Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan.
Science and Technology Research Laboratories, Japan Broadcasting Corporation (NHK), Setagaya-ku, Tokyo 157-8510, Japan.
J Chem Phys. 2023 Apr 28;158(16). doi: 10.1063/5.0144271.
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.
通过控制量子点的铜（Cu）分数，即 Cu/(In+Ga)，以及组成量子点的铟（In）与镓（Ga）的比例，可以缩小量子点发光二极管（QD-LED）的发射峰半高宽并调节峰位，从而改善显示设备的色度和颜色精度。在这项研究中，我们通过控制铜（Cu）分数，即 Cu/(In+Ga)，以及组成量子点的铟（In）与镓（Ga）的比例，开发了具有较窄光致发光（PL）峰的多元铜铟镓硫（CIGS）量子点。随着 In/(In+Ga) 比例从 1.0 降低到 0.7，CIGS 量子点的能隙从 1.74 eV 增大到 2.77 eV。PL 强度显著依赖于 Cu 分数，PL 峰半高宽取决于 In/(In+Ga) 比值。当 Cu/(In+Ga) 比为 0.3，In/(In+Ga) 比为 0.7 时，制备的 CIGS 量子点的 PL 峰最尖锐，位于 668nm，半高宽为 0.23 eV，明显窄于以前报道的 CIGS 量子点的半高宽（>0.4 eV）。通过 GaSx 和 Ga-Zn-S 壳层表面涂覆，CIGS 量子点的 PL 量子产率从 8.3%分别提高到 27%和 46%，而 PL 峰没有变宽。考虑到较大的斯托克斯位移（>0.5 eV）和主要的 PL 衰减分量（200-400 ns），窄 PL 峰可归因于带隙内态的发射。用 GaSx 壳层表面涂覆的 CIGS 量子点制备的 QD-LED 发出 688nm 的红光，发射峰半高宽为 0.24 eV。
