2D expanded conjugated polymers with non-fullerene acceptors for efficient polymer solar cells

Abstract

Non-fullerene polymer solar cells (PSCs) have attracted great attention due to their good optical absorption and convenient structure modification. Some small molecular acceptors such as ITIC have exhibited excellent photovoltaic performance. Based on these acceptors, it is very important to screen donor materials to further improve the performance. The benzotriazole-based polymer is an important type of donor material, especially for non-fullerene PSCs. We have designed and synthesized a type of benzotriazole-based conjugated polymer with a 2D expanded side chain. These polymers exhibit good crystallinity in films. Non-fullerene PSC devices based on polymer:ITIC show a PCE of 8.03% with a high J_SC of over 17 mA cm⁻², which might be attributed to its good crystallinity. This result indicates the advancement of the 2D extended structure in the design of a high performance polymer.