Visible-Light-Responsive Organic Synaptic Devices Based on Rhodamine B-Doped Source-Gated Transistors
Yonghee Kim, Chang Min Lee, Eun Kwang Lee
Abstract
Organic artificial synaptic devices replicating biological neurons in sensing, transporting, and storing information with energy efficiency are gaining attention to next-generation computing circuits. Previous studies report that organic electrochemical transistors (OECTs) with polymeric semiconductors show inconsistent structure-synaptic properties. Also, OECTs with small molecular semiconductors demonstrate performance degradation by hydrophilic ions. This study develops low-power and high-performance organic photoneuromorphic devices based on n -type small molecular semiconductor of BPE-PTCDI doped with Rhodamine B (RhoB, an organic cationic dye) and a source-gated transistor (SGT) structure. Organic SGTs (OSGTs) with RhoB exhibit a high photoresponsivity of 2.07 × 10 3 A W –1 induced by charge transfer from RhoB in visible light and a low-power operation induced by the Schottky barrier. OSGTs exhibit 3.70 × 10 3 times higher photoresponsivity per drive power (4.92 × 10 8 A W –2 ) than typical field-effect transistors. The OSGTs achieve synaptic properties at 1 V electrical pulsed stimulation by thinning the Schottky barrier of the SGT, high paired-pulse facilitation per driving power (3.20 × 10 11 % W –1 ), and pulsed photo-synaptic properties using hole trap by RhoB doping. These findings suggest potential technology for low-power auxiliary electronics for glaucoma patients and light trauma treatment and thus contribute to improving the quality of human life.