High-Resolution In-Situ Synchrotron X-Ray Studies of Inorganic Perovskite CsPbBr : New Symmetry Assignments and Structural Phase Transitions.

Perovskite photovoltaic ABX systems are being studied due to their high energy-conversion efficiencies with current emphasis placed on pure inorganic systems. In this work, synchrotron single-crystal diffraction measurements combined with second harmonic generation measurements reveal the absence of inversion symmetry below room temperature in CsPbBr . Local structural analysis by pair distribution function and X-ray absorption fine structure methods are performed to ascertain the local ordering, atomic pair correlations, and phase evolution in a broad range of temperatures.