An Analytic Current–Voltage Equation for Top-Contact Organic Thin Film Transistors Including the Effects of Variable Series Resistance

Abstract

An analytic current–voltage (I–V) equation for top-contact organic thin film transistors (OTFTs) is derived by analyzing the channel and the overlap region separately. From the analysis on the overlap region, the series resistance of OTFTs is found to be a function of the gate voltage due to the sheet resistance change of the accumulation layer. Using the derived I–V equation, the characteristics of both the channel and the overlap region are well-explained. The I–V equation is verified with fabricated top-contact OTFTs and metal–insulator–semiconductor (MIS) capacitors, and the predicted I–V characteristics from the equation agree well with the measurements. Also, the ratio of the series resistance to the total resistance of the device is up to 60% which shows significant influence of the series resistance on top-contact OTFT performance.