Textbook in PDF format Organic–inorganic hybrid metal halide perovskite materials have attracted significant attention due to their advantages of low cost, tunable band gap, solution processing, high molar extinction coefficient, low exciton binding energy, and high carrier mobility. Perovskite absorber layers play a decisive role in the realization of high-power conversion efficiency in perovskite solar cells (PSCs). This book systematically and comprehensively discusses device structures, working principles, and optimization strategies of perovskite absorber layers for PSCs to help foster commercialization of these environmentally friendly power sources. It describes strategies to optimize the quality of perovskite films, including composition engineering, dimensional engineering, solvent engineering, strain engineering, additive engineering, and interface engineering