Triphenylamine-cored star-shape compounds as non-fullerene acceptor for high-efficiency organic solar cells: Tuning the optoelectronic properties by S/Se-annulated perylene diimide

Three novel star-shaped S/Se-annulated perylene diimide (PDI) small molecule acceptors with triphe-nylamine as the core, namely TPA-PDI, TPA-PDI-S and TPA-PDI-Se, were designed and synthesized. Using the wideband-gap polymer PDBT-T1 as the donor and Se-annulated perylene diimide (TPA-PDI-Se) as the acceptor, power conversion efficiencies (PCE) of up to 6.10% was achieved, which is 38% higher than the reference of TPA-PDI without heteroatom annulation. Impressively, the S/Se-annulated perylene diimides as acceptors showed high open-circuit voltage (V-OC) of 1.00 V. The high efficiency for TPA-PDI-Se can be attributed to complementary absorption spectra with the donor material, relatively high-lying LUMO level, balanced carrier transport and favorable morphologies. To the best of our knowledge, this PCE of 6.10% is among the highest values based on star-shaped non-fullerene acceptors so far. (C) 2016 Elsevier B.V. All rights reserved.