This book presents the principle of operation, materials used and possible applications of third generation solar cells that are under investigation and have been not commercialized on a large scale yet. The third generation photovoltaic devices include promising emerging technologies such as: organic, dye sensitized, perovskite and quantum dot sensitized photocells. This book introduces the reader to the basics of third generation photovoltaics and presents in an accessible way phenomena and a diversity of materials used. In this book one will find the description of the working principle of new promising solar technologies, their advantages and disadvantages, prospect applications and preliminary analysis of their impact on the environment. The fundamentals of traditional solar cell operation are also included in the book facilitating understanding of new ideas. This book is ideal reading for everyone who is interested in novel solutions in photovoltaics as well as applications of nanotechnology, photochemistry and materials research.