Printing Semiconductor–Insulator Polymer Bilayers for High‐Performance Coplanar Field‐Effect Transistors

Abstract

Source-semiconductor-drain coplanar transistors with an organic semiconductor layer located within the same plane of source/drain electrodes are attractive for next-generation electronics, because they could be used to reduce material consumption, minimize parasitic leakage current, avoid cross-talk among different devices, and simplify the fabrication process of circuits. Here, a one-step, drop-casting-like printing method to realize a coplanar transistor using a model semiconductor/insulator [poly(3-hexylthiophene) (P3HT)/polystyrene (PS)] blend is developed. By manipulating the solution dewetting dynamics on the metal electrode and SiO dielectric, the solution within the channel region is selectively confined, and thus make the top surface of source/drain electrodes completely free of polymers. Subsequently, during solvent evaporation, vertical phase separation between P3HT and PS leads to a semiconductor-insulator bilayer structure, contributing to an improved transistor performance. Moreover, this coplanar transistor with semiconductor-insulator bilayer structure is an ideal system for injecting charges into the insulator via gate-stress, and the thus-formed PS electret layer acts as a "nonuniform floating gate" to tune the threshold voltage and effective mobility of the transistors. Effective field-effect mobility higher than 1 cm V s with an on/off ratio > 10 is realized, and the performances are comparable to those of commercial amorphous silicon transistors. This coplanar transistor simplifies the fabrication process of corresponding circuits.

Vertical‐Resolved Composition and Aggregation Gradient of Conjugated‐Polymer@Insulator‐Matrix for Transistors and Memory

“…P‐type OFETs with PS dielectrics exhibiting excellent stability under positive gate‐bias stress have been reported previously, [ 66,67 ] unless an elevated temperature is used to inject electrons into PS layer. [ 36,39,43 ]…”

Precise Control of Interfacial Charge Transport for Building Functional Optoelectronic Devices

“…Furthermore, appropriate hydroxyl‐free polymers, such as a divinyl‐tetramethylsiloxane‐bis(benzocyclobutene) derivative, can also be used as surface modifiers on SiO 2 dielectrics to achieve better n‐type charge‐transport behaviors in conjugated polymers . In fact, polymer coating has been demonstrated as a powerful method to modify the dielectric surface and improve the performance of OFETs . For example, Kim et al reported that the performance of pentacene FETs with a bottom‐gate top‐contact (BGTC) configuration could be modulated by changing the surface conditions of a polymer dielectric with different molecular structures due to their influence on the grain size/crystallinity of pentacene films.…”

Zwitterions for Organic/Perovskite Solar Cells, Light‐Emitting Devices, and Lithium Ion Batteries: Recent Progress and Perspectives

“…It is well known that the ability to transport the charge carriers between the electrodes and organic layers is very crucial to obtain highly efficient electronic devices . A mismatch between the energy levels of organic layers and inorganic electrodes leads to the generation of an energy barrier that hampers the extraction or injection of charge carriers .…”

“…[12][13][14] Recently, a significant attention has been paid to the use of zwitterions owing to their solubility in polar solvents for solution processing, [15][16][17] and dipole formation for the transfer of carriers [18][19][20] and ions. [24] A mismatch between the energy levels of organic layers and inorganic electrodes leads to the generation of an energy barrier that hampers the extraction or injection of charge carriers. The presence of both negative and positive ions in the same molecule enables zwitterions to develop interfacial dipole.…”

“…[24] A mismatch between the energy levels of organic layers and inorganic electrodes leads to the generation of an energy barrier that hampers the extraction or injection of charge carriers. [24] A mismatch between the energy levels of organic layers and inorganic electrodes leads to the generation of an energy barrier that hampers the extraction or injection of charge carriers.…”