Nonfullerene acceptor with strong near-infrared absorption for polymer solar cells

A fused-ring electron acceptor based on indacenodithiophene was designed and synthesized. The nonfullerene acceptor shows strong absorption in 500-850 nm with extinction coefficient up to 1.4 x 10(5) M-1 cm(-1) and relatively high lowest unoccupied molecular orbital energy level (-3.55 eV). As an electron-cascade acceptor and strong absorption material; the new acceptor was incorporated into poly(3-hexylthiophene): [6,6]-phenyl-C-61-butyric-acidmethyl-ester blend to fabricate ternary blend polymer solar cells. The introduction of the nonfullerene acceptor can not only broaden the light absorption of the active layer to the near-infrared region, but also increase the open circuit voltage due to the higher lowest unoccupied molecular orbital of the nonfullerene acceptor relative to the fullerene acceptor. Ternary blend devices with 20% of the nonfullerene acceptor exhibited an average power conversion efficiency of 3.84%, higher than those of the binary blends using the fullerene acceptor (3.30%) or the nonfullerene acceptor (1.42%). (C) 2016 Elsevier Ltd. All rights reserved.973 Program [2013CB834702]; NSFC [91433114, 21504058]SCI(E)ARTICLE553-55913