Uploaded bybisquertGroup
8,061 views

Impedance Spectroscopy

1. The document discusses advances in impedance spectroscopy for analyzing solar energy conversion devices like dye-sensitized solar cells. 2. Impedance spectroscopy allows measurement of resistances and capacitances in solar cells, which provides insight into recombination, diffusion lengths, and energetics. 3. Parameters like the chemical capacitance, recombination resistance, and diffusion coefficient can be extracted and related to performance factors like open-circuit voltage, short-circuit current, and fill factor.

Embed presentation

Advances in impedance spectroscopy of solar energy conversion devices Juan Bisquert Photovoltaic and Optoelectronic Devices Group Universitat Jaume I 12071 Castelló Spain 27 10 2012
Solar cell concepts
Photovoltaics: Light absorber
Photovoltaics: Charge separation Bisquert, J.; Cahen, D.; Rühle, S.; Hodes, G.; Zaban, A. "Physical chemical principles of photovoltaic conversion with nanoparticulate, mesoporous dye-sensitized solar cells." The Journal of Physical Chemistry B, 108, 8106, 2004.
Fundamental model for a solar cell Infinite mobilities- no transport resistance Fermi level straight inside Perfect selective contacts 1. Generation 2. Recombination Fermi level fixed inside by 3. Extraction external potential, independent of illumination Bisquert, J.; Cahen, D.; Rühle, S.; Hodes, G.; Zaban, A. "Physical chemical principles of photovoltaic conversion with nanoparticulate, mesoporous dye-sensitized solar cells." The Journal of Physical Chemistry B, 108, 8106, 2004.
The diode equation for a solar cell Dark At V = 0 equilibrium of generation and recombination jr (0) = j0 Rise of the Fermi level enhances recombination jr (V ) = j0 e qV / mk BT Sunlight Equilibrium of generation and recombination j = jsc + j0 − j0 e qV / mk BT Can be measured directly by Also can be expressed in terms of carrier density recombination resistance
Current voltage curves
Solar cell concepts
Dye Solar Cells
Dye-sensitized solar cell Nayak, Kahn, Garcia.Belmonte, Bisquert, Cahen, Energy and Environmental Science 2012
Limitation to efficiency The DSC It is a 3 –materials solar cell There is a price of energy differences, but more versatile and potentially cheap
Influence of energetics: higher Voc If the conduction band of TiO2 is higher, the Fermi level can rise higher (in principle) and photovoltage may become larger
Influence of energetics: photocurrent If the conduction band of TiO2 is higher, there is less injection from the dye molecules, and current decreases
The redox potential of the hole conductor New redox couples? The Fermi level of the hole conductor is lower than I-/I3- liquid electrolyte, which gives higher photovoltage
The energy diagram
Diffusion-recombination transmission line model J. Bisquert, J. Phys. Chem. B 106, 325-333 (2002) F. Fabregat-Santiago, J. Bisquert, G. Garcia-Belmonte, G. Boschloo, A. Hagfeldt Solar En. Mat. Sol.Cells, 87, 117-131 (2005).
Measurement of resistances and capacitances by Impedance Spectroscopy
DSC device IS model J. Bisquert, J. Phys. Chem. B 106, 325-333 (2002) F. Fabregat-Santiago, J. Bisquert, G. Garcia-Belmonte, G. Boschloo, A. Hagfeldt Solar En. Mat. Sol.Cells, 87, 117-131 (2005).
How do we determine energetics? The chemical capacitance measures the density of states in the bandgap (DOS) and this provides a reference of the Ec in different cells. Pt TCO re d o x e le c t r o ly t e T iO 2 E C E Fn e le c tr ic p o te n tia l e le c tr o n e n e r g y eV E F0 E re d o x
Chemical capacitance The conduction band of TiO2 is situated at a given level with respect to the Fermi level of hole conductor. The chemical capacitance measures the density of states in the bandgap (DOS) and this provides a reference of the Ec in different cells. TC O re d o x Pt Chemical capacitance e le c t r o ly t e T iO 2 E C ∂n E Fn Cµ = q 2 e le c t r ic p o t e n t ia l e le c t r o n e n e r g y eV ∂E Fn E F0 E re d o x Bisquert, J. "Chemical capacitance of nanostructured semiconductors: its origin and significance for heterogeneous solar cells". Phys. Chem. Chem. Phys. 2003, 5, 5360
Interpretation of recombination resistance '  q VF  Rrec = R0 exp − β  k BT   The model considers a distribution of surface states, and charge transfer via Marcus model 1 T β= + α s = 0. 5 + 2 T0 s Q. Wang, M. Grätzel, F. Fabregat-Santiago, J. Bisquert et al., J. Phys. Chem. B. 110, 25210-25221 (2006) J. Bisquert, F. Fabregat –Santiago, I. Mora-Seró, G. Garcia-Belmonte, S. Giménez, J. Phys. Chem. C, 113, 17278 (2009).
Fill factors The recombination order β relates directly to the diode ideality factor m = 1.5-2.5 j = jsc + j0 − j0e qβV / k BT Restrictions on the fill factor
Shif of the band changes the diode factor Jennings and Wang show that the diode factor changes when the conduction band is brought down by the addition of lithium. m = 1 at high lithium content (low cb position) Because electron transfer is from conduction band and linear recombination occurs J. Jennings, Q. Wang J. Phys. Chem. C, 114, 1715 (2010).
The diffusion length The diffusion coefficient is related only to resistances Rrec Ln = Dnτ n = L Rtr J. Bisquert, J. Phys. Chem. B, 106, 325-333 (2002)
Variations of the diffusion length The diffusion length increases with the bias This is indicating that the free electron lifetime is not a Ln = Dnτ n = D0τ f constant Quantitative description is made by Peter et al. Using nonlinear recombination model J. Villanueva-Cab, H. Wang, G. OskamL. M. Peter, J. Phys. Chem. Lett. 1, 748, (2010).
Phtalocyanine dyes O O O O O O O O N N N N N N H N Zn N N N H N N N N N N O O O O O O O O O O ZnPc-1 H2Pc-2 Barea, E. M.; Ortiz, J.; Payá, F. J.; Fernández-Lázaro, F.; Fabregat-Santiago, F.; Sastre-Santos, A.; Bisquert, J. "Energetic factors governing injection, regeneration and recombination in dye solar cells with phthalocyanine sensitizers". Energy and Environmental Science 2010, 3, 1985
