Low band gap thienothiophene-diketopyrrolopyrole copolymers with V2O5 as hole transport layer for photovoltaic application

The present article mainly focuses on the synthesis of copolymers alternating thienothiophene, diketopyrrolopyrrole based units with thiophene spacers were designed, synthesized and characterized. The synthesized polymers were characterized for thermal stability, structural and its photovoltaics properties. All the synthesized polymers showed good solution formability, exhibits high thermal stability up to 200 degrees C, and -1.8eV optical band gap. And also, the polymers synthesized using dithiophene spacer exhibit low energy band gap and hence broad optical absorption range. These polymers were used as a donors and PC61BM acceptor to fabricate the. Devices were fabricated for various solution concentration and ratios of donor: acceptor to attain the maximum achievable efficiency. For the preliminary optimized device condition the maximum obtained efficiencies is 1.06%, J(SC) is 66.3 Am-2, V-OC is 0.65 V and fill factor is 23.7%.