A zinc non-halide dopant strategy enables efficient perovskite CsPbI3 quantum dot-based light-emitting diodes

Metal ion doping has been considered as one of the most effective methods to achieve highly efficient perovskite light-emitting diodes (LEDs), which is significant for future high-definition displays and high-quality lighting. However, its exact function is still uncertain because the doping of metal ions is also accompanied by the introduction of halide ions and halide-rich circumstances, which can enhance the optoelectronic properties as well. In this work, a zinc non-halide dopant strategy was employed to specifically study the effect of Zn2+ on CsPbI3 quantum dots (QDs). We confirmed that Zn2+ was doped into the perovskites interstitially via X-ray diffraction (XRD) and pair distribution function (PDF) analysis. Zn2+-doped CsPbI3 QDs exhibited higher emission properties with 120% enhancement in the photoluminescence quantum yield (PLQY) compared with pristine CsPbI3 QDs. The Zn2+-doped CsPbI3 QD-based LEDs (QLEDs) showed nearly two-fold increase in the external quantum efficiency (EQE) versus the control device, and it improved from 7.5% to 14.6%. Besides, a maximum current efficiency of 0.83 cd A−1 and the highest luminance of 378 cd m−2 were achieved. These results certify that Zn2+ doping enables high-performance QLEDs without the introduction of halide ions, which is beneficial for the further research on doped perovskite fields and lays the foundation for the future practical applications of QLEDs.