Fig. 1: Materials design and characterization.

a Molecular structures of the acceptors BTPV-4F and Y6. b Absorption spectra of the BTPV-4F and Y6 films. c Simulated optimal bandgap matching of two sub-cells in tandem OSCs. d Molecular structures of the acceptor m-DTC-2F and the polymer donors PTB7-Th and PM6.