Stable Binary Complementary White Light-Emitting Diodes Based on Quantum-Dot/Polymer-Bilayer Structures

A binary complementary white light-emitting diode (LED) was designed and fabricated by employing a colloidal quantum-dot (QD)/polymer-bilayer configuration in the device active region. Stable white electroluminescence is observed from the cumulative emission of the yellow-emitting CdSe–ZnS core-shell QDs and blue-emitting poly(N,N'-bis (4-butylphenyl)-N,N'-bis(phenyl)benzidine) (Poly-TPD) molecules. The white chromaticity of the LED output can be tailored by varying the respective thicknesses of the constituent emissive layers; whereas the emission color exhibits little dependence on the applied bias over a wide voltage range. The maximum luminance of the device reaches 2600 cd/m$^{2}$ under a bias of 9.4 V.