Influence of Solvent Additives on Stability, Performance and Morphology of Conjugated Polymer/Fullerene Based Organic Bulk Heterojunction Solar Cells

<p>Organic bulk heterojunction solar cells use polymer thin film technology which is cost effective, flexible and easily processable. P3HT:PCBM bulk heterojunction solar cell is most widely studied organic solar cell. Solvent additives have been shown to enhance power conversion efficiency, but its effect on stability is yet to be explored in detail. In this thesis the influence of 1,8-diiodooctane (DIO) additive, on the stability, performance and morphology of conjugated polymer (P3HT)/fullerene (PCBM) based solar cells was studied. In organic bulk heterojunction solar cells the majority of light is absorbed in the donor material. The incident photons are converted to excitons which get separated into holes and electrons at a donor/acceptor interface. Donor/acceptor regions can be optimized using techniques such as thermal annealing and solvent additives. Diiodooctane (DIO) solvent, 0%, 3% and 4% by vol., was added into a P3HT:PCBM blend during fabrication of the cells. The device structure used for this study was ITO/ PEDOT:PSS/ P3HT:PCBM/ Ca/ Al, where ITO was the transparent electrode and Al was the back electrode. The cells with DIO had 21% higher efficiency, shorter sweep-out time, higher IPCE, interpenetrating donor-acceptor morphology and higher hole mobility. A decrease in efficiency of 22% in 3% DIO vs. 62% for 0% DIO cells was observed with time. Aged cells with DIO had smaller donor/acceptor domains, higher hole mobility, lower sweep-out times and higher photocurrent generation compared to aged cells without DIO. Moreover, Raman data indicated aging affected the bonds in side chain but not the thiophene ring in P3HT. Thus DIO resulted in improved device performance and active layer morphology. The addition of DIO also enhanced stability in P3HT:PCBM bulk heterojunction solar cells.</p>

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Thesis - University Access Only

Discipline thesis:degree_discipline

Electrical Engineering and Computer Science

Year dc:date.available

2013

Author dc:creator

• Joshi, Presha

Contributors dc:contributor

• Venkat Bommisetty

• Power and Energy

Statement dc:rights

• <p>In Copyright - Non-Commercial Use Permitted<br /><a href="http://rightsstatements.org/vocab/InC-NC/1.0/">http://rightsstatements.org/vocab/InC-NC/1.0/</a></p>

Language dc:language

en

Repository record dc:identifier

https://openprairie.sdstate.edu/etd/1435

OAI identifier oai:identifier

oai:openprairie.sdstate.edu:etd-2436