Self-Consistent Extraction of Mobility and Series Resistance: A Hierarchy of Models for Benchmarking Organic Thin-Film Transistors

Organic thin-film transistors (OTFTs) are usually benchmarked across different devices and technologies based on the threshold voltage, charge carrier mobility, and series resistance. However, conventional parameter extraction established for silicon transistors frequently lead to misleading results when applied to OTFTs. Some of the peculiarities of OTFTs can be addressed by the virtual-source (VS) emission–diffusion (ED) theory. Using published data and own measurements, we show that the electrical characteristics of OTFTs partially limited by mobile charge supply to the channel, thermic emission, or by velocity saturation can be successfully predicted by an organic VSED model. Simplifying the current-voltage dependence obtained from the VSED theory modified for organic materials (OVSED), we introduce a hierarchy of benchmark models only employing one additional parameter with a specific electrical signature for each of these limitations. As a special case, the hierarchy includes the widely applied Shichman–Hodges (SH) model. In combination with standard nonlinear least-squares solvers, such benchmark models can replace conventional extraction methods and are applicable to a wider range of OTFT technologies.