Multifunctional polymers in perovskite photovoltaics: bridging efficiency, stability, and manufacturing

Abstract

Polymers have emerged as multifunctional enablers in the evolving architecture of perovskite solar cells (PSCs), addressing key challenges in film formation, interface engineering, defect modification, and device longevity. Their molecular tunability, macromolecular chains, and compatibility with low-temperature solution processing make them ideal candidates for integration at various functional layers within PSCs. This review delineates the strategic roles of polymers as both passive and active components in PSCs and emphasizes their indispensable contribution toward scalable, printable perovskite photovoltaics. In the active layer, polymeric additives modulate the nucleation and crystal growth kinetics of the perovskite phase, leading to adjusted grain size, reduced trap states, and suppressed ion migration. At the interfaces, conjugated polymers serve as efficient charge-transport materials (CTMs), offering favorable energy level alignment and improved mechanical adhesion, while insulating polymers mitigate interface-induced recombination and phase instability. Additionally, polymers have been pivotal in enabling flexible and lightweight PSCs. This review provides a comprehensive overview of perovskite defects and systematically investigates the role of polymers in enhancing the properties of PSCs. We explore the incorporation of polymers into the active layer, charge transport layers (CTLs), and their interfaces, highlighting recent advancements in self-healing, deep-level trap passivation, network formation, the use of hyperbranched polymers for flexible devices, and so on. A detailed analysis of semiconducting polymers, focusing on main-chain and side-chain structures, physical properties, and dopant-free systems, is presented for both the active layer as the bulk heterointerface and CTLs. Finally, addressing the imminent industrialization of PSCs, we examine various printing techniques and propose polymer-based strategies to mitigate structural defects during large-scale fabrication, concluding with a perspective on future scalability.