The technology for organic thin film transistors (OTFTs) is suitable for large area electronics, disposable electronics and "Internet of Things" applications. Circuits employing OTFTs can be realized by using very cheap printing technologies. The electrical behavior of these devices is essentially different from the behavior of silicon MOSFETs and, in order to enable circuit design, compact models specific for OTFTs are needed.
The presented technology is an electrical compact model for OTFTs that:
(a) rely on microscopic charge and mobility models specifically tailored for organic semiconductors;
(b) reproduce the large-signal regime and non-quasi-static effects that are very likely to occur in organic TFTs;
(c) account for the presence of parasitic regions, outside the channel area, that are very likely to be present in devices obtained by printing processes with large alignment tolerances.
The model can be used as an “add-on” in most of the software packages for circuit simulation (SmartSpice, Spectre, ELDO, …)
All these features makes this model particularly well suited for the simulation of OTFTs realized by printing process.
Nowadays, investigations of the electrical behavior of OTFTs have mainly focused on modeling of the DC regime, while reproduction of AC operation has received less attention with most of the efforts devoted to the modeling of the quasi-static regime. However, it is well established that the order of magnitude of the cut off frequencies of OTFTs is in the range of few kilohertz and it is very likely that, in real applications, organic circuits must operate at frequencies driving the devices in a non quasi static (NQS) regime.
Being specifically designed for NQS regime, the proposed model provide a more accurate design in dynamic operation.
Benefits:
- The compact model is able to reproduce the static as well the dynamic behavior of OTFTs.
- It is implemented in the Verilog-A programming language, so it can be used in most of the commercial electronic design automation (EDA) tools.
- The accuracy of the computation can be increased (at the expense of computation speed).
- The compact model is easily adaptable to complex printing layouts, that could include parasitic (floating) regions not bounded by electrodes.