Semiconductor/dielectric interface in organic field-effect transistors: charge transport, interfacial effects, and perspectives with 2D molecular crystals

Abstract

Organic field-effect transistors (OFETs) have been the hotspot in information science for many years as the most fundamental building blocks for state-of-the-art organic electronics. During the field-effect modulation of the semiconducting channel, the gate dielectric always has a significant influence on the charge transport behaviours. Hence, understanding of the nature of charge carriers at the semiconductor/dielectric interface and realizing functional OFETs with superior performance have been the cornerstones for the sustainable advancement in organic electronics. With the joint efforts of predecessors, various basic theories and models have been advanced to describe the charge transport processes in organic crystals. To make a further breakthrough, more accurate correlation between the electrostatic properties of dielectrics and charge carrier behaviours is urgently needed. The high-quality interface-like films, without nonideal factors, two-dimensional molecular crystals (2DMCs), have been spotted as a powerful platform for direct and accurate characterization of the intrinsic charge transport behaviours at the semiconductor/dielectric interface. In this article, the recent breakthroughs in the physics of charge transport, interfacial effects, and perspectives with 2DMCs in OFETs are reviewed, providing great benefits to penetrate the fundamental studies and keep up with the revolutionary advancement in organic-electronics road map.

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“…Device characteristics under dry nitrogen show threshold voltage of −1.32 ± 0.77 V and device on-off ratios on the order of 10 3 (1247 ± 1556 V). Charge mobilities were calculated to be 1.34 ± 0.92 cm 2 V −1 s −1 at a gate voltage of −5 V, which is on the same order as other reported organic and carbon-based back gated transistors that range from 0.37 to 30 cm 2 V −1 s −1 ( Pei et al, 2020 ; Shiomi et al, 2019 ; Snow et al, 2005 ).

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Synergistic Effect of Solvent Vapor Annealing and Chemical Doping for Achieving High-Performance Organic Field-Effect Transistors with Ideal Electrical Characteristics

“…Whereas structural defects in the film are common sources of charge trapping, charge trapping sites are also typically found at the device interfaces, which are related to a large variety of effects (chemical impurities, local morphology and structure variations, energetic disorder, etc. ). − Although clarifying the sources of traps is a complex matter, the device improvements observed and rationalized in this work by the different treatments provide a better understanding of prevailing charge trapping mechanisms. We have observed that the vapor annealing of the films employing a polar solvent in which the OSC is not very soluble has given rise to a reduction of the shallow charge traps.…”

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“…where T 0 = 8.5 × 10 3 K. (Figure 3b). [39] We like to point out, that for the temperature range between 350 K to 20 K, a poor fit was found for ln( )…”