Efficient and Color Stable White Quantum-Dot Light-Emitting Diodes with External Quantum Efficiency Over 23%

White quantum dot light-emitting diodes (WQLEDs) with different structures are developed. By mixing red (R), blue (B) and green (G) quantum dots (QDs) together, the optimal WQLEDs exhibit a peak current efficiency (CE) of 22.54 cd/A and an external quantum efficiency (EQE) of 7.07%. The relatively poor performance is due to the efficient nonradiative Forster resonant energy transfer (FRET) among B-, G- and R-QDs. To address this issue, tandem WQLEDs are developed. By stacking the blue and the yellow QLEDs, the two-unit tandem WQLEDs exhibit a peak CE of 30.3 cd/A and a maximum EQE of 15.2%. To further improve the color stability and the efficiency, the R/G/B three-unit tandem WQLEDs are developed, which exhibit an impressive CE of 55.06 cd/A, a high EQE of 23.88% and a high luminance of 65690 cd/m(2), which are the highest values ever reported. Moreover, the optimal tandem WQLED exhibits a high color stability, a pure white color with a 1931 Commission International de I'Eclairage (CIE) coordinate of (0.33, 0.34) and a color rendering index of 80. The demonstrated tandem WQLEDs, with high efficiency, pure white color, high color stability and high color-rendering, would be promising candidates for next generation solid-state lighting and full-color display.