Exploring the PT Phase Diagram*

Perovskite photovoltaic ABX₃ systems possess high energy-conversion efficiencies.  Understanding their atomic-level properties will lead to their optimization and utilization in real-world applications. Synchrotron-based structural measurements over a broad range of temperatures and pressures are being conducted.  The detailed studies have revealed new space group symmetries, which have revised the existing assignments. High-pressure measurements reveal multiple low-pressure phases, one of which exists as a metastable phase at ambient pressure. This work should help guide research in the perovskite photovoltaic community by providing the structural details needed to develop accurate theoretical models.