This book provides a comprehensive review of lead-free halide perovskites and explores their potential to revolutionize solar energy conversion. From elucidating the fundamental principles of solar energy conversion to exploring innovative techniques such as chirality enhancement, vapor deposition, and operando characterization, this book offers a thorough and authoritative overview of the field. Divided into three parts, the book begins with an introduction to the general properties of solar energy conversion mediated by lead-free halide perovskites. The second part of the book presents the latest developments and challenges of lead-free perovskite solar cells, and the book concludes with a section covering the current status and future trends of photocatalysis mediated by lead-free perovskites. In this book, readers will discover eco-friendly alternatives to traditional tin-based solar cells, and learn about the promise of green hydrogen production, and the synthesis of value-added chemicals using perovskite-based systems. With its breadth of coverage, this book is essential reading for researchers, engineers, and industry professionals seeking inspiration and valuable guidance to implement sustainable energy solutions using lead-free perovskite-based systems.