Field-Effect Mobility of Organic Polymer Thin-Film Transistors

We present a method of extracting the field-effect mobility from the transfer characteristics of organic polymer thin-film transistors (OP-TFTs), in both the linear and saturation regimes, by accounting for the dependence of the mobility on the gate bias, which translates to a dependence on the accumulated density of majority charge carriers in the channel. This method is compared to the commonly used extraction methods, which are based on the standard MOSFET square-law drain current equations that do not account for the variation of mobility with the applied gate bias. We show that by using the standard MOSFET equations, the extracted field-effect mobility can be significantly overestimated. We also demonstrate the use of the proposed method to extract the field-effect mobility at different measurement temperatures and present the dependence of the extracted parameters on temperature.