>10%, creating optimism in this emerging field. Despite
presenting an intriguing strategy for efficiency enhancement, only few successful tandem works
have been published due to several reasons, namely: 1. lack of efficient polymers for single cells;
2. significant overlap of absorption spectra between donor polymers; 3. lack of efficient
interlayer between the two sub-cells; 4. fabrication procedures compatible with the multilayer
structure. Thus research in the design of materials and device fabrication must be done for
further advancement of tandem OPV technology.
After gaining an operational understanding of OPV device theory and fabrication
technique through the optimization and testing of the novel polymer PBTI3T, which
demonstrates a record high efficiency of 8.7% for single-layer OPV (manuscript currently under
review), this project decided to utilize this material within a tandem structure in combination
with other high performance materials to further enhance OPV PCEs.
In this work, after achieving a record high efficiency of 8.7% for single-layered OPV
(manuscript currently under review), this project decided to implement the record efficiency
material in a tandem structure combined with other high performance active layer materials to
further enhance OPV PCEs. A few published low bandgap polymers are successfully
implemented in tandem device architecture. All of the polymers later introduced in this work are
implemented together for the first time as part of a tandem OPV structure. Engineering tandem
OPVs to harness their full potential introduces a new set of challenges to the designing of
organic devices. As the complexity of solution processed devices increases, controlling and
optimizing layer morphology, texture, exclusivity, charge transfer, and thickness becomes
3
4. difficult. Thus materials selection for this research was non-trivial and focused on bandgap
characteristics of the p-type donor polymers, macro and microscopic polymer characteristics, as
well as single-layer cell performance.21
Within its scope, this project achieved one of the highest Voc (>1.4V) in OPV literature
and an overall PCE of >6% in this work. These results exemplify the potential of tandem
organic devices employing next generation high efficiency (single junction device PCE >7%)
polymers. Additionally, this work leads to future paths of work for tandem device optimization
to achieve efficiencies near those of commercially available silicon-based solar devices, while
retaining the hallmark characteristics of OPVs.
Materials & Methods
Figure 1: (a) donor and acceptor compounds used in this study (b) donor/acceptor bandgap diagrams.
Materials choice for the construction of tandem devices in this research focused on an
unpublished novel high efficiency semiconducting polymer poly(bithiopheneimide-trithiophene)
(PBTI3T), used as a donor polymer in one active layer for all of the tandem cells produced. In
4
5. the first section of this tandem device study the polymer Poly[[4,8-bis [ (2- ethylhexyl) oxy]
benzo [1,2-b:4,5-b'] dithiophene-2,6- diyl] [3- fluoro- 2-[(2-ethylhexyl) carbonyl] thieno [3,4-b]
thiophenediyl]] (PTB7) 22
was chosen for the active layer complementary to PBTI3T. For the
second part of this study, poly(4,4-dioctyldithieno(3,2-b:2',3'-d)silole)-2,6-diyl-alt- (2,1,3-
benzothiadiazole)-4,7-diyl) (PSBTBT-Si)23
was chosen as the complementary active layer. Each
polymer was blended with the molecule [6,6]-phenyl C71-butyric acid methyl ester (PC70BM) to
form a photoactive layer. PC70BM is a derivative of the carbon buckminster fullerene family,
and is a well-established, widely used electron acceptor in most OPVs.5
The chemical structures
and energy alignment of these materials are shown in Figure 1.
Figure 2: Device fabrication procedure for tandem OPVs.
Incorporating these materials into the production of a tandem BHJ solar cell is a multi-
step process with layers deposited upon an indium tin oxide (ITO) coated glass substrate as
follows (Figure 2): a) spin coated 20 nm zinc oxide (ZnO); b) spin coated first polymer active
5
6. layer (AL1); c) 5 Å vapor-deposited layer of silver (Ag); d) spin coated ~40 nm layer of
PEDOT:PSS; e) second 5 Å vapor-deposited layer of silver (Ag); f) second spin coated layer of
ZnO; g) spin coated second polymer active layer (AL2); h) 7.0 nm vapor deposited molybdenum
oxide (MoO3);120 nm vapor deposited Ag electrodes.
