Rational and green functionalization of B,N-C60 by DNA bases devised as incredible electron transport compounds for perovskite photovoltaic devices

Abstract

Environmentally benign materials were devised to be employed as excellent electron transporting layers (ETLs) in perovskite solar cell (PSC) devices. They were based on B,N-C60 fullerene functionalized with a pyrrolidine ring (fulleropyrrolidine) attached to a thiophene ring and a cyanoethyl group (named F-B,N-C60), which was further functionalized by four deoxyribonucleic acid (DNA) bases from their exocyclic N (in NH/NH2 groups) or endocyclic N atoms. To investigate electronic, optical, structural, and electron mobility characteristics of such compounds, density functional theory (DFT) calculations were done. Lowest unoccupied molecular orbital (LUMO) levels of all ETL samples were deeper than conduction band of perovskite CsFAMAPbIBr in PSCs (except for the two samples F-B,N-C60-G1 and F-B,N-C60-G2) that simply injected electrons from CsFAMAPbIBr toward Ag electrode. Highly extraordinary electron mobilities achieved for B,N-C60 functionalized fullerenes were changed from 5.1245 to 106.2272 cm2V−1s−1 that were about 1016-1018 times larger compared to that of B,N-C60 (3.1844×10−16 cm2V−1s−1). Among all ELs, the two samples F-B,N-C60-G1 and F-B,N-C60-G2 displayed very much larger photovoltaic parameters than the rest of B,N-C60 functionalized ETLs. High fill factor (FF), power conversion efficiency (PCE), and open circuit voltage (VOC) values were measured for the PSCs with the devised ETLs in ranges of 0.795–0.893, 8.4522–22.887%, and 0.468–1.129 V, respectively, establishing they could be applied as remarkable ETL materials for photovoltaics.