Theoretical Design of L8-Core-Based Molecules by Stepwise Molecular Engineering of Non-Fullerene Acceptors

Abstract

L8-core, as the central core of L8-Ph, which is a promising A-DA′D-A type non-fullerene acceptor (NFA), has been reported for its excellent photoelectric properties, such as good fill factor and high power conversion efficiency. In order to further explore the photovoltaic performance of L8-core-based molecules, an efficient and useful stepwise molecular engineering strategy was adopted for molecular design. In this article, a series of acceptors were designed via this strategy, and density functional theory (DFT) and time-dependent density functional theory (TD-DFT) were used to calculate their geometrical structures, frontier molecular orbitals, absorption spectrum, and other important parameters. Significantly, among the newly designed molecules, L8Se-Ph and L8Se-Ph-4Cl demonstrate superior photovoltaic performance, with energy levels and light absorption spectra comparable to or surpassing those of L8-Ph. Although L10-Ph, L10Se-Ph, and L10Se-Ph-4Cl exhibit slightly inferior higher electron affinities and lower ionization potentials, they suggest that targeted modifications could enhance their photovoltaic properties, rendering them promising candidates for further optimization as photovoltaic materials.