Phtalocyanine dyes n at VOC EC EC - EFn Voc jsc η Sample FF (cm-3) (eV) (eV) (V) (mA/cm2) (%) ZnPc-1 0.44 3.48 0.66 1.01 4.2 x 1017 -4.00 0.31 H2Pc-2 0.35 5.71 0.57 1.14 1.5 x 1018 -4.13 0.27 N719 0.45 10.90 0.51 2.50 3.0 x 1018 -4.11 0.19 Barea, E. M.; Ortiz, J.; Payá, F. J.; Fernández-Lázaro, F.; Fabregat-Santiago, F.; Sastre-Santos, A.; Bisquert, J. "Energetic factors governing injection, regeneration and recombination in dye solar cells with phthalocyanine sensitizers". Energy and Environmental Science 2010, 3, 1985
Phtalocyanine dyes The band is shifted for ZnPC We move the potential scale to compare recombination ZnPc has more recombination Recombination in H2Pc is the same as in N719
Phtalocianyne dyes Recombination in H2Pc is the same as in N719 With the same current it would give the same voltage Barea, E. M.; Ortiz, J.; Payá, F. J.; Fernández-Lázaro, F.; Fabregat-Santiago, F.; Sastre-Santos, A.; Bisquert, J. "Energetic factors governing injection, regeneration and recombination in dye solar cells with phthalocyanine sensitizers". Energy and Environmental Science 2010, 3, 1985
The DOS an essential reference to explain performance Explanation of the low VOC. 1)an inefficient injection 2)the low position of the conduction band of TiO2,
Identifying the role that the dye structure plays in DSC performance why YD2 porphyrin dye Acceptor• Can achieve such a high performance group close to that of a Ru commercial dye? Donor group Besides of the dye structure and the related photophysical properties. bridge •What other key parameters in a DSC influence YD2 strongly the overall power conversion efficiency? Diau, C.-Y. Yeh, J. Mater. Chem. 2010, 20, 1127 Angew. Chem. Int. Ed. 2010, 49, 6646 –6649
YD2 YD0 Sample name YD2 YD0 N719 Current density (mA·cm ) N719 Voc (V) -2 15 0.66 0.65 0.74 jsc (mA/cm2) 15.4 6.92 12.6 10 FF 0.62 0.73 0.70 Efficiencysame condictions 7% efficiency is the record * Under (%)* 6.36 3.29 6.54 5 0 0.0 0.2 0.4 0.6 0.8 Potential (V) N719 Barea, E. M.; Gonzalez-Pedro, V.; Ripolles-Sanchis, T.; Wu, H.-P.; Li, L.-L.; Yeh, C.-Y.; Diau, E. W.-G.; Bisquert, J. "Porphyrin Dyes with High Injection and Low Recombination for Highly Efficient Mesoscopic Dye-Sensitized Solar Cells". The Journal of Physical Chemistry C 2011, 115, 10898
J. Phys. Chem. B 2006, 110, 25210-25221 10-2 105 (a) (b) -2 Capacitance / F·cm 104 2 Rrec / Ohms·cm 10-3 103 102 10-4 101 10-5 100 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Applied Potential / V Applied Potential / V
N719 Sample name YD2 YD0 N719 Voc (V) 0.66 0.65 0.74 jsc (mA/cm2) 15.4 6.92 12.6 FF 0.62 0.73 0.70 Efficiency (%) 6.36 3.29 6.54
Sample name YD2 YD0 N719 Voc (V) 0.66 0.65 0.74 jsc (mA/cm2) 15.4 6.92 12.6 FF 0.62 0.73 0.70 Efficiency (%) 6.36 3.29 6.54 β 0.47 0.73 0.70 j0 (mA/cm2) 7.75e-05 6.09e-08 2.09e-08 j0k (mA/cm ) 2 54 1406 213 α 0.29 0.30 0.24 ∆Ec vs ref (mV) -123 -32.0 Ref Rseries (ohm) 19.5 19.4 17.9 Internal FF 0.73 0.81 0.81 Internal efficiency (%) 7.41 3.58 7.54 Barea, E. M.; Gonzalez-Pedro, V.; Ripolles-Sanchis, T.; Wu, H.-P.; Li, L.-L.; Yeh, C.-Y.; Diau, E. W.-G.; Bisquert, J. "Porphyrin Dyes with High Injection and Low Recombination for Highly Efficient Mesoscopic Dye-Sensitized Solar Cells". The Journal of Physical Chemistry C 2011, 115, 10898
• ISTPro Features - Analyzes IS data of dye-sensitized solar cells (DSC). - Allows to treat impedance spectroscopy parameters to obtain the essential parameters of the DSC performance. - Display the
• ISTPro Features Main Window:
• ISTPro Features
Organic solar cells
Organic solar cells Sunflower project: http://sunflower-fp7.eu
Organic solar cell On Voltage, Photovoltage, and Photocurrent in Bulk Heterojunction Organic Solar Cells Juan Bisquert and Germa Garcia-Belmonte, J. Phys. Chem. Lett. 2011, 2, 1950–1964
Organic solar cell Ratcliff, E. L.; Zacher, B.; Armstrong, N. R. "Selective Interlayers and Contacts in Organic Photovoltaic Cells". The Journal of Physical Chemistry Letters 2011, 2, 1337.
The bands and the Fermi levels Dielectric (depletion) capacitance The chemical capacitance
Band bending and Fermi levels Donor LUMO Acceptor LUMO EF Donor HOMO --- -- -- Cathode Acceptor HOMO w V=0
Band bending and Fermi levels Donor LUMO Acceptor LUMO EF Donor HOMO -- -- Cathode Acceptor HOMO w V < Vfb
Band bending and Fermi levels Donor LUMO Acceptor LUMO EF Donor HOMO --- Cathode Cathode Acceptor HOMO w V < Vfb
Band bending and Fermi levels Donor LUMO Acceptor LUMO EF Donor HOMO - Cathode Acceptor HOMO w V < Vfb
Band bending and Fermi levels Donor LUMO Acceptor LUMO EF Donor HOMO Cathode Acceptor HOMO V = Vfb
Depletion region – Mott Schottky plots Increase in the capacitance caused by the reduction of the depletion zone Characterization of nanostructured hybrid and organic solar cells by impedance spectroscopyw Francisco Fabregat-Santiago, Germa Garcia-Belmonte, Ivan Mora-Sero´ and Juan Bisquert Phys. Chem. Chem. Phys., 2011, 13, 9083–9118
Depletion region -P. P. Boix, G. Garcia-Belmonte, U. Muñecas, M.Neophytou, C. Waldauf, R. Pacios, Appl Phys. Lett 95, 1, (2009)
Depletion region
Additional proofs of electrical field confined near the cathode FIG. 2. (Color online) (a) The mean-field potential line-profile of the cross-sectional image and (b) the corresponding energy band diagram after contacting of all layers. Appl. Phys. Lett. 99, 243301 (2011) © 2011 American Institute of Physics
Measured DOS of organic BHJ Measurement of the DOS The chemical capacitance ∂nL Cµ ( E ) = q 2 = qg n ( E Fn ) ∂EFn PCBM-P3HT solar cell Germà Garcia-Belmonte, Pablo P. Boix, Juan Bisquert, Michele Sessolo, and Henk J. Bolink Solar Energy Materials and Solar Cells, 94, 366 (2010)
Comparison of different fullerenes with similar reduction potential but different DOS DPM6 PCBM Higher Voc related to full occupancy of intermediate electronic band G. Gar Germa Garcia-Belmonte Pablo P. Boix, Juan Bisquert, Martijn Lenes, Henk J. Bolink, Andrea La Rosa, Salvatore Filippone,and Nazario Martín§,J. Phys. Chem. Lett. 1 (2010) 2566-2571
Carrier diffusion in organic BHJ PCBM-P3HT solar cell Diffusion-Recombination Determines Collected Current and Voltage in Polymer:Fullerene Solar Cells Teresa Ripolles-Sanchis, Antonio Guerrero, Juan Bisquert, and Germà Garcia-Belmonte, J. Phys. Chem. C 2012, 116, 16925−16933
