CsPbI₃ quantum dots for photovoltaic applications: Structure, physics, and device-level strategies for enhanced performance

Perovskite quantum dots (PQDs) merge the advantages of traditional quantum dots—such as quantum confinement effects—with the intrinsic benefits of perovskite materials, including high defect tolerance and long exciton lifetimes. These combined properties make PQDs highly promising for next-generation photovoltaics, particularly as light-absorbing materials in solar cells. Although PQD-based solar cells (PQDSCs) have reached a certified power conversion efficiency (PCE) of 18.1 % within a decade, they still trail behind their silicon and bulk perovskite counterparts. This review critically explores the challenges and opportunities associated with PQDs, beginning with their fundamental structure, crystal chemistry, and key parameters—such as Goldschmidt's tolerance and octahedral factors—that influence phase stability. It also examines the mechanisms of defect tolerance, multiple exciton generation (MEG), and photoluminescence behavior. A comprehensive overview of PQD synthesis methods—including hot injection, ligand-assisted reprecipitation, and emulsion techniques—is provided, highlighting their impact on material quality. To address issues such as phase instability, surface defects, and insulating ligands, strategies like ligand engineering, post-synthetic treatments, and doping are discussed. Additionally, the review evaluates device-level approaches, including architectural optimization and charge transport layer engineering, aimed at improving the efficiency and long-term stability of CsPbI₃-based PQD solar cells.