Department of Chemistry
Solution processable donor–acceptor oligothiophenes for bulk-heterojunction solar cells
Novel p-type and low bandgap penta- and hexa-thiophenes asymmetrically endcapped with solubilizing triarylamine or triarylamino-substituted carbazole dendron and dicyanovinyl groups, namely, PhNOF-OT(n)-DCN and G 2-OT(n)-DCN, respectively where n = 5-6 for solution-processable photovoltaic applications have been synthesized and investigated. With the incorporation of a solubilizing electron-donating group, the highly extended oligothiophenes are highly soluble in common organic solvents and solution-processable. Upon extending the oligothiophene backbone, there is a strong increase in the absorption around 420 nm in addition to the intramolecular charge-transfer absorption (520 nm) which results in a strong spectral broadening. The optical band-gap of these donor-acceptor oligothiophene thin-films greatly reduces to 1.85 eV. The solution-processed bulk heterojunction PV cells fabricated from these materials blended with PCBM as an acceptor showed a PCE up to 1.72% with Voc = 0.79 V in an as-fabricated device. Our findings also suggest that highly extended donor-acceptor oligomers can be useful for a p-type, low-bandgap semiconductor for solution-processable bulk heterojunction PV cells. © 2010 The Royal Society of Chemistry.
Source Publication Title
Journal of Materials Chemistry
Royal Society of Chemistry
Zhang, Weifeng, Shing Chi Tse, Jianping Lu, Ye Tao, and Man Shing Wong. "Solution processable donor–acceptor oligothiophenes for bulk-heterojunction solar cells." Journal of Materials Chemistry 20.11 (2010): 2182-2189.