Role and Contribution of Polymeric Additives in Perovskite Solar Cells: Crystal Growth Templates and Grain Boundary Passivators

Polymers or polymeric materials are used as additives for promoting the nucleation and crystallization of perovskite films to increase the crystal grain size. Due to their high molecular weight, polymers remain within perovskite‐crystal grain boundaries (GBs), where they passivate trap sites. Furthermore, some polymers function as charge‐transport materials in interfacial layers to effectively separate charge carriers and reduce charge recombination. Certain hydrophobic polymers protect perovskite films against moisture, whereas elastic polymers contribute to the mechanical resilience of perovskite films by crosslinking and self‐healing. Although polymeric additives have become essential to perovskite fabrication, a thorough review has not summarized their application to perovskite solar cells. Therefore, various strategies are comprehensively discussed for incorporating typical polymers and 1D polymeric materials into perovskite materials to improve the efficiency and stability of perovskite devices. Herein, thermoplastic, hydrophilic, and conductive polymers and elastomers are focused and related works are chronologically discussed to clearly elucidate the advances in perovskite devices.