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 fieldeffect 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.