Fundamental Photophysics and Degradation Mechanisms in Perovskite Solar Cells

This Special Issue focuses on the fundamental physical mechanisms that govern performance and instability in perovskite solar cells, with particular emphasis on spectroscopic interrogation of charge dynamics and degradation processes. Contributions are invited that elucidate the microscopic origins of carrier generation, recombination, trapping, and ion migration in metal halide perovskites, and their coupling to structural, electronic, and interfacial disorder. Advanced spectroscopic techniques—including time-resolved optical spectroscopy, transient absorption, impedance spectroscopy, photoemission methods, and operando/in situ approaches—are encouraged to reveal dynamic processes across relevant time and length scales. Special attention will be given to defect energetics, polaron formation, phase instability, and the role of interfaces in governing non-radiative losses and long-term device evolution. Studies that establish quantitative relationships between spectroscopic observables and device-level degradation under electrical, thermal, and illumination stress are particularly welcome. By connecting fundamental photophysics with emergent instability pathways, this issue aims to deepen the mechanistic understanding required for rational design of stable perovskite photovoltaic systems.