All-Small-Molecule Nonfullerene Organic Solar Cells with High Fill Factor and High Efficiency over 10%

We synthesized two wide bandgap A–D–A structured p-type organic semiconductor (p-OS) small molecules with weak electron-withdrawing ester end groups: SM1 with cyano group (CN) on the ester group and SM2 without the CN group. SM1 showed stronger absorption, lower-lying HOMO energy level, and higher hole mobility in comparison with that of SM2 without the CN groups. The all-small-molecule organic solar cell (SM-OSC) with SM1 as donor and a narrow...