Development of Cu-In-Ga-S quantum dots with a narrow emission peak for red electroluminescence

Chang Jiang; Makoto Tozawa; Kazutaka Akiyoshi; Tatsuya Kameyama; Takahisa Yamamoto; Genichi Motomura; Yoshihide Fujisaki; Taro Uematsu; Susumu Kuwabata; Tsukasa Torimoto

doi:10.1063/5.0144271

Development of Cu-In-Ga-S quantum dots with a narrow emission peak for red electroluminescence

J Chem Phys. 2023 Apr 28;158(16):164708. doi: 10.1063/5.0144271.

Authors

Affiliations

¹ Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan.
² Science and Technology Research Laboratories, Japan Broadcasting Corporation (NHK), Setagaya-ku, Tokyo 157-8510, Japan.
³ Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan.
⁴ Innovative Catalysis Science Division, Institute for Open and Transdisciplinary Research Initiatives (ICS-OTRI), Osaka University, Suita, Osaka 565-0871, Japan.

PMID: 37096856
DOI: 10.1063/5.0144271

Abstract

Narrowing the emission peak width and adjusting the peak position play a key role in the chromaticity and color accuracy of display devices with the use of quantum dot light-emitting diodes (QD-LEDs). In this study, we developed multinary Cu-In-Ga-S (CIGS) QDs showing a narrow photoluminescence (PL) peak by controlling the Cu fraction, i.e., Cu/(In+Ga), and the ratio of In to Ga composing the QDs. The energy gap of CIGS QDs was enlarged from 1.74 to 2.77 eV with a decrease in the In/(In+Ga) ratio from 1.0 to 0. The PL intensity was remarkably dependent on the Cu fraction, and the PL peak width was dependent on the In/(In+Ga) ratio. The sharpest PL peak at 668 nm with a full width at half maximum (fwhm) of 0.23 eV was obtained for CIGS QDs prepared with ratios of Cu/(In+Ga) = 0.3 and In/(In+Ga) = 0.7, being much narrower than those previously reported with CIGS QDs, fwhm of >0.4 eV. The PL quantum yield of CIGS QDs, 8.3%, was increased to 27% and 46% without a PL peak broadening by surface coating with GaSx and Ga-Zn-S shells, respectively. Considering a large Stokes shift of >0.5 eV and the predominant PL decay component of ∼200-400 ns, the narrow PL peak was assignable to the emission from intragap states. QD-LEDs fabricated with CIGS QDs surface-coated with GaSx shells showed a red color with a narrow emission peak at 688 nm with a fwhm of 0.24 eV.