Kim, Byung Jun Cho, Nam-Kwang Park, Sungho Jeong, Shinyoung Jeon, Dohyeon Kang, Yebin Kim, Taekyeong Kim, Youn Sang Han, Il Ki Kang, Seong Jun 2024-01-19T17:34:07Z 2024-01-19T17:34:07Z 2021-09-05 2020-04-28 2046-2069 https://pubs.kist.re.kr/handle/201004/118710 Highly transparent optical logic circuits operated with visible light signals are fabricated using phototransistors with a heterostructure comprised of an oxide semiconductor (ZnO) with a wide bandgap and quantum dots (CdSe/ZnS QDs) with a small bandgap. ZnO serves as a highly transparent active channel, while the QDs absorb visible light and generate photoexcited charge carriers. The induced charge carriers can then be injected into the ZnO conduction band from the QD conduction band, which enables current to flow to activate the phototransistor. The photoexcited charge transfer mechanism is investigated using time-resolved photoluminescence spectroscopy, scanning Kelvin probe microscopy, and ultraviolet photoelectron spectroscopy. Measurements show that carriers in the QD conduction band can transfer to the ZnO conduction band under visible light illumination due to a change in the Fermi energy level. Moreover, the barrier for electron injection into the ZnO conduction band from the QD conduction band is low enough to allow photocurrent generation in the QDs/ZnO phototransistor. Highly transparent NOT, NOR, and NAND optical logic circuits are fabricated using the QDs/ZnO heterostructure and transparent indium tin oxide electrodes. This work provides a means of developing highly transparent optical logic circuits that can operate under illumination with low-energy photons such as those found in visible light. English ROYAL SOC CHEMISTRY LOW-TEMPERATURE SOLAR-CELLS PHOTODETECTOR COMMUNICATION PERFORMANCE Highly transparent phototransistor based on quantum-dots and ZnO bilayers for optical logic gate operation in visible-light Article 10.1039/d0ra01756f 1 RSC ADVANCES, v.10, no.28, pp.16404 - 16414 RSC ADVANCES 10 28 16404 16414 scie scopus 000555042000019 2-s2.0-85084313231 Chemistry, Multidisciplinary Chemistry Article LOW-TEMPERATURE SOLAR-CELLS PHOTODETECTOR COMMUNICATION PERFORMANCE phototransistor transparent quantum-dots ZnO bilayer optical logic gate visible light