Compact Capacitance Model for OTFTs at Low and Medium Frequencies

We present a compact capacitance model for organic thin-film transistors (OTFTs), which is valid not only in the accumulation regime but also in the partial and total depletion regimes. The parameters applied in the model are analytically extracted from the current-voltage characteristics of the devices, using a previously developed unified model and the parameter extraction method. The overlap capacitance effect is taken into account, and the frequency dependence is considered empirically by means of the insulator permittivity. Comparisons between modeled and experimental gate-to-channel capacitances of staggered upper contact p-channel OTFTs based on P3HT-PMMA and PCDTBT-PMMA show the validity of the model at low and medium frequencies.