Novel conjugated polymers based on cyclopenta[c]thiophene-4,6(5H)-dione for efficient polymer solar cells

Abstract

A series of polymers based on indandione derivatives, TIND-HT-BDT, TIND-HT-BDTF, TIND-DHT-BDT, and TIND-DHT-BDTF, were synthesized as donor materials for polymer solar cells (PSCs). The polymers have a typical donor-acceptor configuration, where TIND-HT (5-((5-hexylthiophen-2-yl)methylene)-4H-cyclopenta[c]thiophene-4,6(5H)-dione) and TIND-DHT (5-((4,5-dihexylthiophen-2-yl)methylene)-4H-cyclopenta[c]thiophene-4,6(5H)-dione) are the electron acceptor units, while benzodithiophene (BDT) or fluorinated benzodithiophene (BDTF) are the electron donor units. Non-fullerene inverted-type PSCs with a configuration of ITO/ZnO/polymer:Y6BO/MoO3/Ag devices based on polymers as the donor and Y6BO as the acceptor were fabricated. The best power conversion efficiency (PCE) of 11.1% was achieved using the inverted-type PSCs based on TIND-DHT-BDTF with an open-circuit voltage (Voc) of 0.82 V and short-circuit current density (Jsc) of 22.6 mA/cm2. This study provides insights into novel donor materials for non-fullerene PSCs.