The Fermi level in the Gaussian distribution In the presence of a Gaussian distribution, the carriers do not lie below the Fermi level. Bisquert, J. "Interpretation of electron diffusion coefficient in organic and inorganic semiconductors with broad distributions of states". Physical Chemistry Chemical Physics 2008, 10, 3175
Why is Voc less than HOMO-LUMO difference? This is explained by disorder qVoc = E Fn − E Fp σ n2 + σ p2  Nn N p  qVoc = E g − − k BT ln  np   2k BT   This formula derived by G. Garcia-Belmonte quantifies the energy loss related to disorder Garcia-Belmonte, G. "Temperature dependence of open-circuit voltage inorganic solar cells from generation–recombination kinetic balance". Solar Energy Materials and Solar Cells 2010, 94, 2166
Recombination in organic BHJ
Energetics of recombination Guerrero, A.; Marchesi, L. F.; Boix, P. P.; Bisquert, J.; Garcia-Belmonte, G. "Recombination in Organic Bulk Heterojunction Solar Cells: Small Dependence of Interfacial Charge Transfer Kinetics on Fullerene Affinity". The Journal of Physical Chemistry Letters 2012, 3, 1386
Reconstruction of current voltage curves from recombination resistance data Boix, P. P.; Guerrero, A.; Marchesi, L. F.; Garcia-Belmonte, G.; Bisquert, J. "Current-Voltage Characteristics of Bulk Heterojunction Organic Solar Cells: Connection Between Light and Dark Curves". Advanced Energy Materials 2011, 1, 1073
Reconstruction of current voltage curves from recombination resistance data −1 k BT  dj  jsc = j rec (Voc ) = L Rrec = L rec   dV  βqRrec (Voc )  F  Boix, P. P.; Guerrero, A.; Marchesi, L. F.; Garcia-Belmonte, G.; Bisquert, J. "Current-Voltage Characteristics of Bulk Heterojunction Organic Solar Cells: Connection Between Light and Dark Curves". Advanced Energy Materials 2011, 1, 1073
Quantum dot solar cells
Charge Transfer, Transport and Recombination Processes T1→ e- transport R4 T2→ h+ transport I1→ e- injection from QD CB I2→ e- injection from QD trap I1 R5 I3→ e- back injection to QD T1 I2 I4 → h+ injection from QD CB Tr3 I3 Tr1 R1 I5 → h+ injection from QD trap Tr1→ e- trapping in the QD R2 T2 R3 Tr2 → h+ trapping in the QD I4 R1→ e-- h+ band-to-band Tr2 I5 recombination in the QD R2→ e-- h+ trap mediated recombination in the QD Electron QD Hole R3→ recombination of e- in the Transporter Transporter TiO2 with h+ in the QD R4→ recombination of e- in the TiO2 with h+ in the HT R5→ recombination of e- in the QD with h+ in the HT - G. Hodes, J. Phys. Chem. C 2008, 112, 17778–17787
Quantum dot solar cells Boix, P. P.; Larramona, G.; Jacob, A.; Delatouche, B.; Mora-Seró, I.; Bisquert, J., Hole Transport and Recombination in All-Solid Sb2S3-Sensitized TiO2 Solar Cells Using CuSCN As Hole Transporter. Journal of Physical Chemistry C 2012, 116, 1579–1587..
Sensitizer Material PbS/CdS CdS PbS Combination of different kinds of QDS increases dramatically cell performance. Braga et al., J. Phys. Chem. Lett. 2011, 2, 454–460
Surface treatment Effect Surface treatments have a dramatic effect on solar cell performance Barea et al. J. AM. CHEM. SOC. 2010, 132, 6834–6839
Water splitting with sunlight
Water splitting cell Energy diagram of a PEC cell for the photo-electrolysis of water. The cell is based on an n-type semiconducting photo-anode. Gerischer, H. "The impact of semiconductors on the concepts of electrochemistry". Electrochimica Acta 1990, 35, 1677-1699
Semiconductor photoelectrochemistry Reichman Appl. Phys. Lett. 1980, 36, 574
Hematite GrätZel et al J. AM. CHEM. SOC. VOL. 132, 2010
Photogeneration of electrons and holes Charge transfer via surface states Carrier density and interfacial kinetics in mesoporous TiO 2 during water splitting determined by impedance spectroscopy Sixto Giménez, J. Electroanal Chem 2012
Water splitting cell Simple model of a photoelectrochemical cell Bertoluzzi, L.; Bisquert, J. "Equivalent Circuit of Electrons and Holes in Thin Semiconductor Films for Photoelectrochemical Water Splitting Applications". The Journal of Physical Chemistry Letters 2012, 3, 2517
Equivalent circuit Simple model of a photoelectrochemical cell Bertoluzzi, L.; Bisquert, J. "Equivalent Circuit of Electrons and Holes in Thin Semiconductor Films for Photoelectrochemical Water Splitting Applications". The Journal of Physical Chemistry Letters 2012, 3, 2517
Thin hematite layer JV curve and impedance model Klahr, B.; Gimenez, S.; Fabregat-Santiago, F.; Hamann, T.; Bisquert, J. "Water Oxidation at Hematite Photoelectrodes: The Role of Surface States". Journal of the American Chemical Society 2012, 134, 4294
impedance results Klahr, B.; Gimenez, S.; Fabregat-Santiago, F.; Hamann, T.; Bisquert, J. "Water Oxidation at Hematite Photoelectrodes: The Role of Surface States". Journal of the American Chemical Society 2012, 134, 4294
Impedance model and results Klahr, B.; Gimenez, S.; Fabregat-Santiago, F.; Hamann, T.; Bisquert, J. "Water Oxidation at Hematite Photoelectrodes: The Role of Surface States". Journal of the American Chemical Society 2012, 134, 4294
Other redox couple water Fe(CN)6]3-/4- With [Fe(CN)6]3-/4- in solution, however, the charge transfer resistance is essentially constant over the measured potential range for a given light intensity as shown in figure 4c. The absence of a measureable surface state capacitance and absence of a dip in the charge transfer resistance suggests that photooxidaiton of [Fe(CN)6]4- does not involve surface states and can be described as a simple outersphere Klahr, B.; Gimenez, S.; Fabregat-Santiago, F.; Bisquert, J.; Hamann, T. W. "Electrochemical and photoelectrochemical investigation of water oxidation with hematite electrodes". Energy & Environmental Science 2012, 5, 7626
Surface treatment with Co-Pi Sivula et al., Energy Environ. Sci. 2011, 4, 1759 Durrant, Gratzel, et al JACS 2011
Interpretation of Co-Pi Klahr, B.; Gimenez, S.; Fabregat-Santiago, F.; Bisquert, J.; Hamann, T. W. "Photoelectrochemical and Impedance Spectroscopic Investigation of Water Oxidation with Co-Pi -Coated Hematite Electrodes". Journal of the American Chemical Society 2012, 134, 16693
Thank you
Impedance Spectroscopy

