This book presents the fundamental aspects of various energy resources, namely, photovoltaic energy, thermoelectric energy, green hydrogen generation, lithium-ion battery, fuel cell, supercapacitors along with various devices and applications. The primary focus of the chapters is to explore utilization of various materials like conventional bulk materials, thin films, low dimensional materials, nanomaterials, quantum materials, for above-mentioned energy generation process. The various physical and chemical routes for the synthesis of these energy materials are also discussed in the various chapters. Students from diverse backgrounds in engineering and physical sciences may find it as text for a graduate level course on this subject, while practicing engineers may find this book as a useful reference.