Fig. 5

a Chemical structures of PBBTzNTz polymers. b Δσ transients of PBBTzNTz:PCBM films at their optimal blend ratios measured by Xe-flash TRMC (λex = white light pulse). Each decay corresponds to the respective alkyl chain. c Current density vs. voltage curves of the PBBTzNTz:PCBM devices. Their PCE values are appended. Reproduced from [100] with permission (Copyright: 2017 American Chemical Society)