More Related Content

PDF
Mie theory of light scattering
byGandhimathi Muthuselvam
 
PPT
Models for organic solar cell and impedance spectroscopy results
bybisquertGroup
 
PPT
Xps
bycynon
 
PPTX
XRF (X-ray fluorescence) By Hossein bandori
byHamed Pakdaman
 
PPT
Basics of Electrochemical Impedance Spectroscopy
byGamryInstruments
 
PPT
Introduction organic electronics
byyanheyanhe
 
PPTX
Plasmonic1 new
byBesa Hoxha
 
PPT
Nonlinear Optical Materials
bykrishslide
 
Mie theory of light scattering
byGandhimathi Muthuselvam
 
Models for organic solar cell and impedance spectroscopy results
bybisquertGroup
 
Xps
bycynon
 
XRF (X-ray fluorescence) By Hossein bandori
byHamed Pakdaman
 
Basics of Electrochemical Impedance Spectroscopy
byGamryInstruments
 
Introduction organic electronics
byyanheyanhe
 
Plasmonic1 new
byBesa Hoxha
 
Nonlinear Optical Materials
bykrishslide
 

What's hot

PDF
Misconceptions in Photocatalysis
byHariprasad Narayanan
 
PPTX
Xrd
byBirla institute of technology
 
PDF
X ray Photoelectron Spectroscopy (XPS)
byNano Encryption
 
PPT
2018 HM PIXE PARTICLE -INDUCED X-RAY EMISSION AN ANALYTICAL TECHNIQUE
byHarsh Mohan
 
PPTX
Pawan Homogeneous catalyst for CO2 reduction
byPawan Kumar
 
PPTX
Organic electronics
byPrince Joshy
 
PDF
SOFC perovskite- DFT work
byShruba Gangopadhyay Ph.D.
 
PDF
Xps (x ray photoelectron spectroscopy)
byZaahir Salam
 
PPTX
Xrf
byTejasvi Bhatia
 
PPTX
Spintronics ppt
byAbhishek Shringi
 
PPT
Developments in organic solar cells
byAkinola Oyedele
 
PPTX
ELECTROCHEMICAL SENSORS
byLavaraj Devkota
 
PPT
Solution combustion method for syntheis of nano particles
byGanapathirao Kandregula
 
PPTX
Sputtering process and its types
byMuhammadWajid37
 
PPTX
electrochemical impedence spectroscopy
byAmol Srivastava
 
PPTX
Thesis Presentation
byKetan Solanki
 
PDF
Theory of surface plasmon polaritons
byGandhimathi Muthuselvam
 
PPTX
degradation of pollution and photocatalysis
byPraveen Vaidya
 
PPTX
New Material:Perovskites presentation
byJohn Shiloba Pishikeni
 
PPTX
mahfooz_ supercapacitor
byMahfooz Alam
 
Misconceptions in Photocatalysis
byHariprasad Narayanan
 
Xrd
byBirla institute of technology
 
X ray Photoelectron Spectroscopy (XPS)
byNano Encryption
 
2018 HM PIXE PARTICLE -INDUCED X-RAY EMISSION AN ANALYTICAL TECHNIQUE
byHarsh Mohan
 
Pawan Homogeneous catalyst for CO2 reduction
byPawan Kumar
 
Organic electronics
byPrince Joshy
 
SOFC perovskite- DFT work
byShruba Gangopadhyay Ph.D.
 
Xps (x ray photoelectron spectroscopy)
byZaahir Salam
 
Xrf
byTejasvi Bhatia
 
Spintronics ppt
byAbhishek Shringi
 
Developments in organic solar cells
byAkinola Oyedele
 
ELECTROCHEMICAL SENSORS
byLavaraj Devkota
 
Solution combustion method for syntheis of nano particles
byGanapathirao Kandregula
 
Sputtering process and its types
byMuhammadWajid37
 
electrochemical impedence spectroscopy
byAmol Srivastava
 
Thesis Presentation
byKetan Solanki
 
Theory of surface plasmon polaritons
byGandhimathi Muthuselvam
 
degradation of pollution and photocatalysis
byPraveen Vaidya
 
New Material:Perovskites presentation
byJohn Shiloba Pishikeni
 
mahfooz_ supercapacitor
byMahfooz Alam
 

Similar to Impedance Spectroscopy

PDF
Pin mặt trời chất màu nhạy quang www.mientayvn.com
bywww. mientayvn.com
 
PPT
The Science Behind Dye-Sensitized Solar Cells
byswissnex San Francisco
 
PDF
Enhancement in the efficiency of solar cells final ppt
bySwapnil Agarwal
 
PPTX
Dssc (Dye sensitized solar cell)
byPreeti Choudhary
 
PDF
Jim Sites | CSU
byGW Solar Institute
 
PDF
The_Status_and_Outlook_for_the_Photovoltaics_Industry_2007 BP
byDmitry Tseitlin
 
PDF
MANUFACTURE OF ORGANIC PHOTOVOLTAICS
bySuat Furkan ISIK
 
PPTX
Chemistry and physics of dssc ppt
byN.MANI KANDAN
 
PPTX
Materials for the Optimization of Solar Energy Harvesting.
bySociedade Brasileira de Pesquisa em Materiais
 
PPT
Photosyntheis in a test tube-Dye sensitized solar cells (USPseminar)
byAtul Raturi
 
PDF
I ls in_dssc
byMukund Ghavre
 
PDF
D09.06.06.presentation
byRelhy project
 
PPTX
The Versatility of Mesoscopic Solar Cells.
bySociedade Brasileira de Pesquisa em Materiais
 
PDF
Efficiency enhancement of photovoltaic performance
byAlexander Decker
 
PDF
Introduction to Photoelectrochemical (PEC) Water Splitting
byAnamika Banerjee
 
PDF
Application Note: Simple Method of Measuring the Band Gap Energy Value of TiO...
byPerkinElmer, Inc.
 
