The production of electricity from sunlight using photovoltaic devices is one of the most promising technologies for meeting future energy requirements. CH3NH3PbI3 was first reported in a solar cell in 2009 (with an efficiency of 3.81%) and since then the efficiencies of the CH3NH3PbI3 solar cells have increased extremely rapidly to 20.1%. Our current synthetic work involves exploring diamine doping in CH3NH3PbI3 and we have found a new compound, H3NC2H4NH3PbI4. Our laboratory single crystal XRD data is dominated by the strong scattering of Pb and I, making accurate determination of the organic cation difficult. We propose to carry out a single crystal neutron diffraction study to gain an accurate structural model of H3NC2H4NH3PbI4, particularly with respect to the H3NC2H4NH32+ cation and to correlate this model with the properties H3NC2H4NH3PbI4 displays.