New Donor-Acceptor polymers with a wide absorption range for photovoltaic applications. (15th July 2020)

• Record Type: Journal Article
• Authors: Keshtov, M.L.; Kuklin, S.A.; Konstantinov, I.O.; Ostapov, I.E.; Xie, Zh.; Koukaras, Emmanuel N.; Suthar, Rakesh; Sharma, Ganesh D.
• Is Part Of: Solar energy. Volume 205(2020)
• Page Start: 211
• Page End: 220
• Publication Date: 2020-07-15
• Subjects: Polymer solar cells -- Non-fullerene acceptors -- Power conversion efficiency -- Solvent vapor annealing; Solar energy -- Periodicals; Solar engines -- Periodicals; 621.47
• DOI: 10.1016/j.solener.2020.05.059
• Languages: English
• ISSNs: 0038-092X

Abstract

Graphical abstract: Highlights: Two D-A copolymers with the different acceptor DPP (P1) and CFCTP (P2) synthesized. Optical and electrochemical properties were influenced by the acceptor units. Fullerene and non-fullerene acceptors (PDIF) were used as electron acceptor. P2:PDIF based PSCs showed higher PCE (10.97%), than for the P1:PDIF (9.77%). Abstract: For conjugated polymers of interest in photovoltaic applications, control of the bandgap as well as the energy levels of the molecules are of great importance to improve the efficiency and performance of the resulting polymer solar cells. A general tactic for adjusting these properties via modification of the conjugated polymer structure is by using different and chosen molecular groups for copolymerization. This communication presents the synthesis of conjugated donor–acceptor type polymers that have the same benzotrithiophene (BTT) donor and different acceptor units, i.e. DPP and fluoro-carbazole substituted thieno[3, 4-b]pyrazine (FCTP) denoted as P(BTT-DPP) (P1 ) and P(BTT-FCTP) (P2 ), respectively, and their photovoltaic performance using as donor, and non-fullerene acceptor (PDIF) in the bulk heterojunction active layer. The bandgaps as well as the HOMO and LUMO energy levels are effectively tuned. The P(BTT-FCTPZ) structure exhibits a smaller bandgap as compared to P(BTT-DPP) that results from the lower LUMO energy and higher HOMO energy due to the FCTP unit. Having optimized the active layers, the PSCs that were based on P(BTT-DPP) and P(BTT-FCTPZ gave an overall power conversion efficiency of about 9.77% and 10.97%, respectively, using a wide bandgap PDIF non-fullerene acceptor, and 8.38% and 9.05, respectively, using PC71 BM as electron acceptor.