For the fabrication of OPV devices, a 10 Ω/☐ pre-patterned ITO is used as substrate. It is
cleaned by sequential sonication in hexane, DI water, methanol, isopropanol and acetone, and
finally UV/ozone treated (Jelight Co.). The ZnO interfacial layer is fabricated by spin-coating at
5000 rpm for 30 seconds onto ITO substrate from a precursor solution prepared with 220 mg
zinc acetate, 62 mg ethanolamine in 2 ml 2-methoxy-ethanol after sufficient stirring. Electrical
contact areas on substrates are cleaned with isopropyl alcohol (IPA) for anode or cathode
deposition. Deposited ZnO is annealed on a hot plate set to 170o
C. Devices are then transferred
to glovebox under nitrogen vacuum. Active layers are prepared under N2 condition in solutions
of 8 mg/mL PBTI3T in chloroform, 10 mg/mL PTB7 in chlorobenzene, and 10 mg/mL
PSBTBT-Si in chloroform. PC70BM is subsequently added with a polymer:fullerene weight ratio
of 1:2, 1:1.5, and 1:1 for optimal performance, respectively. 2%, 3% and 3% 1,8-diiodooctane
(DIO) are added to PBTI3T, PTB7, and PSBTBT-Si solutions, respectively, as processing
additives to improve the resulting active layer film morphology. All solutions are stirred at 70o
C
for >2 hrs. In the fabrication of PBTI3T+PTB7 or PBTI3T+PSBTBT-Si tandem devices, first
layer of PBTI3T is spun cast at 4000-6000 rpm for 30 seconds and second layer of PTB7 or
PSBTBT-Si solution is spun at 1500 rpm for 30 seconds.
The interlayer between the two separate active layers consists of a thin layer o f Ag (5 Å),
m-PEDOT:PSS (~40 nm), a second layer of Ag (5 Å), and ZnO (20 nm). The m-PEDOT:PSS is
fabricated according to the procedure developed by Yang Yang et al.14
PSS (Mw=40,000) is
6
7. added into 2g of PEDOT:PSS solution to increase the interlayer conductivity. 0.5% by weight
TritonTM
is subsequently added as a surfactant to enhance the surface wettability of the solution
on top of the first active layer. The solution is spun cast at 5000 rpm for 30 seconds and annealed
at 150O
C for 5 min. A thin layer of 5 Å Ag is thermally deposited under ultrahigh vacuum prior
to the deposition of ZnO which is prepared under the same condition as the first interfacial layer.
After the deposition of the second layer, thin layers of 7.0 nm MoO3 and 140 nm of Ag
are then thermally evaporated through a shadow mask at ~10-6
Torr. For device characterization,
J-V characteristics are measured under AM1.5G light (100 mW/cm2) using the Xe arc lamp of a
Spectra-Nova Class A solar simulator. The light intensity is calibrated using an NREL-certified
monocrystalline Si diode coupled to a KG3 filter to bring spectral mismatch to unity. A Keithley
2400 source meter is used for electrical characterization. The area of all devices is 6 mm2, and
an aperture with size of 6 mm2 is used on top of cells during all measurements. EQEs are
characterized using an Oriel model QE-PV-SI instrument equipped with a NIST-certified Si
diode. Monochromatic light is generated from an Oriel 300W lamp source.
7
8. Figure 3: The structure of a finished tandem device and an actual finished tandem device.
Discussion, Results, and Illustration
Figure 4: (a) band alignment diagram (b) a representative current-voltage (J-V) curve.
8
9. The discussion of OPV devices begins with four basic processes within each cell: 1) light
absorption and exciton formation; 2) exciton migration to a donor/acceptor interface; 3) exciton
separation due to sufficient interfacial potential energy drop; 4) charge carrier transport to device
electrodes (Figure 4a). These essential processes drive materials and structural optimization for
OPVs, and the refinement of each step of solar energy generation is crucial to the development
of efficient single layer and tandem OPVs. Bandgap engineering is essential to the beginning of
tandem OPV discussion because it correlates directly to the defining characteristic of additive
voltages in multi-junction device structure. Polymer bandgap is defined as the energy difference
between a semiconducting polymer’s highest occupied molecular orbital (HOMO) and lowest
unoccupied molecular orbital (LUMO) (Figure 1b). In donor polymers, photons are absorbed and
provide the energy to promote electrons from the HOMO level to the LUMO level, forming a
bound electron-hole pair (an exciton). The exciton then diffuses to a donor/acceptor interface,
and separates due to the potential energy difference between the LUMO of the n-type acceptor
material and the LUMO of the donor polymer. The resulting free-charge carriers, electrons and
holes, can travel to their respective electrodes (Figure 4a). The difference in polymer HOMO and
PC70BM LUMO levels corresponds to the theoretical Voc of the device. Therefore, the lower the
HOMO levels of polymers, the higher the Voc that can be expected.