PDF
University of Toronto Chemistry Librarians Workshop June 2012
byBrock University
 
PDF
Iaetsd dye sensitized solar cell
byIaetsd Iaetsd
 
PDF
Aem Lect9
bylangtudaikieu
 
PPTX
9 IV and IPCE measurements blah blah blah
byrobperezzz452
 
Pin mặt trời chất màu nhạy quang www.mientayvn.com
bywww. mientayvn.com
 
The Science Behind Dye-Sensitized Solar Cells
byswissnex San Francisco
 
Enhancement in the efficiency of solar cells final ppt
bySwapnil Agarwal
 
Dssc (Dye sensitized solar cell)
byPreeti Choudhary
 
Jim Sites | CSU
byGW Solar Institute
 
The_Status_and_Outlook_for_the_Photovoltaics_Industry_2007 BP
byDmitry Tseitlin
 
MANUFACTURE OF ORGANIC PHOTOVOLTAICS
bySuat Furkan ISIK
 
Chemistry and physics of dssc ppt
byN.MANI KANDAN
 
Materials for the Optimization of Solar Energy Harvesting.
bySociedade Brasileira de Pesquisa em Materiais
 
Photosyntheis in a test tube-Dye sensitized solar cells (USPseminar)
byAtul Raturi
 
I ls in_dssc
byMukund Ghavre
 
D09.06.06.presentation
byRelhy project
 
The Versatility of Mesoscopic Solar Cells.
bySociedade Brasileira de Pesquisa em Materiais
 
Efficiency enhancement of photovoltaic performance
byAlexander Decker
 
Introduction to Photoelectrochemical (PEC) Water Splitting
byAnamika Banerjee
 
Application Note: Simple Method of Measuring the Band Gap Energy Value of TiO...
byPerkinElmer, Inc.
 
University of Toronto Chemistry Librarians Workshop June 2012
byBrock University
 
Iaetsd dye sensitized solar cell
byIaetsd Iaetsd
 
Aem Lect9
bylangtudaikieu
 
9 IV and IPCE measurements blah blah blah
byrobperezzz452
 

Recently uploaded

PDF
The Emergence of Empathic XR: AWE Asia 2026 keynote
byMark Billinghurst
 
PDF
AI for Risk Management & Fraud Detection ppt.pdf
byalexmartincaneda
 
PDF
UiPath Automation Developer Associate Training Series 2026 - Session 1
byDianaGray10
 
PPTX
apidays Paris 2025 | Integration is Feminist: Building Peace in Distributed S...
byapidays
 
PDF
Mesh WiFi Router: The Smart Solution for Fast, Seamless, Whole-Home Internet
byAeroMesh Systems
 
PDF
Startup Formation Collapses While Acquisition Activity Hits New High!
byMemoori
 
PDF
TravelTech Paris 2025 | The EU Digital Identity Wallet and it’s impact on Tra...
byapidays
 
PDF
The Manifesto for AI-enabled Governance !
byYannis Charalabidis
 
PDF
Self-Correction Failure Diagnostic: Detecting Drift in Complex Systems
bySystems Research Group
 
PPTX
Introduction to Artificial Intelligence (AI).pptx
byammar414783
 
PDF
Designing a Blog Using Wordpress
bymarkzubi50
 
PPTX
Computer architecture, Computer architecture ,Computer architecture
bywaheedqazi123
 
PDF
GenerationAI Paris 2025 | City of Light (COL)
byapidays
 
PPTX
How Does an ICO Launchpad Work Step-by-Step Breakdown.pptx
byTom Hardy S
 
PPTX
Automation Without Apprentices: How AI Challenges the Open Source Way
byIcinga
 
PDF
NTG -Company Profile_Software_Vendor_Company_in_MENA
byMustafa Kuğu
 
PDF
Traditional-Security-Models-No-Longer-Work.pptx (1).pdf
byOhhproJunction
 
PPTX
TechSprint Inauguration at SJB Institute of Technology held on 18 December 2025
bysuhasspgdg
 
PDF
Rustici Software: eLearning standards in the age of AI
byRustici Software
 
PDF
Analyze and Preserve Logs - RHCSA (RH134).pdf
byLinuxCert Guru
 
The Emergence of Empathic XR: AWE Asia 2026 keynote
byMark Billinghurst
 
AI for Risk Management & Fraud Detection ppt.pdf
byalexmartincaneda
 
UiPath Automation Developer Associate Training Series 2026 - Session 1
byDianaGray10
 
apidays Paris 2025 | Integration is Feminist: Building Peace in Distributed S...
byapidays
 
Mesh WiFi Router: The Smart Solution for Fast, Seamless, Whole-Home Internet
byAeroMesh Systems
 
Startup Formation Collapses While Acquisition Activity Hits New High!
byMemoori
 
TravelTech Paris 2025 | The EU Digital Identity Wallet and it’s impact on Tra...
byapidays
 
The Manifesto for AI-enabled Governance !
byYannis Charalabidis
 
Self-Correction Failure Diagnostic: Detecting Drift in Complex Systems
bySystems Research Group
 
Introduction to Artificial Intelligence (AI).pptx
byammar414783
 
Designing a Blog Using Wordpress
bymarkzubi50
 
Computer architecture, Computer architecture ,Computer architecture
bywaheedqazi123
 
GenerationAI Paris 2025 | City of Light (COL)
byapidays
 
How Does an ICO Launchpad Work Step-by-Step Breakdown.pptx
byTom Hardy S
 
Automation Without Apprentices: How AI Challenges the Open Source Way
byIcinga
 
NTG -Company Profile_Software_Vendor_Company_in_MENA
byMustafa Kuğu
 
Traditional-Security-Models-No-Longer-Work.pptx (1).pdf
byOhhproJunction
 
TechSprint Inauguration at SJB Institute of Technology held on 18 December 2025
bysuhasspgdg
 
