Enhanced luminescence through doping of CuInZnS core-shell quantum dots with Eu

Abstract

Due to the quantum confinement effect, the quantum dots (QDs) behave distinguished photo-/electro-luminescence property. However, due to so small size with 3–5 nm diameter, their surface defects cause spectral limitation and luminescent instabilities, which inhibited the applications of QDs in key areas. It should be very interesting if rich luminescence spectra of lanthanides can be used to enhance the emission and to extend the spectra of sulfide-base QDs. However, the sulfur repellency of lanthanide ions (such as Eu³⁺) is the negative factor. In this work, we incorporated lanthanide ions (Eu³⁺) complexes into QDs to realize this. Diketone (i.e., acetylacetone (ACAC)) and phenanthroline (Phen) were chosen as the ligands of Eu³⁺ (i.e., Eu) chlorides. The experimental data indicated that the incorporating Eu³⁺ complexes into the ZnS-modified CIZS QDs resulted in double enhancement of the luminescent intensity, the blue-shift of emission wavelength from 637 to 575 nm, the PLQY increase from 55.94 % to 81.56 %. Simultaneously, the Zn²⁺ in the shell, under the influence of the Eu³⁺, reacted with oxygen vacancies in the environment. XRD shows the characteristic peaks of ZnO, indicating the formation of ZnO QDs.