Small molecular non-fullerene electron acceptors for P3HT-based bulk-heterojunction solar cells

Abstract

Three small molecules with the same arms and different cores of perylene diimide (PDI) or indaceno[2,1-b:6,5-b′]dithiophene (IDT) were designed and synthesized as the acceptor materials for P3HT-based bulk-heterojunction (BHJ) solar cells. The impacts of the different cores on the optical absorption, electrochemical properties, electron mobility, film morphology, photoluminescene characteristics, and solar cell performance were thoroughly studied. The three compounds possess a broad absorption covering the wavelength range of 400–700 nm and relatively low lowest unoccupied molecular orbital (LUMO) energy levels of −3.86, −3.81 and −3.99 eV. The highest power conversion efficiency of 0.82% was achieved for the BHJ solar cells based on SM3 as the acceptor material, the compound with a PDI core.