Enhanced performance of inverted CsPbBr3 nanocrystal LEDs via Zn(II) doping

Perovskite lighting-emitting diodes (PeLEDs) with inverted structure have been considered as promising display technology due to their suitable driving schemes with n-type thin-film transistors. However, the defects and imbalanced charge carriers in the CsPbBr3 nanocrystal (NC) PeLED are key hurdles, limiting the performance. Herein, we have successfully doped Zn2+ ions into CsPbBr3 NCs by ligand-assisted reprecipitation method, exhibiting an 85% enhancement of the photoluminescence quantum yield (PLQY). In addition, the optimized energy level alignment via Zn doping facilitates the carrier balance in the devices, improving the efficiencies. The obtained CsPbBr3:Zn-based PeLED reaches a high luminance of 3124 cd/m2 and a maximum external quantum efficiency (EQE) of 0.85%, which are superior to those of CsPbBr3-based PeLED (luminance = 564 cd/m2, EQE = 0.09%). The results demonstrate that Zn doping significantly enhances the performance of PeLED, which increases the potential of these inverted PeLEDs connected with n-type TFTs towards practical applications.