Regioregular polymerized small-molecule acceptors for high-performance all-polymer solar cells

Abstract

All-polymer solar cells (all-PSCs) have attracted increasing attention because of their distinctive features of superior morphological stability and mechanical durability. In recent years, all-PSCs have made rapid progress, thanks to the strategy of using polymerized small molecular acceptors (PSMAs). The isomerization of monomer of fused ring small molecule acceptors (SMAs) derived from the uncertain position of the bromine atoms on terminal groups leads to regiorandom PSMAs. This isomerization effect can significantly affect the absorption spectra, frontier molecular orbital energy level, crystallinity, mobility, and orientation of PSMAs. Integrating PSMAs with regioregularity endows the materials with better absorption coefficients, superior backbone ordering and optimal blend morphology compared to those of their regiorandom counterparts. Benefitting from these advantages, many regioregular PSMAs have been reported, and the PCE of binary single junction all-PSCs has exceeded 18%. In this review, the advances of regioregular PSMAs in the past three years for high-performance all-PSCs are summarized, and the guidelines for future structure design of PSMAs are discussed.