This document discusses the use of carbon nanotubes in solar panels to improve efficiency. It provides background on solar panels and carbon nanotubes, explaining their properties. It then details the history of carbon nanotube solar panels, how they are constructed, and how double-walled carbon nanotubes can be used as both light absorbers and charge carriers. Using carbon nanotubes allows solar panels to utilize infrared light and increase efficiency to potentially 80%. Their properties like high mobility and strength make them suitable for more efficient solar energy conversion.

1. At
GURUKUL INSTITUTE OF ENGINEERING AND TECHNOLOGY , RANPUR ,
KOTA
Submitted to : Submitted by:
Mr. Deepesh Namdev Daksh Joshi
HOD : EE & EC Roll No : 12EGKEE030
B. Tech Electrical VIII sem

2. A Simple View Of Carbon Nano Tubes :

3. Contents :
 Introduction
 Solar Panels
 Carbon Nanotubes
 Images related to CNT
 History of CNT solar panels
 Construction of carbon Solar cell
 Working of carbon solar cell
 Working of double walled CNT used in solar/photovoltaic cell
 Performance of CNT’s
 Advantages of using CNT in solar panel
 Conclusion

4. Introduction :
 The need for power in remote locations has given rise to the need for a more
portable solar cell.
 Organic solar cells have shown great potential for the solution.
 The problem lies in the inadequate efficiency currently found in organic
solar cells.
 Solar cells see only a portion of solar radiation .
 Approximately 20 percent of the energy contained in the solar spectrum is
unavailable to cells made of silicon .
 They are unable to utilize a part of the infrared radiation, the
shortwavelength IR radiation, for generating power.

5. Solar Panels :
 A solar panel is a set of solar photovoltaic modules electrically connected
and mounted on a supporting structure. A photovoltaic module is a
packaged, connected assembly of solar cells. The solar panel can be used as
a component of a larger photovoltaic system to generate and supply
electricity in commercial and residential applications. Each module is rated
by its DC output power under standard test conditions (STC), and typically
ranges from 100 to 320 watts. The efficiency of a module determines the
area of a module given the same rated output - an 8% efficient 230 watt
module will have twice the area of a 16% efficient 230 watt module. A
single solar module can produce only a limited amount of power; most
installations contain multiple modules. A photovoltaic system typically
includes a panel or an array of solar modules, an inverter, and sometimes a
battery and/or solar tracker and interconnection wiring .

6. Fig.1: An installation of 24 solar modules in rural Mongolia

7. Carbon Nanotubes:
 Carbon nanotubes (CNTs) are allotropes of carbon with a cylindrical
nanostructure. Nanotubes have been constructed with length-to-diameter
ratio of up to 132,000,000:1, significantly larger than for any other material.
These cylindrical nanotubes have unusual properties, which are valuable for
nanotechnology, electronics, optics and other fields of technology. In
particular, owing to their extraordinary thermal conductivity and mechanical
and electrical properties, carbon nanotubes find applications as additives to
various structural materials. For instance, nanotubes form a tiny portion of
the material(s) in some (primarily carbon fiber) baseball bats, golf clubs, or
car parts.
 These carbon nanotubes are now used in the technology of solar panels to
increase the efficiency of the solar panels up to 80%. The discussion
mentioned ahead will help in understanding how these carbon nanotubes
can be used in solar panels.

8. Images related to CNT :
Fig.2: A scanning electron microscopy image of carbon
nanotubes bundles.
Fig.3: Multi walled carbon nanotube

9. History Of CNT Solar Panels :
 Stanford University scientists have built the first solar cell made entirely of
carbon, a promising alternative to the expensive materials used in
photovoltaic devices today.The results are published in today's online
edition of the journal ACS Nano. It was later also developed by the
scientists in MIT. They could tap the unused energy of infrared radiations in
the modified solar cells using carbon nanotubes.
 Usage Of Carbon Nanotubes In Solar Pannels Helping In Improving The
Efficiency : The new cell is made of two exotic forms of carbon: carbon
nanotubes and C60, otherwise known as bucky balls. This is the first all-
carbon photovoltaic cell, a feat made possible by new developments in the
large-scale production of purified carbon nanotubes. It has only been within
the last few years or so that it has been possible to hand someone a vial of
just one type of carbon nanotube.

