Perovskite nanocrystals (NCs) are promising lightemitting materials for next-generation illuminations and displays. The main challenge for practical applications is to achieve high durability. Herein, a hybrid passivation strategy was developed to simultaneously enhance the photoluminescence quantum yield (PLQY) and the stability of perovskite CsPbBr 3 NCs by two-step modification with surface halogen replenishment and atomic layer deposition. The hybrid passivation mechanisms regarding the repairing of NCs' surface Pb−Br octahedron as well as insertion of inorganic AlO x on the NCs' surface were unraveled. The obtained CsPbBr 3 NC films not only have high PLQY but also retain 100% of original PL value after UV illumination for 48 h, which was quantitatively assessed as the most stable solid-state CsPbBr 3 NC film ever reported. Based on the passivation method, a high-lumen white light-emitting diode (LED) device exhibiting working durability was successfully fabricated. This strategy is beneficial for fabricating ultrastable perovskite phosphors and significantly improving their potential in LED illumination and backlight displays.

Carrier balance and ion diffusive inhibition are crucial to the external quantum efficiency (EQE) and stability of perovskite quantum dot light-emitting diodes (PQLEDs). Herein, an inorganic ZnBr2 ligand is used to passivate the Br vacancy on the surface of the perovskite quantum dots and, thus, near-unity photoluminescence quantum yield is achieved. With respect to energy alignment and carrier balance, poly­[bis­(4-phenyl) (4-butylphenyl) amine] (poly-TPD) is chosen to match with 1,3,5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene (TPBi), and the fabricated PQLEDs exhibit the maximum luminance as high as 92,279 cd m–2. In addition, an ultrathin Al2O3 layer is introduced between indium tin oxide (ITO) and poly­(ethylene dioxythiophene):polystyrene sulfonate (PEDOT:PSS) via atomic layer deposition (ALD). The Al2O3 buffer layer can precisely control the hole transmission rate, balance the carrier injection, and realize the improvement of EQE from 2.86 to 4.81%. The T 50 lifetime of the device is extended by about 30 times due to suppression of metal ion diffusion from ITO to the emission layer. Our work demonstrates the promising fabrication of highly efficient and stable PQLEDs via ALD interface engineering.

Perovskite nanocrystal (PNC) suffers from solution corrosion and water/oxygen oxidation when used in light‐emitting diodes (LEDs). Atomic layer deposition (ALD) is applied to introduce Al2O3 infilling and interface engineering for the CsPbBr3 nanocrystal emission layers, and the inorganic electron transport layer‐based CsPbBr3–ZnMgO LED device is fabricated. The introduction of Al2O3 ALD layers significantly improves the tolerance of CsPbBr3 PNC thin films to polar solvents ethanol of ZnMgO during spin coating. The operation lifetime of ALD‐treated CsPbBr3 PNC–ZnMgO LED is prolonged to about two orders of magnitude greater than that of the CsPbBr3 PNC‐TPBi LED device with a largely improved external quantum efficiency (EQE) value. Moreover, the infilling of Al2O3 into the CsPbBr3 layer boosts the carrier mobility for more than 40 times inside the light‐emission layer. However, the interfacial carrier transport between different functional layers is hindered by the insulated Al2O3 layer, which provides an effective barrier for excess electron transport. Such a favorable band alignment facilitates the carrier balance of the device and contributes to the improved electroluminescent performance of the device with ALD Al2O3 interface engineering, which is further supported by theoretical device modeling. Herein, a facile method is provided to fabricate PNC‐LED devices with both high efficiency and long‐term lifetime.

A facile colloidal layer-by-layer deposition of amorphous AlO x is applied on the CsPbBr3 perovskite nanocrystals (PNCs). The CsPbBr3 PNCs show improved photoluminescence intensity and excellent water resistance due to the fine control on the thickness of AlO x at the nanoscale. The irradiation induced by the mixing of the CsPbBr3 and CsPbI3 PNCs is well suppressed due to the inhibition of anion exchange. Moreover, the AlO x -treated CsPbBr3 PNCs are integrated into a light-emitting diode and the external quantum efficiency (EQE) is improved to 6.05% with a high luminance of 32,747 cd/m2 due to optimized band alignment. Additionally, the luminance T 50 lifetime of the fabricated device is prolonged by more than 4 times. This work provides a solution-compatible modification of colloidal PNCs to achieve high luminescence and stability, which is promising in the practical applications of PNC-based devices.

Perovskite quantum dots light-emitting diodes (PQLEDs) usually suffer from low efficiency due to the imbalanced carrier injection. Dual hole injection layers (HILs) with NiOx/polyethylene dioxythiophene:polystyrene sulfonate are applied to tune the carrier transport and recombination in fabricated PQLEDs. The fine control of the NiOx film enables the external quantum efficiencies of the PQLEDs to increase from 1.5% to 9.7%, and the lifetime of T50 at 400 cd/m2 is prolonged by about 13 times with the cooperation of dual HIL. The improved performance of PQLEDs is attributed to the achievement of favorable carrier transport balance and effective radiative recombination in the emission layer. We highlight the critical role of carriers balance via the HIL engineering on both the efficiency and stability of PQLEDs.