Emerging photovoltaic technologies such as organic/hybrid solar cells have been gaining increasing attention, and they are on the step of being commercialized. Hybrid solar cells consist of colloidal quantum dots and conjugated polymers have the potential to perform better while retaining the features of e.g. cost-efficient, thin, and flexible. This book begins with a brief introduction to the state-of-the-art hybrid solar cells. Critical factors limiting the device performance are highlighted and strategies for further improvement are demonstrated by giving recent examples from literature. In addition, research results from the author's PhD work are presented. Both material and device structure, from quantum dots synthesis and modification towards device fabrication, were investigated systematically, leading to outstanding hybrid solar cell performance.