Fluorinated Asymmetric 2D Core-Extended Nonfullerene Acceptors for Efficient Organic Solar Cells

Organic solar cell efficiency can be boosted through the strategic extension of the 2D conjugated core in nonfullerene acceptors (NFAs). In this work, two NFAs, IC-IQ2FDMBO-IC and IC2F-IQ2FDMBO-IC2F, were synthesized based on an asymmetric, fluorinated 2D-extended quinoxaline core featuring an unexpected N,N -dimethylmethanamine substitution. Compared to IC-IQ2FDMBO-IC, IC2F-IQ2FDMBO-IC2F exhibits deeper-lying energy levels and absorption extending to longer wavelengths due to its fluorinated terminal groups. When blended with PBDB-T, IC2F-IQ2FDMBO-IC2F forms more ordered and clearer fibril-like morphologies, resulting in an improved balance of charge carrier mobilities. Consequently, PBDB-T:IC2F-IQ2FDMBO-IC2F devices achieve a higher efficiency of 14.56%, surpassing devices based on PBDB-T:IC-IQ2FDMBO-IC. These results suggest that incorporating a fluorinated, asymmetric quinoxaline core is a rational design strategy for efficient NFAs.