Synthesis and characterization of highly conjugated side‐group‐substituted benzo[1,2‐b:4,5‐b′]dithiophene‐based copolymer for use in organic solar cells

Abstract

A new donor-acceptor (D-A) conjugated copolymer based on benzo [1,2-b:4,5-b 0 ]dithiophene (BDT) and thieno [3,4c]pyrrole-4,6-dione (TPD) was synthesized via a Stille crosscoupling reaction. A highly conjugated thiophene-based side group, tris(thienylenevinylene) (TTV), was incorporated into each BDT unit to generate the two-dimensional D-A copolymer (PBDT-TTV). An alkoxy-substituted BDT-based TPD copolymer (PBDT-OR) was synthesized using the same polymerization method for comparison. PBDT-TTV thin films produced two distinct absorption peaks. The shorter wavelength absorption (458 nm) was attributed to the BDT units containing the TTV group, and the longer wavelength band (567-616 nm) was attributed to intramolecular charge transfer between the BDT donor and the TPD acceptor. The highest occupied molecular orbital energy levels of PBDT-OR and PBDT-TTV were V C 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 653-660

Research progress and application of high efficiency organic solar cells based on benzodithiophene donor materials

“…Afterward, to further enhancing the electronegative of TT unit, by creating two active sites and introducing the functional group carbonyl, 4H , 6H -5λ 2 -thieno [3, 4-c ] pyrrole-4,6-dione (TPD) unit with a strong electron-withdrawing was successfully constructed. Subsequently, based on the polymer backbone BDT-T-TPD-T, PBDT-TPD (2014) andPBDTT-TPD (2014) were designed by Kim et al [138] ; P1 (2016) , PBDT-Th-TPD (2017) , PBDT-TTV (2018) and PTPD (2020) were prepared by Kranthiraja et al [139] , Kotturappa et al [140] , Kim et al [141] , and Zhao et al [142] in turn; a series of polymer donors TPD-1 (2020) , TPD-2 (2020) , TPD-3 (2020) and TPD-3F (2020) were also synthesized by Liao et al [143] After applying for OSC devices, the introduction of thiophene-based and benzene-based side chains further extend the π-π conjugated plane of polymer donors, thereby these polymer donor: acceptor based OSC achieved a promisingV oc , especially for P1 (2016): PC 71 BM based OSC (0.99 V). Furthermore, based on the main chain of BDT-T-TPD-T, due to the substitution of alkyl-thiophene side chain extend the original π-π conjugated plane of polymer backbone as well as enhance the electron-donating of BDT unit, meanwhile, the introduction of long alkyl chain also optimized the miscibility and blend film morphology of active layer.…”