Double acceptor block-based copolymers for efficient organic solar cells: side-chain and π-bridge engineered high open-circuit voltage and small driving force. Issue 45 (5th November 2019)

• Record Type: Journal Article
• Authors: Guo, Hui; Chen, Lie; Huang, Bin; Xie, Qian; Ding, Shanshan; Chen, Yiwang
• Is Part Of: Polymer chemistry. Volume 10:Issue 45(2019)
• Page Start: 6227
• Page End: 6235
• Publication Date: 2019-11-05
• Subjects: Polymers -- Periodicals; Macromolecules -- Periodicals; Polymerization -- Periodicals; 547.705
• DOI: 10.1039/c9py01114e
• Languages: English
• ISSNs: 1759-9954

Abstract

Abstract : Different from the traditional concept of donor–acceptor (D–A) structures, the newly reported acceptor1 –acceptor2 (A1 –A2 ) type copolymers has been regarded as an efficient approach to boost the open circuit voltage ( V oc ). Abstract : Different from the traditional concept of donor–acceptor (D–A) structures, the newly reported design strategy of acceptor1 –acceptor2 (A1 –A2 ) type copolymers has been regarded as an efficient approach to boost the open circuit voltage ( V oc ) of organic solar cells (OSCs). Herein, three A1 –A2 type copolymers PBDD-BTZ-1, PBDD-BTZ-2 and PBDD-BTZ-3 with a 1, 3-bis(thiophen-2-yl)-5, 7-bis(2-ethylhexyl)benzo-[1, 2- c :4, 5- c ′]dithiophene-4, 8-dione (BDD) derivative as the A1 unit and fluorine substituted benzotriazole (FTAZ) as the A2 unit are prepared for OSCs. Subtle modification on the side chain and π-bridge is found to cause a big difference on the photoelectric properties and the resulting device performance of these new double A copolymers. A deep HOMO level of −5.63 eV with an extremely small driving force of 0.06 eV is found to be obtained by the PBDD-BTZ-3 copolymer. As a result, an impressive V oc of 1.09 eV is obtained when it was blended with an ITIC-Th acceptor. On the other hand, the best device performance is achieved by the PBDD-BTZ-2 copolymer among these copolymers, due to its most favorable morphology. These results suggest that A1 –A2 type copolymers can enrich the types of donor materials and will open a new possibility for developing efficient copolymers to boost the V oc of OSCs with a small driving force by reasonable combination of different electron-deficient blocks.