Regulating the reorganization energy and crystal packing of small-molecule donors enables the high performance of binary all-small-molecule organic solar cells with a slow film growth rate

We develop three small-molecule donors (T25, T26 and T27) by stepwise terminal-group and side-chain engineering. The binary all-small-molecule organic solar cell (ASM-OSC) based on T27 : Y6 yields an efficiency of 16.8%, significantly higher than those based on T25 : Y6 (12.1%) and T26 : Y6 (14.0%).