Current versus gate voltage hysteresis in organic field effect transistors

Research into organic field effect transistors (OFETs) has made significant advances-both scientifically and technologically-during the last decade, and the first products will soon enter the market. Printed electronic circuits using organic resistors, diodes and transistors may become cheap alternatives to silicon-based systems, especially in large-area applications. A key parameter for device operation, besides long term stability, is the reproducibility of the current-voltage behavior, which may be affected by hysteresis phenomena. Hysteresis effects are often observed in organic transistors during sweeps of the gate voltage (VGS). This hysteresis can originate in various ways, but comparative scientific investigations are rare and a comprehensive picture of "hysteresis phenomena'' in OFETs is still missing. This review provides an overview of the physical effects that cause hysteresis and discusses the importance of such effects in OFETs in a comparative manner.