Nanotechnology

Nanocrystal

Coating

Engineering

Perovskite (structure)

Nanoparticle

Composite material

Light-emitting diode

Metallurgy

Materials science

Oxide

Diode

Photoluminescence

Chemical engineering

Optoelectronics

Nanometre

Advanced Functional Materials

Significant advances are realized in perovskite‐converted hybrid light‐emitting diodes (pc‐HLEDs). However, long‐living devices at high efficiencies still represent a major milestone with average stabilities of &lt; 200 h at ≈ 50 lm W −1 under low applied currents ( &lt; 15 mA). Herein, a dual metal oxide‐coated CsPbBr 3 @SiO 2 /ZrO 2 composite is prepared in a one‐pot synthesis through the kinetic control of the sol–gel reaction, followed by a gentle drying process in air. These hybrid nanoparticles show photoluminescence quantum yields of ≈ 65% that are stable under temperature, ambient, and irradiation stress scenarios. This is translated to pc‐HLEDs with a near‐unity conversion efficiency at any applied current, high efficiencies around 75 lm W −1 , and one of the most remarkable stabilities of ≈ 200 and 700 h at 100 and 10 mA, respectively. In addition, the device degradation mechanism is thoughtfully rationalized comparing devices operating under ambient/inert conditions. As such, this work provides three milestones: i) a new room temperature one‐pot protocol to realize the first SiO 2 /ZrO 2 metal oxide coating that effectively protects the emitting perovskite nanoparticle core, ii) one of the most stable and efficient pc‐HLEDs operating under ambient condition at any applied current, and iii) new insights for the degradation of pc‐HLEDs.

Meeting High Stability and Efficiency in Hybrid Light‐Emitting Diodes Based on SiO2/ZrO2 Coated CsPbBr3 Perovskite Nanocrystals