10. In order for the new solar cells to work, the nanotubes have to be very pure, and
of a uniform type: single-walled, and all of just one of nanotube two possible
symmetrical configurations. Other groups have made photovoltaic (PV) cells
using carbon nanotubes, but only by using a layer of polymer to hold the
nanotubes in position and collect the electrons knocked loose when they absorb
sunlight. But that combination adds extra steps to the production process, and
requires extra coatings to prevent degradation with exposure to air. The new all-
carbon PV cell appears to be stable in air. The carbon-based cell is most effective
at capturing sunlight in the near-infrared region. Because the material is
transparent to visible light, such cells could be overlaid on conventional solar
cells, creating a tandem device that could harness most of the energy of sunlight.
Fig.4: Fullerences (C60), Bunkyball

11. Construction Of Carbon Solar Cell :
 In conventional solid-state photovoltaic cells three different tasks are generally
expected to be fulfilled simultaneously by the material.
 Light absorption to generate electric charge carriers, charge carrier separation
and charge transport to the electrodes.
 We use a mixture of a stable photoactive light absorbing dye molecule with
carbon nanotubes introduced to a conjugated polymer matrix to perform these
tasks.
 Charge separation at the interface, electron transport through the carbon
nanotube acceptors and hole transport from the dye to the polymer backbone is
expected to occur.
 Transparent FTO coated glass (conducting glass) is to be used as bottom
electrode. The composite material dissolved in chloroform or toluene and
sonicated. The active layer can then be deposited by spin coating from the
solution.
 Complete device is obtained by depositing the top metal electrode by either
evaporation or sputtering techniques.

12. Fig.5: construction of the solar cell
Carbon is a remarkable element existing in a variety of stable forms
ranging from insulator/semiconductor diamond to metallic/semi-metallic
graphite to conducting/semi-conducting nano/micro tubes to fullerences of
highest order of symmetry, which shows many interesting physico-opto-
electronic properties.

13. Working of Carbon Solar Panel :
Solar panels works on the principal of photovoltaic effect.
PHOTOVOLTAIC EFFECT: It is the creation of an electrical voltage or rather
the electric current flowing in a closed loop, here referred to in a solar panel.
This process is somewhat related to the photoelectric effect; although these are
different processes altogether. The electrons that are generated when the solar
panels are exposed to a stream of photons are transferred between the different
bands of energy inside the atom to which they are bound. Typically, the
transition of the energy state of electrons takes place from valence band to the
conduction band, but within the material that is used in the solar panels. This
transfer of electrons makes them accumulate in order to cause a buildup of
voltage between the two electrodes.
Series connections of solar cells in solar panels help add up the voltage and the
saAnother fact is that solar panels produce much lesser efficiency as compared
to when their basic components viz. solar cells are used independently without
any interconnections. Typically, solar panels that are available commercially
are only able to depict their best efficiency as low as 21%.

14. Working Of Double Walled CNT Used In
Solar / Photovoltaic Cell :
The directly configured double-walled carbon nanotubes as energy conversion
materials to fabricate thin-film solar cells, with nanotubes serving as both photo
generation sites and a charge carriers collecting/transport layer. The solar cells
consist of a semitransparent thin film of nanotubes conformally coated on a n-
type crystalline silicon substrate to create high-density p−n heterojunctions
between nanotubes and n-Si to favor charge separation and extract electrons
(through n-Si) and holes (through nanotubes). Initial tests have shown a power
conversion efficiency of >1%, proving that DWNTs-on-Si is a potentially
suitable configuration for making solar cells. Our devices are distinct from
previously reported organic solar cells based on blends of polymers and
nanomaterials, where conjugate polymers generate excitons and nanotubes only
serve as a transport path.

15. Fig.6: working of solar panel.
NANOTUBE PROPERTIES USEFUL FOR SOLAR PANNELS
• High carrier mobilities (~1,20,000 cm2 V-1 s- 1)
• Large surface areas (~1600 m2 g-1)
• Absorption in the IR range (Eg: 0.48 to 1.37 eV)
• Conductance - Independent of the channel length
• Enormous current carrying capability – 109 A cm-2
• Semiconducting CNTs – Ideal solar cells
• Mechanical strength & Chemical stability

16. Performance Of CNT’s :
 When the CNT is used instead of the
pure polymer substances the
performance of the solar cell is as
shown below:
 It shows about the linear variation of
the V-I characteristics of the output
produced in the process of conversion
of the light energy to electrical energy.
 The variation of the wavelength, light
energy which is inputted to the panel
with the transmittance of that energy is
shown aside .
Fig. 7: variation of the wavelength over percentage transmittance.

17. Advantages Of Using CNT In a Solar Panel :
 The efficiency of the system can be improved.
 As the CNT solar panels uses infrared rays including visible range of
sunlight they can work at night times.
 They remain stable at ambience temperature about 1600oF .
 The amount of the material to be used for the construction will also be
reduced.
 As the mobility of the electrons is more in the case of the CNT the output
voltage produced is drastically increased.

18. Conclusion :
 Carbon nanotube technology is the upcoming
technology in the field of solar panels which is under
experimental stage.
 This seems likea very promising direction that will
eventually allow for nanotubes promise to be more
fully harnessed.
 It helps in increasing the efficiency, reliability of the
panel.

19. THANK YOU