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Title: | PERFORMANCE ANALYSIS OF BULK HETEROJUNCTION ORGANIC SOLAR CELLS |
Authors: | Pralhad, Salunkhe Rahul |
Keywords: | Organic Semiconductor Materials;Heterojunction Organic Solar Cells;Inorganic Counterparts;Metal- Insulator- Metal model |
Issue Date: | May-2016 |
Publisher: | IIT ROORKEE |
Abstract: | Organic semiconductor materials are of great interest due to their flexible nature and huge potential to act as an alternative to their inorganic counterparts for certain applications. The conductivity in them is originated from delocalization of 7t bonded electrons in organic molecules and the existence of conjugated systems. Solar cells are important devices in which the organic materials can be used. There are various rnorj)hOlOgieS of organic solar cells among which bulk hetero-junction is one of the best. Performance of the bulk heterojunction organic solar cells can be improved using better materials and a suit-able device structure. ITO/PEDOT:PSS/P3HT :PCBM blend/Al de-vice is simulated using Metal- Insulator- Metal model. Various device engineering are applied to analyse the performance and hence the opti-mization of the device parameters. The active layer thickness is one of the important parameter of organic photovoltaic cells. Generally it is in the order of few tens of nanometres and hence they are also termed as thin film solar cells in literature. Since the coefficient of optical ab-sorption of the active layer materials used in fabricating cells is finite, the layer thickness decides the percentage of photons absorbed by the cell, complex phenomenon such as exciton dissociation, excitori recom-bination, carrier recombination and hence the overall performance of * the cell. The P3HT:PCBM bulk heterojunction solar cell is simulated in Silvaco TCAD using simplified metal-insulator-metal model. The photocurrent, open circuit voltage, fill factor and efficiency are studied for the thicknesses from 20 nm to 200 nrn. As a result of the increa.se in percentage of photons absorbed with the higher thickness, the sig-nificant increase in photocurrent is observed. On the other hand fill factor is decreased as the higher thickness facilitates the carrier recombination probabihty. There is gradual increase in open circuit voltage with the thickness and it is justified using diode analogy of organic solar cell. The devices with different electrode materials are simulated and the effect of change in work functions of electrodes on the performance of bulk heterojunction devices is analysed. The electrode - active layer interfaces play very important role in the behaviour of the devices. The devices with different values of cathode-active layer and anode-active layer interface energy level offset are simulated and their current-voltage characteristics are analysed for the performance. The best case is observed in case of zero interface energy level offsets in case of the electrodes, anode and cathode. Fabrication steps for bulk heterojunction organic solar cells are discussed; devices are fabricated and characterized for dark characteristics. |
URI: | http://localhost:8081/jspui/handle/123456789/16859 |
metadata.dc.type: | Other |
Appears in Collections: | MASTERS' THESES (E & C) |
Files in This Item:
File | Description | Size | Format | |
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G25531.pdf | 9.03 MB | Adobe PDF | View/Open |
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