Rustici Software: eLearning standards in the age of AI
byRustici Software
 
Analyze and Preserve Logs - RHCSA (RH134).pdf
byLinuxCert Guru
 

Impedance Spectroscopy

  • 1.
    Advances in impedancespectroscopy of solar energy conversion devices Juan Bisquert Photovoltaic and Optoelectronic Devices Group Universitat Jaume I 12071 Castelló Spain 27 10 2012
  • 2.
  • 3.
  • 4.
    Photovoltaics: Charge separation Bisquert,J.; Cahen, D.; Rühle, S.; Hodes, G.; Zaban, A. "Physical chemical principles of photovoltaic conversion with nanoparticulate, mesoporous dye-sensitized solar cells." The Journal of Physical Chemistry B, 108, 8106, 2004.
  • 5.
    Fundamental model fora solar cell Infinite mobilities- no transport resistance Fermi level straight inside Perfect selective contacts 1. Generation 2. Recombination Fermi level fixed inside by 3. Extraction external potential, independent of illumination Bisquert, J.; Cahen, D.; Rühle, S.; Hodes, G.; Zaban, A. "Physical chemical principles of photovoltaic conversion with nanoparticulate, mesoporous dye-sensitized solar cells." The Journal of Physical Chemistry B, 108, 8106, 2004.
  • 6.
    The diode equationfor a solar cell Dark At V = 0 equilibrium of generation and recombination jr (0) = j0 Rise of the Fermi level enhances recombination jr (V ) = j0 e qV / mk BT Sunlight Equilibrium of generation and recombination j = jsc + j0 − j0 e qV / mk BT Can be measured directly by Also can be expressed in terms of carrier density recombination resistance
  • 7.
  • 8.
  • 9.
  • 10.
    Dye-sensitized solar cell Nayak,Kahn, Garcia.Belmonte, Bisquert, Cahen, Energy and Environmental Science 2012
  • 11.
    Limitation to efficiency TheDSC It is a 3 –materials solar cell There is a price of energy differences, but more versatile and potentially cheap
  • 12.
    Influence of energetics:higher Voc If the conduction band of TiO2 is higher, the Fermi level can rise higher (in principle) and photovoltage may become larger
  • 13.
    Influence of energetics:photocurrent If the conduction band of TiO2 is higher, there is less injection from the dye molecules, and current decreases
  • 14.
    The redox potentialof the hole conductor New redox couples? The Fermi level of the hole conductor is lower than I-/I3- liquid electrolyte, which gives higher photovoltage
  • 15.
  • 16.
    Diffusion-recombination transmission linemodel J. Bisquert, J. Phys. Chem. B 106, 325-333 (2002) F. Fabregat-Santiago, J. Bisquert, G. Garcia-Belmonte, G. Boschloo, A. Hagfeldt Solar En. Mat. Sol.Cells, 87, 117-131 (2005).
  • 17.
    Measurement of resistancesand capacitances by Impedance Spectroscopy
  • 18.
    DSC device ISmodel J. Bisquert, J. Phys. Chem. B 106, 325-333 (2002) F. Fabregat-Santiago, J. Bisquert, G. Garcia-Belmonte, G. Boschloo, A. Hagfeldt Solar En. Mat. Sol.Cells, 87, 117-131 (2005).
  • 19.
    How do wedetermine energetics? The chemical capacitance measures the density of states in the bandgap (DOS) and this provides a reference of the Ec in different cells. Pt TCO re d o x e le c t r o ly t e T iO 2 E C E Fn e le c tr ic p o te n tia l e le c tr o n e n e r g y eV E F0 E re d o x
  • 20.
    Chemical capacitance The conduction band of TiO2 is situated at a given level with respect to the Fermi level of hole conductor. The chemical capacitance measures the density of states in the bandgap (DOS) and this provides a reference of the Ec in different cells. TC O re d o x Pt Chemical capacitance e le c t r o ly t e T iO 2 E C ∂n E Fn Cµ = q 2 e le c t r ic p o t e n t ia l e le c t r o n e n e r g y eV ∂E Fn E F0 E re d o x Bisquert, J. "Chemical capacitance of nanostructured semiconductors: its origin and significance for heterogeneous solar cells". Phys. Chem. Chem. Phys. 2003, 5, 5360
  • 21.
    Interpretation of recombination resistance '  q VF  Rrec = R0 exp − β  k BT   The model considers a distribution of surface states, and charge transfer via Marcus model 1 T β= + α s = 0. 5 + 2 T0 s Q. Wang, M. Grätzel, F. Fabregat-Santiago, J. Bisquert et al., J. Phys. Chem. B. 110, 25210-25221 (2006) J. Bisquert, F. Fabregat –Santiago, I. Mora-Seró, G. Garcia-Belmonte, S. Giménez, J. Phys. Chem. C, 113, 17278 (2009).
  • 22.
    Fill factors The recombinationorder β relates directly to the diode ideality factor m = 1.5-2.5 j = jsc + j0 − j0e qβV / k BT Restrictions on the fill factor
  • 23.
    Shif of theband changes the diode factor Jennings and Wang show that the diode factor changes when the conduction band is brought down by the addition of lithium. m = 1 at high lithium content (low cb position) Because electron transfer is from conduction band and linear recombination occurs J. Jennings, Q. Wang J. Phys. Chem. C, 114, 1715 (2010).
  • 24.
    The diffusion length Thediffusion coefficient is related only to resistances Rrec Ln = Dnτ n = L Rtr J. Bisquert, J. Phys. Chem. B, 106, 325-333 (2002)
  • 25.
    Variations of thediffusion length The diffusion length increases with the bias This is indicating that the free electron lifetime is not a Ln = Dnτ n = D0τ f constant Quantitative description is made by Peter et al. Using nonlinear recombination model J. Villanueva-Cab, H. Wang, G. OskamL. M. Peter, J. Phys. Chem. Lett. 1, 748, (2010).
  • 26.
    Phtalocyanine dyes O O O O O O O O N N N N N N H N Zn N N N H N N N N N N O O O O O O O O O O ZnPc-1 H2Pc-2 Barea, E. M.; Ortiz, J.; Payá, F. J.; Fernández-Lázaro, F.; Fabregat-Santiago, F.; Sastre-Santos, A.; Bisquert, J. "Energetic factors governing injection, regeneration and recombination in dye solar cells with phthalocyanine sensitizers". Energy and Environmental Science 2010, 3, 1985
  • 27.
    Phtalocyanine dyes n at VOC EC EC - EFn Voc jsc η Sample FF (cm-3) (eV) (eV) (V) (mA/cm2) (%) ZnPc-1 0.44 3.48 0.66 1.01 4.2 x 1017 -4.00 0.31 H2Pc-2 0.35 5.71 0.57 1.14 1.5 x 1018 -4.13 0.27 N719 0.45 10.90 0.51 2.50 3.0 x 1018 -4.11 0.19 Barea, E. M.; Ortiz, J.; Payá, F. J.; Fernández-Lázaro, F.; Fabregat-Santiago, F.; Sastre-Santos, A.; Bisquert, J. "Energetic factors governing injection, regeneration and recombination in dye solar cells with phthalocyanine sensitizers". Energy and Environmental Science 2010, 3, 1985
  • 28.
    Phtalocyanine dyes The bandis shifted for ZnPC We move the potential scale to compare recombination ZnPc has more recombination Recombination in H2Pc is the same as in N719
  • 29.
