Synthesis of 3H-Benzo[e]indoline and Its Application to Small-Molecule Organic Solar Cells.

A squaraine-based small molecule (USQ-BI) bearing 3H-benzo[e]indoline was synthesized as an electron donor, and the corresponding organic solar cells show power conversion efficiency of 5.35 % with an excellent short circuit current of over 15 mA cm-2 . The hole mobility of USQ-BI was about 5 times (9.57×10-5 vs. 2.00×10-5  cm2  V-1  s-1 ) higher than that of indoline-based squaraine.