Recent advances of polymer acceptors for efficient all-polymer solar cells

Abstract

All-polymer solar cells (all-PSCs) featuring a photo-active layer composed of a blend of p-type polymers as donors and n-type polymers as acceptors show superior operational stability and remarkable mechanical flexibility compared to conventional organic solar cells with n-type small molecules as acceptors. Although recent achievements have boosted the power conversion efficiencies of all-PSCs beyond 19%, further progress has been hampered by the lack of electron-deficient building blocks with optimized physicochemical properties and the slow evolution of polymer acceptors within the active layers. This review presents a comprehensive overview of the recent development of high-performing n-type polymer acceptors, systematically categorized into imide-functionalized polymers, amide-functionalized polymers, cyano-functionalized polymers, B ← N-embedded polymers, and polymerized small-molecule acceptors. Through a comprehensive analysis of structure–property–performance correlations, we illustrate the molecular design strategies that have proven effective in enhancing light absorption, charge mobility, and phase compatibility within donor–acceptor polymer networks. The review also identifies key challenges—such as reducing synthetic complexity, maintaining morphological stability, and minimizing energetic disorder—that must be addressed to fully realize the potential of all-PSCs. Ultimately, advancing the molecular engineering of polymer acceptors is pivotal for pushing the boundaries of efficiency, scalability, and long-term durability in all-PSCs.