Book excerpt: 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 Perovskites; Hysteresis, Stability and Toxicity Problems. The book references 334 original resources and includes their direct web link for in-depth reading. Keywords: Solar Cells, Lead Halide Perovskite Materials, Cesium-Doped Lead-Halide Perovskites, Formamidinium-Doped Lead-Halide Perovskites, Methylammonium Lead-Halide Perovskites, Electron-Transport Layer, Hole-Transport Layer, Interface Layers, Hysteresis Problem, Stability Problem, Toxicity Problem.