Broadening the Photoresponse to Near-Infrared Region by Cooperating Fullerene and Nonfullerene Acceptors for High Performance Ternary Polymer Solar Cells.

Ternary polymer solar cells (PSCs) based on multiple materials with level matching and complementary absorptions are regarded as an efficient way to overcome the light-harvesting restriction to surpass high-performance binary PSCs. This study introduces the third component, nonfullerene acceptor IEICO, into binary PSC-based PBDTBDD:PC71 BM to fabricate ternary PSC with one donor and two acceptors. By carefully tuning the third component ratio and cathode engineering, the resulting ternary PSC shows a power conversion efficiency of 10.51%, greatly improved in comparison with binary PSCs-based PBDTBDD:PC71 BM (7.86%) and PBDTBDD:IEICO (5.19%). In addition to extended light absorption, the third component IEICO could accelerate charge-carrier transfer, decrease charge recombination, and increase electron collection, resulting from cascade energy levels, and ameliorate the device morphology to increase the contact area of the active layer and cathode buffer layer. This work demonstrates that ternary PSC incorporated with IEICO is a promising structure for producing high performance PSCs.