The efficiency of tandem PSCs has been hindered by the availability of suitable low
bandgap materials and spectrally-mismatched high bandgap materials. In an effort to optimize
the absorption and exciton formation characteristics of tandem OPVs, this project chose to
explore the compatibility of a previously published and well-tested low bandgap polymer,
PSBTBT-Si, and to continue the study of PTB7, along with this project’s novel high-bandgap
polymer, PBTI3T.
9
10. Figure 5: Images of polymer solutions without and with PC70BM, and their respective absorption spectra in
solution.
As a primary evaluation of the selected polymers’ compatibility, the materials were
prepared in solution with and without the addition of PC70BM, and tested for absorption.
Spectrum absorption mismatch between donor polymers in tandem OPVs is crucial to ensure the
additive voltage of active layers. This relationship is demonstrated by the measured absorption
curves of the polymers chosen for this study, which portray offset absorption spectra of ~500-
675 nm, ~550-750 nm, and ~575-825 nm for polymers PBTI3T, PTB7, and PSBTBT-Si,
respectively (Figure 5). In preliminary studies of this research, PBTI3T has achieved 8.7%
efficiency in a single-layer cell, and its demonstrated shorter-wavelength absorbance spectrum is
ideal for working in tandem with both PTB7 and PSBTBT-Si.
Spectral exclusivity is important within the scope of tandem cells because it allows
stacked active layer placement with minimal impact on individual layer performance. Although
10
11. the intensity of light attaining the second active layer may decrease due to top layer interference,
it still retains photons energetic enough to efficiently activate exciton formation in the donor
polymer. However, increased spectral overlap, such as that of PBTI3T and PTB7 in comparison
to PBTI3T and PSBTBT-Si (Figure 5), causes the first active layer to absorb a portion of the
wavelengths necessary for efficient performance of the second active layer. The addition of
PC70BM to the donor polymers in solution simulates the absorption of an active layer comprised
of both materials. It is important to note that in addition to the polymer peaks, PC70BM adds to
the absorption graphs of PBTI3T, PTB7, and PSBTBT-Si in the ~350-550 nm wavelength range,
emphasizing the difference of each donor polymer’s light absorption at higher wavelengths. In
this view, PSBTBT-Si:PC70BM in combination with PBTI-3T:PC70BM are logical choices for
tandem device active layers because of their large ~150 nm spectral difference. Moreover, this
material choice encompasses visible wavelengths and extends into near-IR. Although the
difference in absorption between PTB7:PC70BM and PBTI3T:PC70BM is much smaller (~50
nm), there is enough difference in the absorption of these active layers for PTB7: PC70BM to
provide complementary voltage gains in combination with the first active layer, especially given
each polymer’s strong single layer Voc and FF. In this scenario, however, the first active layer
dominates the second and skews results towards the performance of the dominating layer
(PBTI3T) supplemented by additional active layer (PTB7) characteristics.
11
12. Figure 6: Single layer cell performance of PBTI3T, PTB7, and PSBTBT-Si.
Polymer characteristics provide insight into device performance thanks to the Planck
relation E = hc/λ, which relates the wavelength of the light absorbed by active layer polymers to
the energy of their bandgap. As previously mentioned, donor polymer and acceptor polymer
bandgaps work within the device active layer to create voltage and, to some extent, current.
Performance of a solar cell is characterized by its J-V curve, a graphical representation of the
device’s current and voltage output in response to a regulated light source (Figure 4b). The
graph’s y-axis translates to current output (J), and the x-axis translates to voltage output (V).
