Fig. 4: Absorption spectra and photovoltaic performance of PTB7-Th:BTPV-4F.

a Normalized absorption spectra of blend films of PTB7-Th:BTPV-4F (1:1.5, w/w) and PTB7-Th:BTPV-4F:PC71BM (1:1.5:0.15, w/w/w). b The J–V curves of the optimized binary OSC based on PTB7-Th:BTPV-4F(1:1.5, w/w) and ternary OSC based on PTB7-Th:BTPV-4F:PC71BM (1:1.5:0.15, w/w/w). c The EQE spectra of the corresponding binary and ternary OSCs. d Plots of Jsc values of the OSCs vs. optical bandgaps of the narrow bandgap acceptors used in the OSCs reported in the literature and from this work with the acceptor of BTPV-4F.