There has been considerable excitement concerning some of the recent breakthroughs and theoretical promise that has been afforded to photovoltaics solar cells through the use of new nanomaterials and nanostructured devices. This book attempts to provide the fundamental framework upon which these developments have been based. The book begins with a general introduction to photovoltaics; but unlike other solar cell books, this is done with a focus on the fundamental physical limits and practicality of assumptions which form the basis for the ensuing discussion of nanostructured approaches to photovoltaics conversion. The discussion of the approaches is presented based upon basic quantum mechanics to provide a framework that is not merely a topical treatment of recent results, but also a reference which should prove useful for future developments.