Notable points on the J-V curve include the device’s short-circuit current (Jsc), which is the y-
intercept of the J-V graph, and is a representation of the cell’s maximum current under no
reverse voltage bias. Similarly, the device’s open-circuit voltage (Voc) is the x-intercept of the J-
V curve, and represents the cell’s maximum voltage output under full reverse bias. A final
notable characteristic of the J-V curve is the fill factor (FF), which is a measure of the curve’s
“squareness”, a representation of the power that the cell could produce under optimal load. Using
these three parameters, it is possible to determine the efficiency of a given solar cell by the
equation described in Figure 4b.
12
13. Single cell characterization was performed for each of the polymer active layers chosen
in this study; the results are shown above as J-V curves of devices representing the average
tested OPV employing each different donor polymer (Figure 6). The best efficiencies of
PSBTBT-Si, PTB7, and PBTI3T were 8.66%, 8.12%, and 4.33%, respectively (Table 2). This
project was unable to reproduce PSBTBT-Si’s best published single-cell PCE of 5.1% with
polymers sourced from 1-Materials Co.8,9
The decision to use PSBTBT-Si was based on its
optimal absorption spectrum rather than on its PCE. Although the Jsc of PSBTBT-Si is ~14.7
mA/cm2
, its inadequate fill factor (~48.8 %) and lower Voc (.604 V) bring down performance.
Ideally, its implementation in a tandem device structure would allow it to contribute a Voc close
to that of its single cell performance due to minimal spectral overlap with other materials.
This project’s medium-bandgap material, PTB7, has a published PCE of 7.4%.20
This
single-cell efficiency is the main reason for choosing PTB7 as a second active layer option,
especially given that this project’s optimization of PTB7 single cells pushed the polymer’s
efficiency to PCE = 8.12% (Table 2). Its lower HOMO energy level (Figure 1b) also leads to a
higher Voc, which helps to move its single-layer J-V curve closer to the optimal fill factor
(figure 6). PTB7’s high single-cell efficiency can be attributed to its especially high Jsc (16
mA/cm2
), good Voc (0.73 V) and decent FF of 69.4%. Previous tandem cells have made use of
PTB7 because of its high single layer performance, but, for lack of a better higher-bandgap
polymer choice, have paired it with a standard high-bandgap P3HT active layer.10
This project
sought to pair PTB7 with the novel high bandgap polymer PBTI3T to increase spectral mismatch
compared to previous tandem efforts with this medium-bandgap polymer, and thus provide more
distinctly additive characteristics. The performance of PBTI3T can be attributed to its
combination of high Voc (0.862 V), high FF (77.7%) and good Jsc (12.9%) (Table 2).
13
14. Figure 7: Optimization of PBTI3T polymer. Atomic force microscope study of blend films prepared under
differing conditions
(varying amounts of 1,8-diiodooctane). Table 1. Summary of polymer: PC70BM ratio and
DIO concentration.
The studied single layer devices employed bulk-heterojunction (BHJ) active layers,
which are a heterogeneous mixture of p-type polymer semiconductors as electron donors and n-
type semiconductors, mostly fullerene derivatives, as electron acceptors. The randomized
structure of the p/n junctions in BHJ OPVs provides interesting opportunities for device
morphology optimization. An example of morphology optimization on PBTI3T polymer is
illustrated in Figure 7. The resulting device performance is summarized in Table 1.
A challenge posed by the solution processing of multiple organic layers in succession is
the maintenance of layer uniformity and exclusivity throughout the tandem device. The use of
additives such as DIO provides control over the distribution of linear p-type polymers and
spherical n-type buckyball polymers within the active layer. The optimization of DIO
concentration to control domain size homogeneity to within the active layer solution is depicted
14
Polymer:
PC71BM
(w/w)
Solvent (v/v) Voc
(V)
Jsc
(mA/cm2
)
FF
(%)
PCE
(%)
1:1 CF 0.901 9.18 58.7 4.89
1:1.5 CF 0.877 8.14 60.3 4.30
1:2 CF 0.875 7.51 61.4 4.03
1:1 97%CF+3%DIO 0.869 12.4 70.0 7.54
1:1.5 97%CF+3%DIO 0.866 11.3 73.8 7.22
1:2 97%CF+3%DIO 0.863 9.59 75.4 6.24
1:1 95%CB+5%DIO 0.857 10.7 71.2 6.54
1:1.5 95%CB+5%DIO 0.861 10.2 76.5 6.74
1:2 95%CB+5%DIO 0.847 10.7 76.3 6.90
15. by AFM imaging (Figure 7). DIO provides selective solubility of PC70BM, allowing the
progressive increase in distribution of these molecules evenly amongst the film, thus reducing
the domain size of PC70BM and distance necessary for charges to travel before reaching
interface. Due to the exciton recombination length of ~10 nm, it is advantageous to distribute
both n and p-type polymers evenly for efficient charge separation along well-spaced p/n
interfaces. This corresponds to a generally enhanced device FF. Moreover, the highest current
(lowest charge recombination) in the DIO optimized PBTI3T occurs with an even (1:1)
PBTI3T:PC70BM ratio and 3% DIO concentration (Table 1). 6
To some extent, it is possible to control layer morphology by employing thin (~5 Ǻ)
layers of vacuum deposited silver. This method provides a physical barrier to reduce film surface
roughness, and especially reduce miscibility between successive solution deposited layers. This
project’s tandem devices employed these silver interlayers between both active layers, reflected
by data as a small but statistically insignificant improvement in Jsc and PCE. To determine
whether this method is valuable to OPV structure theory, more testing must be done. This type of
interlayer aims to improve charge carrier transport between active layers.
