A Simple but Efficient Small Molecule with a High Open Circuit Voltage of 1.07 V in Solution‐Processable Organic Solar Cells

Acceptor–donor–acceptor (A–D–A) is an effective molecular design strategy for organic small molecules. In this work, we reported a simple A–D–A small molecule ( TBDT‐2HT‐ID ), with thiophene‐substituted benzodithiophene (TBDT) as a core, 1H‐indene‐1,3(2 H )‐dione (ID) as end‐capped acceptor, and linked by the π‐bridge of 3,6‐dihexylthieno[3,2‐b]thiophene. UV and CV results showed that the molecule exhibited good absorption in the range of 300–700 nm but a very low HOMO energy level (−5.47 eV). Grazing incidence X‐ray diffraction (GIXRD) results demonstrate it has good crystallinity and adopts an edge‐on molecular packing, and consequently its hole mobility could reach 1×10 −3  cm 2  V ‐1 S −1 . Based on PC 71 BM as acceptor, TBDT‐2HT‐ID had an excellent power conversion efficiency with 7.4 % without any post‐treatment, and a very high V oc of 1.07 V, which would be one of the highest V oc reported so far.