This book consists of six chapters: In the first chapter, electrical and material properties and charge transport in organic and graphene based FETs are introduced. In the second chapter, device architectures of amorphous copolymer FETs are discussed. The combination of recessed electrodes and surface treatments on electrical contact is investigated. In the third chapter, device physics and charge transport of donor-acceptor copolymer based FETs are discussed. Charge transport measurements in steady-state and under non-quasi-static conditions reveal device physics in dual-gate configuration. In the fourth chapter, device characteristics of ambipolar copolymer based FETs are focused. Those possess balanced electron and hole mobilities which are both > 0.5 cm2/V-s. The trap DOS is calculated using two analytical methods. In the fifth chapter, charge transport in copolymer based FETs employing 4-point-probe configuration is studied. Such polymer FETs possess the mobilities of up to 3 cm2/V-s. In the sixth chapter, transformation of electrical characteristics of graphene FETs with an interacting capping layer of fluoropolymers and pi-conjugated organic semiconductors is investigated.