‘The drive for us was looking for something to replace the lead that we can still get photovoltaic performance out of,’ she explains. They tested the lead-free perovskite, methylammonium tin triiodide (CH3NH3SnX3) as their photoactive material. Due to the instability of CH3NH3SnX3 when exposed to oxygen and moisture, all material and device processing was conducted in a nitrogen-filled glovebox. Equimolar quantities of SnI2 and CH3NH3I were dissolved in degassed N-dimethylformamide, with the solution then spin-coated onto a substrate.