Thermal Conductive Encapsulation Enables Stable High-Power Perovskite-Converted Light-Emitting Diodes.

Significant progress has been achieved on perovskite nanocrystal (PNC)-converted light-emitting diodes (PcLEDs) with the development of surface encapsulations. However, achieving bright and long-living devices remains a challenge because the thermal isolation structure of the air barriers exacerbates heat accumulation inside PcLEDs. Here, we proposed a thermal conductive encapsulation for PNCs by embedding CsPbBr3 PNCs in layer-by-layer assembled boron nitride (BN) nanoplatelets through SiO2 crosslinking. This structure effectively suppresses the heat accumulation on PNCs and provides excellent air resistance, enabling the PNC-SiO2-BN composite to withstand 1000 h of photothermal annealing (under a 405 nm laser at 0.31 W cm-2, 80 °C in air) without showing obvious degradation. Green- and white-light PcLEDs were fabricated via on-chip encapsulation of PNC-SiO2-BN. The PcLEDs achieved the milestone in long-term stability (half-life time > 1000 h) at a high power density of ∼1.7 W cm-2 and displayed extradentary stability at ∼0.15 W cm-2 with constant light intensity within 1000 h of sustained illumination. The success in making thermal conductive composites will expedite the application of PNCs in LED backlights and other optoelectronic devices.