Progress in research on organic photovoltaic acceptor materials.

In the past two decades, organic solar cells (OSCs) have begun to attract attention as the efficiency of inorganic solar cells gradually approaches the theoretical limit. In the early development stage of OSCs, p-type conjugated polymers and n-type fullerene derivatives were the most commonly used electron donors and acceptors. However, with further research, the shortcomings of fullerene materials have become increasingly apparent.

Bromination and increasing the molecular conjugation length of the non-fullerene small-molecule acceptor based on benzotriazole for efficient organic photovoltaics.

Two novel non-fullerene acceptors, namely BZIC-2Br and Y9-2Br, were synthesized by employing a ladder-type electron-deficient-based fused ring central with a benzotriazole core. Y9-2Br is obtained by extending the conjugate length of BZIC-2Br. Compared with BZIC-2Br, Y9-2Br possesses a lower optical bandgap of 1.