119th General Meeting of the KCS

Type Poster Presentation
Area 물리화학
Room No. 포스터발표장
Time 4월 20일 (목요일) 11:00~12:30
Code PHYS.P-24
Subject Steady-state Mid-Infrared Intraband Transition Occurring in Conduction Band of Heavily Doped Colloidal β-HgS Quantum Dot
Authors 윤빛나, 정주연, 정광섭*
고려대학교 화학과, Korea
Abstract The mercury chalcogenide colloidal quantum dot (CQD) has been of interest due to the size tunable mid-infrared intraband transition. The first reported absorption spectrum of mercury sulfide CQDs by Jeong et al. in 2014 showed broad size distribution with FWHM over 750 cm-1. The large FWHM apparently mostly results from the non-uniform nanocrystal size. Also, a versatile ligand exchange which is essential for further applications was not achieved from conventional HgS CQD passivated with thiol ligands because of the strong binding strength of the thiol ligands to the nanocrystal surface. Here, we report HgS CQDs passivated with non-thiol ligands offering ligand versatility. In addition, the doping density of CQDs was finely controlled by post surface treatment with ions. The CQD film showing both intraband and bandgap energy depending on the surface treatment, is analogous to the n-p type CQD homojunction. Surprisingly, a novel second intraband transition (1Pe-1De), that had been hidden for the last three decades, was firstly observed from the HgS CQD film by using the FTIR microscope. The combined features of non-thiol passivated HgS CQDs, versatile surface modification, doping control in nanocrystals, and higher quantum state transition hold promise for the use of the heavily doped colloidal quantum dot for a number of applications such as space-communication light source, mid-infrared energy sensitized electrode, infrared detector, and infrared filter.
E-mail ybitna@korea.ac.kr