Color-tunable quantum-dot light emitting diode and its integration with GaN-based blue LED for smart white-light emission

White-light emission with tunable color temperature have potential applications in the fields of smart lighting and backlight. In this study, we introduced an electron blocking layer (EBL) between red and green emission layers (EMLs) in a quantum-dot light-emitting diode (QLED). The emitting color of QLED can be tuned from red to green as the carrier distribution and recombination region are regulated by the applied voltage. In addition, the color tunable QLED device was integrated with a GaN-based blue light emitting diode (LED), achieving a hybrid QLED/LED device for white-light emission. Under the alternate-current (AC) driving method, the QLED was forwardly driven while the LED was reversely biased, and thus, both devices can be independently addressed by the polarity of the AC driving voltage. The results showed that the color temperature of white-light emission can be tuned from 3102K (warm white) to 12853K (cold white) and the highest color rendering index (CRI) of 88.6 can be also achieved, exhibiting great prospects in the application of lighting.