Organic-inorganic hybrid halide perovskites combine the optoelectronic properties commonly associated with high performance semiconductors with materials synthesis or processing routes involving very simple methods, including solution-based chemistry making them ideal materials for applications in solar cells . Since the first reported hybrid perovskite ( general formula ABX3) methylammonium lead iodide (MAPbI3), many variants have been synthesised, most employing a mixture of cations A+ = MA+/FA+/Cs+, Certified device efficiencies have risen to 22.1% in five years ( higher than commercial silicon based devices) and these "champion" systems contain a mixture of A-type cations.This experiment will determine the detailed structures of the "champion" materials contained within these high efficiency solar cells.