Recent Advances in PSMA-Type Polymer Acceptors for All-Polymer Solar Cells

Abstract

All-polymer solar cells (all-PSCs) offer intrinsic advantages in mechanical flexibility, film toughness, and morphological stability, making them promising candidates for flexible and scalable organic photovoltaics. Polymerized small-molecule acceptors (PSMAs) inherit the broad spectral absorption and tunable electronic structures of high-performance small-molecule acceptors, effectively overcoming the insufficient near-infrared absorption of conventional polymer acceptors and driving the power conversion efficiencies of all-PSCs into the 17–19% range. However, once high-performance PSMAs provide suitable absorption and energy levels, further improvements can no longer be achieved by independently optimizing a single intrinsic parameter, such as optical absorption, energy-level alignment, or charge-carrier mobility. Instead, polymer-chain entanglement, molecular and energetic disorder, suboptimal donor–acceptor matching, and the difficulty in simultaneously controlling crystallization, phase separation, and vertical composition distribution have become the major barriers to further efficiency gains. Recent efficiencies exceeding 20% demonstrate that high-performance all-PSCs rely on the concerted optimization of PSMA molecular structures, donor–acceptor interactions, active-layer morphology, and processing kinetics. This review, therefore, focuses on comparing the strategies that have enabled breakthroughs beyond 20% efficiency. On this basis, the remaining challenges associated with long-term stability, green-solvent processing, batch-to-batch consistency, and scalable manufacturing are further discussed, and the common mechanisms underlying the crossing of the 20% efficiency threshold, together with future development directions, are summarized.