Ideally, a device interfacial layer (IFL) should have low electrical resistance, high optical
transparency in the visible and infrared range, low potential energy barriers for both electron and
hole extractions, easy-fabrication process, and protection for the prior-deposited active layer in
solution-processed tandem OPVs.13,14
Zinc oxide, an established n-type transparent conducting oxide (TCO) in OPV literature,
was used multiple times within these tandem devices (Figure 2) for selective charge transport at
device cathodes.13
Once charges are separated and have traveled to the device’s cathode, it is
15
16. possible to analyze cell performance. ZnO exhibits many of the optimal interlayer characteristics
mentioned previously, notably forming a tough near-crystalline film once annealed.
Additionally, poly(ethylene-dioxythiophene) doped with polystyrene-sulfonic acid
(PEDOT:PSS) is a p-type material that, and facilitates hole (h+
) transport between active layers.7
PEDOT:PSS is a non-ideal IFL in the sense that it is not highly transparent, and provides
minimal protection of lower layers as it remains amorphous once annealed.
However, two different types of PEDOT:PSS were used in the device fabrication. One
was only the PEDOT:PSS solution purchased from an outside source with TritonTM
X-100
surfactant added for wettability and discrete layer deposition. The other was the same
PEDOT:PSS/Triton solution, but modified according to Yang et al.14
to improve conductivity.
The production process itself is an important component of OPV production, as it
determines (to some extent) how well the devices will conduct current. There are fewer layers to
process in single cells, avoiding damage to other layers. In tandems, the production process
involves at least twice as many steps, all of which affect the preceding layers. This causes the
interlayers to be less uniform than is preferable, allowing charges to bleed through and diffuse to
unwanted layers or recombine, decreasing the Jsc and PCE of the cell. If the solution processing
and spin coating is done imperfectly, the surface of the cell becomes even less uniform and more
rough, with each layer added aggravating the problem. An additional issue with solution
deposited active layers is the possibility of sub-layer dilution by the solvent of the second active
layer, which would have generally detrimental effects to cell performance. Finally, roughness
decreases the ohmic contact and efficiency of electrodes because neither silver nor MoO3 can
cover edges of surface imperfections that have angles >90 degrees. -
Results
16
17. Table 2. Summary of single-layered and tandem device performance.
Device Solvent Thickness (nm) Voc (V) Jsc (mA/cm2
) FF (%) PCE (%)
PBTI3T CF 140 0.862 12.9 77.7 8.66
PTB7 CB 90 0.730 16.0 69.4 8.12
PSBTBT-Si CB 100 0.604 14.7 48.8 4.33
PBTI3T CF 60 0.880 7.89 74.8 5.20
PTB7 CB 60 0.739 12.9 70.3 6.71
PSBTBT-Si CB 70 0.600 8.38 50.3 2.53
PTB7+PBTI3T CB+CF 60 + 140 1.20 8.21 65.9 6.49
PBTI3T+PSBTBT-Si CB+CF 60 + 70 1.41 4.85 48.0 3.28
In order to produce the best possible tandem cells, this research investigated multiple
pathways (polymer bandgap and spectral engineering, single layer device optimization,
morphology control, interfacial layer design) for the optimization of Voc, Jsc, and FF in search of
maximum tandem PCE. The best tandem cells recorded had a PCE of 6.49%, a VOC of 1.2 V, and
a JSC of 8.21 mA/cm2 (Table 2, Figure 8). The two materials used in tandem to produce these
results, PBTI3T and PTB7, demonstrated high efficiency and JSC in single cells, and are shown
here to perform very well in tandem (Table 2, Figure 7). These findings show the successful
17
Figure 8. J-V curve of single-layer performances of
PBTI3T and PTB7, with tandem performance of
the combined polymers.
