Lead halide perovskite materials have a huge potential in solar cell technology. They offer the combined advantages of low-cost preparation and high power-conversion efficiency. The present review focusses on the following topics: Power Conversion Efficiency; Electron Transport, Hole Transport and Interface Layers; Material Preparation; Cesium-Doped Lead-Halide Perovskites; Formamidinium-Doped Lead-Halide Perovskites; Methylammonium Lead-Halide...