Disentangling the Phase Diagram of MAPbBr3 at Pressure

Metal halide perovskites have emerged as a class of promising semiconductors for high-performance optoelectronics devices. However, a clear understanding of the relationship between their physical structures and electronic properties is still missing due to the limitation of as-synthesised perovskites and the Goldschmidt tolerance factor. Especially, limited studies have been conducted on perovskites with organic cations under pressure and there is still much controversy. We propose to perform a large volume neutron diffraction experiment at high pressure looking at the structural transformation sequence of MAPbBr3 in a variety of pressure transmitting media. This will not only disentangle the issue of the pressure transmitting media on the phase diagram but also provide a unique set of crystallographic information in each of the phases observed upon compression which only the use of neutron diffraction can provide.