    Phtalocianyne dyes Recombination inH2Pc is the same as in N719 With the same current it would give the same voltage Barea, E. M.; Ortiz, J.; Payá, F. J.; Fernández-Lázaro, F.; Fabregat-Santiago, F.; Sastre-Santos, A.; Bisquert, J. "Energetic factors governing injection, regeneration and recombination in dye solar cells with phthalocyanine sensitizers". Energy and Environmental Science 2010, 3, 1985
  • 30.
    The DOS anessential reference to explain performance Explanation of the low VOC. 1)an inefficient injection 2)the low position of the conduction band of TiO2,
  • 31.
    Identifying the rolethat the dye structure plays in DSC performance why YD2 porphyrin dye Acceptor• Can achieve such a high performance group close to that of a Ru commercial dye? Donor group Besides of the dye structure and the related photophysical properties. bridge •What other key parameters in a DSC influence YD2 strongly the overall power conversion efficiency? Diau, C.-Y. Yeh, J. Mater. Chem. 2010, 20, 1127 Angew. Chem. Int. Ed. 2010, 49, 6646 –6649
  • 32.
    YD2 YD0 Sample name YD2 YD0 N719 Current density (mA·cm ) N719 Voc (V) -2 15 0.66 0.65 0.74 jsc (mA/cm2) 15.4 6.92 12.6 10 FF 0.62 0.73 0.70 Efficiencysame condictions 7% efficiency is the record * Under (%)* 6.36 3.29 6.54 5 0 0.0 0.2 0.4 0.6 0.8 Potential (V) N719 Barea, E. M.; Gonzalez-Pedro, V.; Ripolles-Sanchis, T.; Wu, H.-P.; Li, L.-L.; Yeh, C.-Y.; Diau, E. W.-G.; Bisquert, J. "Porphyrin Dyes with High Injection and Low Recombination for Highly Efficient Mesoscopic Dye-Sensitized Solar Cells". The Journal of Physical Chemistry C 2011, 115, 10898
  • 33.
    J. Phys. Chem.B 2006, 110, 25210-25221 10-2 105 (a) (b) -2 Capacitance / F·cm 104 2 Rrec / Ohms·cm 10-3 103 102 10-4 101 10-5 100 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Applied Potential / V Applied Potential / V
  • 34.
    N719 Sample name YD2 YD0 N719 Voc (V) 0.66 0.65 0.74 jsc (mA/cm2) 15.4 6.92 12.6 FF 0.62 0.73 0.70 Efficiency (%) 6.36 3.29 6.54
  • 35.
    Sample name YD2 YD0 N719 Voc (V) 0.66 0.65 0.74 jsc (mA/cm2) 15.4 6.92 12.6 FF 0.62 0.73 0.70 Efficiency (%) 6.36 3.29 6.54 β 0.47 0.73 0.70 j0 (mA/cm2) 7.75e-05 6.09e-08 2.09e-08 j0k (mA/cm ) 2 54 1406 213 α 0.29 0.30 0.24 ∆Ec vs ref (mV) -123 -32.0 Ref Rseries (ohm) 19.5 19.4 17.9 Internal FF 0.73 0.81 0.81 Internal efficiency (%) 7.41 3.58 7.54 Barea, E. M.; Gonzalez-Pedro, V.; Ripolles-Sanchis, T.; Wu, H.-P.; Li, L.-L.; Yeh, C.-Y.; Diau, E. W.-G.; Bisquert, J. "Porphyrin Dyes with High Injection and Low Recombination for Highly Efficient Mesoscopic Dye-Sensitized Solar Cells". The Journal of Physical Chemistry C 2011, 115, 10898
  • 36.
    • ISTPro Features - Analyzes IS data of dye-sensitized solar cells (DSC). - Allows to treat impedance spectroscopy parameters to obtain the essential parameters of the DSC performance. - Display the
  • 37.
  • 38.
  • 39.
  • 40.
    Organic solar cells Sunflowerproject: http://sunflower-fp7.eu
  • 41.
    Organic solar cell OnVoltage, Photovoltage, and Photocurrent in Bulk Heterojunction Organic Solar Cells Juan Bisquert and Germa Garcia-Belmonte, J. Phys. Chem. Lett. 2011, 2, 1950–1964
  • 42.
    Organic solar cell Ratcliff,E. L.; Zacher, B.; Armstrong, N. R. "Selective Interlayers and Contacts in Organic Photovoltaic Cells". The Journal of Physical Chemistry Letters 2011, 2, 1337.
  • 43.
    The bands andthe Fermi levels Dielectric (depletion) capacitance The chemical capacitance
  • 44.
    Band bending andFermi levels Donor LUMO Acceptor LUMO EF Donor HOMO --- -- -- Cathode Acceptor HOMO w V=0
  • 45.
    Band bending andFermi levels Donor LUMO Acceptor LUMO EF Donor HOMO -- -- Cathode Acceptor HOMO w V < Vfb
  • 46.
    Band bending andFermi levels Donor LUMO Acceptor LUMO EF Donor HOMO --- Cathode Cathode Acceptor HOMO w V < Vfb
  • 47.
    Band bending andFermi levels Donor LUMO Acceptor LUMO EF Donor HOMO - Cathode Acceptor HOMO w V < Vfb
  • 48.
    Band bending andFermi levels Donor LUMO Acceptor LUMO EF Donor HOMO Cathode Acceptor HOMO V = Vfb
  • 49.
    Depletion region –Mott Schottky plots Increase in the capacitance caused by the reduction of the depletion zone Characterization of nanostructured hybrid and organic solar cells by impedance spectroscopyw Francisco Fabregat-Santiago, Germa Garcia-Belmonte, Ivan Mora-Sero´ and Juan Bisquert Phys. Chem. Chem. Phys., 2011, 13, 9083–9118
  • 50.
    Depletion region -P. P.Boix, G. Garcia-Belmonte, U. Muñecas, M.Neophytou, C. Waldauf, R. Pacios, Appl Phys. Lett 95, 1, (2009)
  • 51.
  • 52.
    Additional proofs ofelectrical field confined near the cathode FIG. 2. (Color online) (a) The mean-field potential line-profile of the cross-sectional image and (b) the corresponding energy band diagram after contacting of all layers. Appl. Phys. Lett. 99, 243301 (2011) © 2011 American Institute of Physics
  • 53.
    Measured DOS oforganic BHJ Measurement of the DOS The chemical capacitance ∂nL Cµ ( E ) = q 2 = qg n ( E Fn ) ∂EFn PCBM-P3HT solar cell Germà Garcia-Belmonte, Pablo P. Boix, Juan Bisquert, Michele Sessolo, and Henk J. Bolink Solar Energy Materials and Solar Cells, 94, 366 (2010)
  • 54.
    Comparison of differentfullerenes with similar reduction potential but different DOS DPM6 PCBM Higher Voc related to full occupancy of intermediate electronic band G. Gar Germa Garcia-Belmonte Pablo P. Boix, Juan Bisquert, Martijn Lenes, Henk J. Bolink, Andrea La Rosa, Salvatore Filippone,and Nazario Martín§,J. Phys. Chem. Lett. 1 (2010) 2566-2571
  • 55.
    Carrier diffusion inorganic BHJ PCBM-P3HT solar cell Diffusion-Recombination Determines Collected Current and Voltage in Polymer:Fullerene Solar Cells Teresa Ripolles-Sanchis, Antonio Guerrero, Juan Bisquert, and Germà Garcia-Belmonte, J. Phys. Chem. C 2012, 116, 16925−16933
  • 56.
    The Fermi levelin the Gaussian distribution In the presence of a Gaussian distribution, the carriers do not lie below the Fermi level. Bisquert, J. "Interpretation of electron diffusion coefficient in organic and inorganic semiconductors with broad distributions of states". Physical Chemistry Chemical Physics 2008, 10, 3175
  • 57.
    Why is Vocless than HOMO-LUMO difference? This is explained by disorder qVoc = E Fn − E Fp σ n2 + σ p2  Nn N p  qVoc = E g − − k BT ln  np   2k BT   This formula derived by G. Garcia-Belmonte quantifies the energy loss related to disorder Garcia-Belmonte, G. "Temperature dependence of open-circuit voltage inorganic solar cells from generation–recombination kinetic balance". Solar Energy Materials and Solar Cells 2010, 94, 2166
