123rd General Meeting of the KCS

Type Oral Presentation
Area Oral Presentation of Young Material Chemists
Room No. Room 405+406
Time THU 09:48-10:00
Code MAT.O-5
Subject Direct Sensing from Self-Doped Colloidal Quantum Dots Thin-Film Transistor
Authors Dongsun Choi, Kwang Seob Jeong*
Department of Chemistry, Korea University, Korea
Abstract Colloidal quantum dots (CQDs) have attracted much attention because of the tunability of electronic transition. Recently, the studies on the intraband transition of the CQDs, which directly uses the quantized energies in a band, are actively carried out. These studies have revealed that the intraband transition is a result of the self-doping phenomenon and are sensitive to the surface dipole change. In this presentation, I will present the self-doping properties and direct sensing mechanism of the self-doped HgSe CQD/ZnO TFT sensor. The HgSe CQDs are spin-coated over the ZnO thin-film transistor without any other receptor molecule. Surprisingly, HgSe CQD/ZnO TFT sensor had multifunctional sensitivity to the CO2, NO, and H2S gases, mid- IR photons, and L-cysteine molecule. To note, the CO2 and NO gas molecules are physisorbed to the surface of HgSe CQD film and showed high reversibility in threshold voltage under a repetitive experiment. The mid-IR intraband transition of HgSe CQDs film undergoes energy transfer with the vibrational mode of gas molecules. The electronic-vibrational energy transfer (EVET) mechanism is plausible because the vibrational energy of the gas and the intraband transition have similar energy gap. On the other hand, the chemisorption result, irreversibility, is measured with H2S gas and L-cysteine, which forms the bond between film and thiol functional group. The intraband CQDs have much potential for future sensor materials because of the easy reproductivity and low-cost fabrication process.
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