Nitrile-Substituted QA Derivatives: New Acceptor Materials for Solution-Processable Organic Bulk Heterojunction Solar Cells

The development of non-fullerene-based electron acceptors (especially organic molecules with sufficient absorption property within the solar spectrum region) for bulk-heterojunction (BHJ) organic solar cells (OSCs) is an important issue for the achievement of high photoconversion efficiency. In this contribution, a new class of organic acceptors di-cyan substituted quinacridone derivatives (DCN-nCQA, n = 4, 6 and 8) for BHJ solar cells was designed and synthesized. DCN-nCQA molecules possess facile synthesis, solution processability, visible and near-IR light absorption and relatively stable characteristics. The DCN-8CQA molecule exhibited a proper LUMO energy level (-4.1 eV), small bandgap (1.8 eV) and moderate electron mobility (10(-4) cm(2) V-1 S-1), suggesting that this molecule is an ideal acceptor material for the classical donor material regio-regular poly (3-hexylthiophene) (P3HT). A photovoltaic device with a structure of [ITO/PEDOT:PSS/P3HT:DCN-8CQA/LiF/Al] displayed a power conversion efficiency of 1.57% and a fill factor of 57% under 100 mW cm(-2) AM 1.5G simulated solar illumination. The DCN-nCQA molecules showed remarkable absorption in the region from 650 to 700 nm, where P3HT has a weak absorption promoting overlap with the solar spectrum and potentially improving the performance of the solar cell.