  • 58.
  • 59.
    Energetics of recombination Guerrero,A.; Marchesi, L. F.; Boix, P. P.; Bisquert, J.; Garcia-Belmonte, G. "Recombination in Organic Bulk Heterojunction Solar Cells: Small Dependence of Interfacial Charge Transfer Kinetics on Fullerene Affinity". The Journal of Physical Chemistry Letters 2012, 3, 1386
  • 60.
    Reconstruction of currentvoltage curves from recombination resistance data Boix, P. P.; Guerrero, A.; Marchesi, L. F.; Garcia-Belmonte, G.; Bisquert, J. "Current-Voltage Characteristics of Bulk Heterojunction Organic Solar Cells: Connection Between Light and Dark Curves". Advanced Energy Materials 2011, 1, 1073
  • 61.
    Reconstruction of currentvoltage curves from recombination resistance data −1 k BT  dj  jsc = j rec (Voc ) = L Rrec = L rec   dV  βqRrec (Voc )  F  Boix, P. P.; Guerrero, A.; Marchesi, L. F.; Garcia-Belmonte, G.; Bisquert, J. "Current-Voltage Characteristics of Bulk Heterojunction Organic Solar Cells: Connection Between Light and Dark Curves". Advanced Energy Materials 2011, 1, 1073
  • 62.
  • 64.
    Charge Transfer, Transportand Recombination Processes T1→ e- transport R4 T2→ h+ transport I1→ e- injection from QD CB I2→ e- injection from QD trap I1 R5 I3→ e- back injection to QD T1 I2 I4 → h+ injection from QD CB Tr3 I3 Tr1 R1 I5 → h+ injection from QD trap Tr1→ e- trapping in the QD R2 T2 R3 Tr2 → h+ trapping in the QD I4 R1→ e-- h+ band-to-band Tr2 I5 recombination in the QD R2→ e-- h+ trap mediated recombination in the QD Electron QD Hole R3→ recombination of e- in the Transporter Transporter TiO2 with h+ in the QD R4→ recombination of e- in the TiO2 with h+ in the HT R5→ recombination of e- in the QD with h+ in the HT - G. Hodes, J. Phys. Chem. C 2008, 112, 17778–17787
  • 65.
    Quantum dot solarcells Boix, P. P.; Larramona, G.; Jacob, A.; Delatouche, B.; Mora-Seró, I.; Bisquert, J., Hole Transport and Recombination in All-Solid Sb2S3-Sensitized TiO2 Solar Cells Using CuSCN As Hole Transporter. Journal of Physical Chemistry C 2012, 116, 1579–1587..
  • 66.
    Sensitizer Material PbS/CdS CdS PbS Combination of different kinds of QDS increases dramatically cell performance. Braga et al., J. Phys. Chem. Lett. 2011, 2, 454–460
  • 67.
    Surface treatment Effect Surface treatments have a dramatic effect on solar cell performance Barea et al. J. AM. CHEM. SOC. 2010, 132, 6834–6839
  • 68.
  • 69.
    Water splitting cell Energy diagram of a PEC cell for the photo-electrolysis of water. The cell is based on an n-type semiconducting photo-anode. Gerischer, H. "The impact of semiconductors on the concepts of electrochemistry". Electrochimica Acta 1990, 35, 1677-1699
  • 70.
    Semiconductor photoelectrochemistry Reichman Appl. Phys. Lett. 1980, 36, 574
  • 71.
    Hematite GrätZel et alJ. AM. CHEM. SOC. VOL. 132, 2010
  • 72.
    Photogeneration of electronsand holes Charge transfer via surface states Carrier density and interfacial kinetics in mesoporous TiO 2 during water splitting determined by impedance spectroscopy Sixto Giménez, J. Electroanal Chem 2012
  • 73.
    Water splitting cell Simplemodel of a photoelectrochemical cell Bertoluzzi, L.; Bisquert, J. "Equivalent Circuit of Electrons and Holes in Thin Semiconductor Films for Photoelectrochemical Water Splitting Applications". The Journal of Physical Chemistry Letters 2012, 3, 2517
  • 74.
    Equivalent circuit Simple modelof a photoelectrochemical cell Bertoluzzi, L.; Bisquert, J. "Equivalent Circuit of Electrons and Holes in Thin Semiconductor Films for Photoelectrochemical Water Splitting Applications". The Journal of Physical Chemistry Letters 2012, 3, 2517
  • 75.
    Thin hematite layer JV curve and impedance model Klahr, B.; Gimenez, S.; Fabregat-Santiago, F.; Hamann, T.; Bisquert, J. "Water Oxidation at Hematite Photoelectrodes: The Role of Surface States". Journal of the American Chemical Society 2012, 134, 4294
  • 76.
    impedance results Klahr, B.;Gimenez, S.; Fabregat-Santiago, F.; Hamann, T.; Bisquert, J. "Water Oxidation at Hematite Photoelectrodes: The Role of Surface States". Journal of the American Chemical Society 2012, 134, 4294
  • 77.
    Impedance model andresults Klahr, B.; Gimenez, S.; Fabregat-Santiago, F.; Hamann, T.; Bisquert, J. "Water Oxidation at Hematite Photoelectrodes: The Role of Surface States". Journal of the American Chemical Society 2012, 134, 4294
  • 78.
    Other redox couple water Fe(CN)6]3-/4- With [Fe(CN)6]3-/4- in solution, however, the charge transfer resistance is essentially constant over the measured potential range for a given light intensity as shown in figure 4c. The absence of a measureable surface state capacitance and absence of a dip in the charge transfer resistance suggests that photooxidaiton of [Fe(CN)6]4- does not involve surface states and can be described as a simple outersphere Klahr, B.; Gimenez, S.; Fabregat-Santiago, F.; Bisquert, J.; Hamann, T. W. "Electrochemical and photoelectrochemical investigation of water oxidation with hematite electrodes". Energy & Environmental Science 2012, 5, 7626
  • 79.
    Surface treatment withCo-Pi Sivula et al., Energy Environ. Sci. 2011, 4, 1759 Durrant, Gratzel, et al JACS 2011
  • 80.
    Interpretation of Co-Pi Klahr,B.; Gimenez, S.; Fabregat-Santiago, F.; Bisquert, J.; Hamann, T. W. "Photoelectrochemical and Impedance Spectroscopic Investigation of Water Oxidation with Co-Pi -Coated Hematite Electrodes". Journal of the American Chemical Society 2012, 134, 16693
  • 81.

Editor's Notes

  • #18 Experimetal results showed a a negative shift. Therefore we can conclude that the impedance at these potentials is governed by the cap. of the uncovered CS and complete the model initially used with this.
  • #65 DSC  Light harvesting material  QDs benefits for a panchromatic sensitizer
  • #66 Absorption of light is inherently on the nanoscale Conventional materials such as Si and GaAs do a good job but are too expensive and can not be manufactured like printing the newspaper Nanomaterials offer the ability to get good light absorption in flexible formats Interpenetrating networks on the nanoscale offer the opportunity to get high performance charge collection from low cost materials