White-light-emitting diodes based on blue and green quantum-confined CsPbBr3 perovskite quantum dots and red CdSe quantum dots without ion-exchange issues

Abstract

CsPbBr₃ quantum dots with various diameters around the Bohr exciton radius and emission wavelengths between 460 nm to 520 nm were prepared. Quantum dots with diameters of 4–13 nm were characterized via their absorption spectra, photoluminescence spectra, X-ray diffraction patterns, and time-resolved photoluminescence. Binary mixture solutions and composite films composed of blue and green CsPbBr₃ quantum dots showed two emission peaks without anion-exchange issues. A solution of red CdSe quantum dots was added to the sky-blue binary mixture solution to form a ternary mixture solution with white emission. Three clear emission peaks were observed, and the CIE chromaticity coordinates (0.33, 0.31) were obtained. A QD–polymer composite film with white emission was prepared and stacked on a UV LED to demonstrate white LEDs. Besides, white LEDs with a single emissive layer were prepared from the ternary mixture solution. Three emission peaks and CIE coordinates of (0.34, 0.33) were obtained.