Highly spectra-stable pure blue perovskite light-emitting diodes based on copper and potassium co-doped quantum dots
Fang Chen, Wenjie Ming, Yongfei Li, Yun Gao, Lea Pasquale, Kexin Yao, Boyuan Huang, Qiuting Cai, Guochao Lu, Jizhong Song, Mirko Prato, Xingliang Dai, Haiping He, Zhizhen Ye
Abstract
Halide perovskite light emitting diodes (LEDs) have gained great progress in recent years. However, mixed-halide perovskites for blue LEDs usually suffer from electroluminescence (EL) spectra shift at a high applied voltage or current density, limiting their efficiency. In this work, we report a strategy of using single-layer perovskite quantum dots (QDs) film to tackle the electroluminescence spectra shift in pure-blue perovskite LEDs and improve the LED efficiency by co-doping copper and potassium in the mixed-halide perovskite QDs. As a result, we obtained pure-blue halide perovskite QD-LEDs with stable EL spectra centred at 469 nm even at a current density of 1,617 mA·cm−2. The optimal device presents a maximum external quantum efficiency (EQE) of 2.0%. The average maximum EQE and luminance of the LEDs are 1.49% and 393 cd·m−2, increasing 62% and 66% compared with the control LEDs. Our study provides an effective strategy for achieving spectra-stable and highly efficient pure-blue perovskite LEDs.