A nonfullerene acceptor incorporating a dithienopyran fused backbone for organic solar cells with efficiency over 14%

Abstract An acceptor-donor-acceptor (A-D-A) type small molecule acceptor ITOT-4Cl incorporating a dithienopyran (DTP) fused backbone, has been designed and synthesized. With the strong electron-donating capability of the backbone D unit, ITOT-4Cl shows a narrow band gap of 1.28 eV, and has an efficient absorption in near-infrared region up to 968 nm. The photovoltaic devices based on PBDB-T:ITOT-4Cl give a power conversion efficiency (PCE) of 12.50%, with a high short circuit current density (Jsc) of 22.89 mA cm−2. With F–Br as the third component, the ternary organic solar cells device shows an enhanced PCE of 14.29% with an improved Jsc of 24.40 mA cm−2, which is among the best results for oxygen heterocycle fused nonfullerene acceptor based devices.