Synthesis of novel diketopyrrole and selenophene containing nir absorbing polymers and their application in bulk-heterojunction solar cells

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2017
Öklem, Gülce
DPP-based conjugated polymers are recently used in organic light emitting diodes, electrochromic devices, organic field effect transistor and organic solar cell applications. Their advantageous properties, such as broad optical absorption in Near Infra Red (NIR) region, high charge carrier mobility and good film forming ability make them an excellent choice for generation of highly efficient solar cells. In this thesis, using donor-acceptor approach (D-A) we aimed to synthesize novel polymers with furan based DPP units as the acceptor and selenophene as the donor. Modulating the alkyl side chains on furan based DPP cores, we obtained three different monomers which coupled with selenophene via Stille Coupling. Oxidation and reduction behaviors of the synthesized polymers were studied with cyclic voltammetry. Optical absorption properties of the polymers were investigated. Bulk heterojunction solar cell application of one of these polymers, P3 was performed with polymer/PCBM (1:3) ratio and the devices were fabricated with the structure ITO/PEDOT:PSS/P3:PCB71M/LiF/Al. Additionally, Inverted type bulk heterojunction solar cell application of P3 was also performed with device structure ITO/ZnO/P3:PC71BM/MoOx/Ag. While 3.00 % conversion efficiency was observed for the normal structure, a respectable 6.16 % efficiency was reached in the inverted structure with 3% diphenylether additive. This is one of the highest PCE reported for DPP based polymers.

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Citation Formats
G. Öklem, “Synthesis of novel diketopyrrole and selenophene containing nir absorbing polymers and their application in bulk-heterojunction solar cells,” M.S. - Master of Science, Middle East Technical University, 2017.