Semitransparent Quasi-2D Dion–Jacobson Layered Perovskite Films for Indoor Photovoltaics

Semitransparent indoor photovoltaics (IPVs) based on layered perovskites offer opportunities for integrated energy harvesting, yet their structural understanding and implementation remain limited. Here, we report the first demonstration of semitransparent thin-film photovoltaic operation using a quasi-2D Dion–Jacobson (DJ) perovskite absorber (n = 5). Owing to the absence of crystallographic information for this phase, density functional theory (DFT) calculations were employed to establish a structural model, which was used to interpret experimental observations. The optimized structure exhibits a layered framework with a slight octahedral tilt and a wide bandgap with nearly direct band-edge characteristics. Experimental results reveal that precursor concentration critically governs crystallization behavior, lattice strain, and film morphology. An optimal condition yields a continuous, low-strain film with favorable semitransparent characteristics and enables corresponding device operation under indoor illumination. These findings highlight the importance of crystallization control in DJ perovskites and provide a framework for designing semitransparent quasi-2D absorbers for IPV applications.