Dual-Wavelength Electroluminescent QLEDs Composedof Mixed Alloyed Quantum Dots

Feasible electroluminescent quantum dot light-emitting diodes (QLEDs) fabricated by a single spin coating of dual monochromatic alloyed quantum dots (QDs) were investigated and compared in this study. All the devices were fabricated in the same structure of indium tin oxide/poly­(3,4-ethylenedioxythiophene) polystyrene sulfonate/poly­[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl))­diphenylamine)] (ITO/PEDOT:PSS/TFB)/mixed-QDs/ZnO/Al with single mixed-QDs emissive layer, which possessed controllable dual emission spectra and provided flexibility and applicability in practical applications. By selecting two of blue ZnCdS, green ZnCdSeS, yellow core/shell ZnCdSeS/ZnS, and red core/shell ZnCdSeS/ZnSeS QDs with suitable surface modifications to ensure similar surface chemistry, devices could exhibit dual emission peaks with various color compositions such as deep yellow, red-pink, ocean blue, and pure white light with luminance as high as 6970 cd/m2, and the color coordinate could be feasibly adjusted by either applied voltages or QD weight ratio. It was also observed that the similarity of QD chemical composition appeared to influence the electroluminescent wavelength, which was ascribed to a local like–like aggregation in the mixed-QD film in the devices.