Graphene has many unique properties that have generated tremendous excitement in the scientific community and make graphene appropriate for many applications. The tuning of graphene’s Fermi level by modulation of charge carriers in graphene is an important factor in determining the successful operation of electronic/optoelectronic devices. This book focuses on different methods of performing carrier modulation in graphene and the application of this doped graphene in diodes, field effect transistors, solar cells, transparent conducting electrodes, and supercapcitors. The book gives an overview of the current status of the research and development in graphene and will be helpful for scientists, researchers, engineers, students, and readers who want to know about graphene and its applications and also other 2D nanomaterials.