Synthesis and properties of non-fullerene acceptor materials containing aromatic heterocycle substitutions

Abstract

In recent years, organic solar cells (OSCs) have developed rapidly. Among the various active layer materials, non-fullerene acceptor materials exhibit a well-defined chemical structure, easily controllable energy levels and absorption, and a unique electron cloud distribution, making them a prominent research focus. Through molecular design, a series of acceptor–donor–acceptor (A–D–A) small molecule acceptor (SMA) materials have been developed. These materials, composed of an intermediate core, alkyl side chain groups, and terminal groups, possess more suitable absorption spectra and can effectively regulate the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of the acceptor material. This optimization enhances their energy level and absorption spectra alignment with the donor material and improves the photoelectric conversion efficiency. Notably, the introduction of aromatic heterocycles into the terminal groups represents an effective modification strategy. The incorporation of aromatic heterocycles can influence the electron cloud distribution of the terminal groups, exciton dissociation, and charge transport, leading to varying optoelectronic properties of non-fullerene small molecules. In this paper, we designed and synthesized two new SMA materials, BO-ICTTh and BO-ICTFr, by attaching thiophene and furan rings to the terminal groups of the acceptor materials through a Stille coupling reaction. We investigated the optical, electrochemical, and photovoltaic properties of these materials.