Influence of fullerene-based acceptor materials on the performance of indacenodithiophene-cored small molecule bulk heterojunction organic solar cells

Abstract

A model system is presented to investigate the influence of fullerene-based acceptor materials on the performance of small molecule organic solar cells (SM-OSCs). Two indacenodithiophene-(IDT)-cored small molecules and one diketopyrrolopyrrole-(DPP)-cored molecule are used as donor materials, and two most widely applicable fullerene-based acceptors, [6,6]-phenyl-C61(71)-butyric acid methyl esters (PC61(71)BM) are used as the acceptor material, respectively. The charge generation, transport, and recombination behaviors were studied under various irradiation intensities, and these parameters are relevant to device performance. The transient photocurrent and transient photovoltage operation are utilized to directly compare the photo-induced absorption, charge generation, and charge recombination properties of the corresponding blend films. Our results indicate that different fullerene derivatives not only affect the device performance with their different light absorption abilities but also have roles in charge generation and charge recombination, which greatly helps to understand how to select a better fullerene-based acceptor for the high-performance SM-OSCs.