Generic Parameter Extraction of Inkjet-Printed OTFTs via Optimisation Using LTspice and MATLAB

Parameter extraction for organic thin film transistors (OTFTs) is often performed using the MOSFET square-law to model current-voltage (IV) characteristics. Usually the IV characteristics at a single drain voltage bias is used for fitting the mobility and extrapolating the threshold voltage. Described herein is a method of parameter extraction which fits a family of curves to any given model, and is not limited only to the square-law. Using LTspice, a freely available circuit simulation tool, coupled with MATLAB, a routine has been prepared which performs parameter extraction for OTFT measurement results across a family of curves via optimisation. The use of a circuit simulator allows a wide array of models to be used, and modified, to achieve more accurate circuit simulation performance and possibly provide insight into device behaviour.