Abstract
Polymer dielectrics in organic field‐effect transistors (OFETs) are essential to provide the devices with overall flexibility, stretchability, and printability and simultaneously introduce charge interaction on the interface with organic semiconductors (OSCs). The interfacial effect between various polymer dielectrics and OSCs significantly and intricately influences device performance. However, understanding of this effect is limited because the interface is buried and the interfacial charge interaction is difficult to stimulate and characterize. Here, this challenge is overcome by utilizing illumination to stimulate the interfacial effect in various OFETs and to characterize the responses of the effect by measuring photoinduced changes of the OFETs performances. This systemic investigation reveals the mechanism of the intricate interfacial effect in detail, and mathematically explains how the photosensitive OFETs characteristics are determined by parameters including polar group of the polymer dielectric and the OSC side chain. By utilizing this mechanism, performance of organic electronics can be precisely controlled and optimized. OFETs with strong interfacial effect can also show a signal additivity caused by repeated light pulses, which is applicable for photostimulated synapse emulator. Therefore, this work enlightens a detailed understanding on the interface effect and provides novel strategies for optimizing OFET photosensory performances.
Highlights
Previous efforts have been made to study the “hidden” interfa cial effect
We found that the photosensitive organic field-effect transistors (OFETs) characteristics, including drain–source current (IDS), μ, and Vth, were significantly affected by polar group of the poly mer dielectrics and the OSC side chain
OFETs with strong interfacial effect show an excitatory postsynaptic current (EPSC)-like photore sponse behavior, such as long term of current recovery when the light exposing on the devices is turned off, and photocurrent additivity caused by repeated light pulses
Summary
Previous efforts have been made to study the “hidden” interfa cial effect. For example, Scanning Kelvin probe microscopy was Flexible and stretchable organic field-effect transistors (OFETs) employed to directly observe the charge protein on the interfaces have attracted intensive research and commercial interests since in lateral organic transistors.[17,18,19] OFETs with OSC single crysthey are applicable in wearable devices, biomedical electronics, tals and a parylene dielectric were used to study photoinand various sensors.[1,2,3,4] Polymer dielectrics are essential for pro duced charge transfer across the interface.[20,21] Several profiles viding these devices with overall flexibility, stretchability, print of the interfacial effect were revealed based on these investigaability, and in some cases biocompatibility.[1,4,5,6,7] Microstructural tions, primarily including: (a) shallow trap of charge carriers in OSC by the weak intermolecular interaction from the dielec. OFETs with strong interfacial effect show an excitatory postsynaptic current (EPSC)-like photore sponse behavior, such as long term of current recovery when the light exposing on the devices is turned off, and photocurrent additivity caused by repeated light pulses. These features make the OFETs applicable for photostimulated synapse emulator, which is promising for brain-inspired electronics and human– machine interface, etc.,[8] various photosensors with control lable performances were obtained by utilizing this mecha nism. We provide novel strategies to fabricate synapse-emulating OFETs and photosensors with controllable performances
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