Visualizing and Suppressing Nonradiative Losses in High Open-Circuit Voltage n-i-p-Type CsPbI <sub/>3</sub> Perovskite Solar Cells

摘要： Since their first demonstration in PV devices in 2009, organic-inorganic hybrid metal halide perovskites have attracted tremendous attention because of their potential applications in solution-processed photovoltaics (PV). Many research efforts, such as composition engineering and interface engineering, have been dedicated to enhancing the power conversion efficiency (PCE) of perovskite-based solar cells (PSCs) to a high level of over 24%. However, operational stability issues remain a major challenge for organic-inorganic hybrid perovskites on the way towards commercialization. Alternatively, all-inorganic perovskites (CsPbX3, X = Cl, Br, I), have received increasing interest because they are theoretically stable up to their melting points (>300 °C). Especially, CsPbI3 in the cubic phase stands out because of the lowest bandgap (of ~1.75 eV) among the all-inorganic lead-based perovskites. Compared to all other all-inorganic lead-based perovskite halide semiconductors materials which have bandgaps higher than 1.90 eV, the 1.75 eV bandgap CsPbI3 is able to absorb slightly more light in the visible region and nominally is an excellent candidate for the front cell in tandem architectures with silicon as the back cell.