Semi-crystalline random conjugated copolymers with panchromatic absorption for highly efficient polymer solar cells

Abstract

An effective approach to extend the light absorption range of conjugated polymers for high performance photovoltaics is synthesis of copolymers composed of at least two different chromophores with a complementary absorption range. For this purpose, we synthesized random conjugated copolymers consisting of DPP and isoindigo as co-electron accepting units in donor–acceptor type conjugated copolymers. The random copolymers exhibited both broad light absorption and low-lying HOMO level, which contribute to enhancement of J_SC and V_OC, respectively. Furthermore, the predominant face-on orientation of the random copolymers on the substrate is beneficial for charge transport in the device. The polymer solar cell (PSC) based on the random copolymer has shown a promising efficiency of 6.04% which is the highest value among PSCs based on random copolymers.