Enhanced Optical Switching Characteristics of Organic Phototransistor by Adopting Photo-Responsive Polymer in Hybrid Gate-Insulator Configuration

Abstract

In this study, we developed polymer gate insulator-based organic phototransistors (p-OPTs) with improved optical switching properties by using a hybrid gate insulator configuration. The hybrid gate insulator of our p-OPT has a photoresponsive layer made of poly(4-vinylphenol) (PVP), which enhances the photoresponse, and an interfacial layer of poly(methyl methacrylate) for reliable optical switching of the device. Our hybrid gate insulator-equipped p-OPT exhibits well-defined optical switching characteristics because no specific type of charge is significantly trapped at an interfacial layer/organic semiconductor (OSC) interface. Moreover, our device is more photoresponsive than the conventional p-OPT (here, an OPT with a single-polymer poly(methyl methacrylate) (PMMA) gate insulator), because the characteristic ultraviolet (UV) absorption of the PVP polymer allows the photoresponsive layer and OSC to contribute to the generation of charge carriers when exposed to UV light.

Polymer Insulator Processing‐Organic Transistor Performance Relationship Investigated through Admittance Spectroscopy

“…On the contrary, PMMA generates smaller grains, causing the increase of interface traps and OSC resistivity and transport dispersion. [ 10 ] Finally, the low density of interface traps in sample D, which favored the conductivity increase and the V ON reduction, shows that the addition of UV treatment improved not only the copolymer insulating properties and stability, but also the interface quality and the semiconductor structural order.…”

“…Indeed, the presence of the PMMA film in the device B effectively improves the dielectric insulating capacity, blocking charge carrier injection from the channel, as is evident from the reduction of the OTFT leakage current and hysteresis width. [ 10 ]…”

A Review on Solution-Processed Organic Phototransistors and Their Recent Developments

“…Similarly to these results, the R-value of PMMA-modified OPT was the lowest of them all (R max,PMMA = 223 mA W −1 , R max,PVP = 303 mA W −1 and R max,unmodified = 761 mA W −1 ). Moreover, Park et al [104] surveyed hybrid gate insulators (PVP-PMMA) on UV-sensing by comparing them to the conventional single-layered dielectric (PMMA). PVP was chosen due to its high sensitivity to UV light and its insulating capability.…”

A Review on Solution-Processed Organic Phototransistors and Their Recent Developments

“…Moreover, Park et al [104] surveyed hybrid gate insulators (PVP-PMMA) on UV-sensing by comparing them to the conventional single-layered dielectric (PMMA). PVP was chosen due to its high sensitivity to UV light and its insulating capability.…”