Indolo[3,2-b]carbazole-based non-fullerene acceptors for organic photovoltaic cells

Abstract

Two indolo[3,2-b]carbazole-based non-fullerene acceptors (ICZ-IC and ICZ-ICF) with a A-π-D-π-A structure were synthesized by end-capping either non-fluorinated or fluorinated 1,1-dicyanomethylene-3-indanone into the indolo[3,2-b]carbazole (ICZ) core via the thiophene linker. Their photophysical and electrochemical properties were investigated. The photovoltaic device fabricated PBDB-T:ICZ-IC exhibited a maximum power conversion efficiency of 2.51% with an open-circuit voltage of 0.98 V without any post-treatment, while the photovoltaic device fabricated PBDB-T:ICZ-ICF showed a maximum power conversion efficiency of 1.26% with an open-circuit voltage of 0.82 V. By addition of chloronaphthalene and chlorobenzene solvent vapor annealing, the power conversion efficiency of the optimized device fabricated PBDB-T:ICZ-IC was increased to 3.20%.