Metal halide perovskites under compression
Within the last ten years, the power conversion efficiencies of metal halide perovskite (MHP) solar cells have developed at an unprecedented rate to above ∼24%. The outstanding photoresponse features of MHPs make them promising materials in the photovoltaic field, opening a new chapter for energy conversion from solar power to electricity. Recently, the unique tool of high pressure has been applied to MHPs to optimize their physical properties and obtain an in-depth understanding of their structure–property relationships. High pressure studies on MHPs allow for the in situ and continuous tailoring of MHP structures and properties, which is not feasible using traditional chemical methods. More importantly, the underlying transition and engineering mechanisms, which are hidden at ambient conditions, are successfully revealed through high pressure treatment. In this review, we aim to comprehensively summarize the structure and property engineering of MHPs in the high pressure dimension. Systematic comparisons between MHP systems are expected to reveal the structure/property contributions of different components in MHPs. Our discussions on high pressure MHPs are expected to offer some new strategies for the further design and synthesis of MHPs with promising applications.