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

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.