Quantum-dot-based LEDs are characterized by pure and saturated emission colours with narrow bandwidth, and their emission wavelength is easily tuned by changing the size of the quantum dots. However, the brightness, efficiency and lifetime of LEDs need to be improved to meet the requirements of commercialization in the near future. Here, we report red, orange, yellow and green LEDs with maximum luminance values of 9,064, 3,200, 4,470 and 3,700 cd m−2, respectively, the highest values reported so far. Solution-processable core–shell quantum dots with a CdSe core and a ZnS or CdS/ZnS shell were used as emissive layers in the devices. By optimizing the thicknesses of the constituent layers of the devices, we were able to develop quantum-dot-based LEDs with improved electroluminescent efficiency (1.1–2.8 cd A−1), low turn-on voltages (3–4 V) and long operation lifetimes. These findings suggest that such quantum-dot-based LEDs will be promising for use in flat-panel displays.
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This work was supported by the Ministry of Science and Technology of China (973 project, No. 2002CB613404) and NSFC (No. 20421101 and 50633050). Y.A.W. acknowledges funding from the National Science Foundation SBIR program (award number: 0638209). We thank Ghassan Jabbour for the calculation of the CIE of the QD-LED emission.
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Sun, Q., Wang, Y., Li, L. et al. Bright, multicoloured light-emitting diodes based on quantum dots. Nature Photon 1, 717–722 (2007) doi:10.1038/nphoton.2007.226
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