Numerical Modelling of Carrier Transport in Organic Field Effect Transistors

Organic field effect transistors (OFETs), used in the fabrication of nano-sensors, are one of the most promising devices in the field of organic electronics, because of their light weight, flexible and low fabrication cost. However, the optimization of such OFETs is still in an early stage due to the very limited analytical as well as numerical models presented in the literature. This research presses to demonstrate a numerical carrier transport model based on finite element method (FEM), to investigate the I-V characteristic of OFETs. Two various organic semiconductor materials have been included in the study, polyaniline and pentacene, where a micro-scale as well as a nano-scale models have been presented. OFETs have been studied in terms of channel length, dielectric thickness, and doping level impact. We nominated the threshold voltage, the on/off current ratio, the sub threshold swing, and the field effect mobility’s as the main output evaluating parameters. The numerical model has shown the criticality of the doping effect on tuning the device flowing drain current, to exceed 300 μA saturation current, along with threshold voltage of -0.1 V under a channel length of 30 nm. Additionally, the study highlights the effectiveness of the polyaniline over pentacene as nano-channel length OFET, due to the boosted conductivity of polyaniline with respect to pentacene.

Soft template assisted self-assembly: a general strategy toward two-dimensional molecular crystals for high-performance organic field-effect transistors

Two-dimensional molecular crystals (2DMCs) are highly desirable to probe the intrinsic properties in organic semiconductors and are promising candidates for constructing high-performance optoelectronic devices. Liquids such as water are favorable...

Computational studies on nitrogen (N)-substituted 2,6-diphenylanthracene: a novel precursor of organic field effect transistor materials

The investigation shows that nitrogen (N)-substituted π-conjugated semiconductor materials have improved optical and electronic performance and work efficiently in organic field-effect transistors (OFETs).

Temperature Sensors Based on Organic Field-Effect Transistors

The rapid growth of wearable electronics, Internet of Things, smart packaging, and advanced healthcare technologies demand a large number of flexible, thin, lightweight, and ultralow-cost sensors. The accurate and precise determination of temperature in a narrow range (~0–50 °C) around ambient temperatures and near-body temperatures is critical for most of these applications. Temperature sensors based on organic field-effect transistors (OFETs) have the advantages of low manufacturing cost, excellent mechanical flexibility, easy integration with other devices, low cross-sensitivity, and multi-stimuli detectability and, therefore, are very suitable for the above applications. This article provides a timely overview of research progress in the development of OFET-based temperature sensors. First, the working mechanism of OFETs, the fundamental theories of charge transport in organic semiconductors, and common types of OFET temperature sensors based on the sensing element are briefly introduced. Next, notable advances in the development of OFET temperature sensors using small-molecule and polymer semiconductors are discussed separately. Finally, the progress of OFET temperature sensors is summarized, and the challenges associated with OFET temperature sensors and the perspectives of research directions in this field are presented.

Effect of dielectric surface passivation on organic field-effect transistors: spectral analysis of the density of trap-states

The semiconductor/dielectric interface is arguably the most important region in field-effect transistors. This article investigates the performance-enhancing effects of passivation of the dielectric surface by a self-assembled layer (SAM) of silanes on organic field-effect transistors. Apart from conventional figures of merit for the devices, the energetic distribution of the density of the in-gap trap-states (trap-DOS) and the contact resistance are evaluated using numerical methods. The investigation reveals that the surface passivation of the dielectric SiO2 has a dual effect on device operation. Firstly, it establishes quantitatively that the surface passivation leads to a significant reduction in the density of both shallow and deep traps in the organic semiconductor PBTTT-C14. This effect outweighs the impact of the SAM dipoles on the device turn-on. Secondly, the contact resistance gets lowered by a factor of more than 10 due to the improved top-surface morphology of the PBTTT-C14 thin film. The lower contact resistance in devices is corroborated by lower contact potential difference between PBTTT-C14 and gold, measured using scanning kelvin probe microscopy.