This thesis presents the fundamental research and latest findings in the field of flexible/wearable photovoltaic technology. It comprehensively summarizes the rapid developments of flexible photovoltaics, from traditional planar to fiber solar cells. It also discusses the rational design of fiber solar cell materials, electrodes and devices, as well as critical factors such as cost, efficiency, flexibility and stability. Furthermore, it covers fundamental theoretical principles and novel fabrication technology as well as their potential applications. This book provides practical information for university researchers and graduate students interested in flexible fiber photovoltaics, and inspires them to design other novel flexible/wearable electronics and textiles.