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제124회 대한화학회 학술발표회, 총회 및 기기전시회 안내 Gap-dependent diffusion kinetics for molecular hole dopants through MX2-substrate

2019년 8월 29일 15시 45분 56초
PHYS.P-214 이곳을 클릭하시면 발표코드에 대한 설명을 보실 수 있습니다.
10월 17일 (목요일) 11:00~12:30
Physical Chemistry
저자 및
Haneul Kang, Sunmin Ryu*
Department of Chemistry, Pohang University of Science and Technology, Korea
Understanding molecular behavior in nanometer-scale confinement is important in various scientific fields and technological applications of low-dimensional material systems. In particular, interfacial molecular diffusion is known to be a key step of ambient charge transfer (CT) doping in two-dimensional materials supported on substrates. Its detailed mechanism and kinetics, however, have yet to be revealed. In this work, we investigated the space-resolved kinetics of CT in single-layer (1L) transition metal dichalcogenides (TMDs) of MX2 (M = Mo, W and X = S, Se) using a redox reaction model where O2/H2O couples serve as a hole dopant.[1] As a charge density probe, photoluminescence (PL) spectroscopy and imaging were applied to four different TMDs supported on SiO2 in a gas-controlled optical cell. For all TMDs, oxygen gas induced hole carriers, which could be reversed in Ar atmosphere. Interfacial diffusion of the molecular dopants was confirmed by spatial propagation of change in PL intensity from edges towards centers of samples. We also found that the diffusion was accelerated for samples with larger interfacial gaps between TMDs and supporting substrates. TMDs supported on sapphire and mica substrates will also be discussed in regard with possible roles of confined water layers in the CT reactions. [1] V. Chakrapani, J. C. Angus, A. B. Anderson, S. D. Wolter, B. R. Stoner, G. U. Sumanasekera, Science 318, 1424 (2007)