Behavioral modeling for low-voltage pentacene-based OTFTs and their implementations for organic logic circuits

We present a behavioral compact model and its implementation for low-voltage pentacene-based organic thin film transistors (OTFTs) using industry standard BSIM4 (Berkeley Short-channel IGFET Model) in LTspice platform. First, we simplify the number of BSIM4 model parameters according to the device structure. On the other hand, we adapt the BSIM4 mobility equation to OTFT and also involve the off-current using two behavioral current sources. Then, we perform metaheuristics-based optimization to extract the related BSIM4 model parameters together with additional four parameters, introduced in this work, fitting the modified model to the experimental data of an OTFT, using pentacene active layer. Finally, we implement the behavioral compact model in LTspice and validate its usage for low-voltage pentacene-based OTFTs comparing the experimental and modeled current-voltage curves. In this study, we also successfully simulate OTFT implementations of a Pseudo-E inverter, a Pseudo-E NAND gate, and a 1-bit full adder circuit based on NAND gates using our behavioral OTFT model and then investigate the static and dynamic performance parameters of these circuits. The supply voltage is 3 V and maximum frequency of the inputs is 500 Hz in the simulations.(c) 2022 Karabuk University. Publishing services by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

This study presents a behavioral compact model and its implementation for low-voltage pentacene-based organic thin film transistors (OTFTs) using the industry standard BSIM4 model and LTspice platform. The model parameters are simplified according to the device structure, and the BSIM4 mobility equation is adapted for OTFTs. Metaheuristics-based optimization is performed to extract the model parameters and fit the modified model to experimental data. The behavioral compact model is implemented in LTspice and validated for low-voltage pentacene-based OTFTs. Additionally, OTFT implementations of a Pseudo-E inverter, a Pseudo-E NAND gate, and a 1-bit full adder circuit are successfully simulated using the behavioral model.