Figure 9. J-V curve of single-layered cell
performances of PBTI3T and PSBTBT-Si,
with tandem performance of the combined.
18. partial Voc addition of the respective polymers’ single layer performance, which combine with
adequate FF retention to balance the unfortunate decrease in Jsc, perhaps due to inadequate IFL
treatment or poor device structure.
The major achievement of such a tandem pairing is the resulting voltage of the device,
which is the additive combination of each respective active layer’s Voc. Although the
PBTI3T/PSBTBT-Si tandem cells did not render as high PCE devices as PBTI3T/PTB7 cells, the
resulting voltages of PBTI3T/PSBTBT-Si devices were completely additive (VPBTI3T + VPSBTBT-Si =
VPBTI3T+PSBTBT-Si) (Table 2). Unfortunately, the increased voltage was unable to overcome the
initial handicap of low FF and PCE of PSBTB-Si, which is reflected by the large curve of the
tandem J-V graph (Figure 9). The superiority of PTB7 and PBTI3T over PSBTBT-Si is
demonstrated in the tandem cell efficiency results and graphical comparison of the respective
tandem cell graphs (Figure 8,9). This is a reflection of multiple factors -- the PTB7 and the
PBTI3T both have vastly superior single cell J-V curves in comparison to PSBTBT-Si (figure 6).
The shapes of the PBTI3T and the PTB7 single-cell J-V curves show that they work well in
tandem; the PBTI3T has a higher voltage than the PTB7, and the PTB7 has a higher current than
the PBTI3T (a result of its lower bandgap) (Table 2). The combination of these two polymers,
which are either slightly Jsc or Voc deficient, creates a solar cell that has an incremental increase
of both, making the new J-V curve move closer to a better FF (square graph) (Figure 8).
Conclusions & Future Work
In this study, the exploration of high-performance single cell polymers has been extended
to tandem cells, advancing the usefulness and applicability of OPVs in solar energy technology.
These cells not only improve upon existing organic tandem technology through increased Voc,
but also leave room for optimization and perfection of devices using this project’s two most
18
19. successful polymers in tandem, PBTI3T and PTB7. Although the goal of record breaking device
PCEs was not attained, the unsatisfactory overall results obtained from PBTI3T/PSBTBT-Si
cells shroud the fact that distinctly additive voltages were observed in these devices. This largely
increased Voc is a characteristic unique to tandem devices, and provides a very high theoretical
PCE limit despite the lack of tandem Jsc and FF optimization. Overall, this project achieved
results that came close to matching published single cell results, and, with a novel high bandgap
active layer (PBTI3T) that has previously never been paired in tandem cells, achieved results that
are consistent with the current literature on tandem OPVs.
These results validate the methods and techniques adopted in this project, despite the fact
that the ideal processing conditions for single cells were not attainable for tandem cell production
during the project. In particular, the tandem cell processing conditions did not allow for
preventing surface roughness and layer mixing, thus decreasing the cell’s Jsc and FF. Specific
areas for improvement would further optimization of single-layer cells to improve individual
polymer performance, more precise tandem device fabrication, and the use of increasingly
advanced interfacial materials as they become available. Building on the successful additive
voltages of the PBTI3T/PTB7 and PBTI3T/PSBTBT-Si tandem cells and refining production
processes to match single cells’ Jsc and FF levels, tandem cells have the potential to attain or
exceed 15% PCE. This research provides necessary data on tandem device optimization, as well
as promising results for the implementation of previously untested polymer combinations,
including a new high efficiency polymer PBTI3T. Added to the versatility and ease of
installation that characterizes organic photovoltaics, these results light the way for eventual
breakthroughs in organic solar technology.
19