Enhancing the Performance and Stability of Perovskite Nanocrystal Light‐Emitting Diodes with a Polymer Matrix

All-inorganic perovskite nanocrystal materials exhibit excellent light-emitting properties in the visible range with narrow-band emissions, relatively high stability levels, and high photoluminescence quantum efficiency. A uniform morphology of perovskite nanocrystal film is necessary to realize highly efficient light-emitting devices, but the morphology of CsPbX3 nanocrystal films has not been intensively studied. Here, a novel method is presented to obtain uniform and stable CsPbBr3 nanocrystal film through a drop-casting method with a poly(methyl methacrylate) (PMMA) matrix. The introduction of CsPbBr3 nanocrystal:PMMA composite film into a perovskite nanocrystal light-emitting diode (PeNLED) brings enhanced device performance with good coverage of green electroluminescence (EL) emission. Moreover, the long-term stability of the PeNLED is improved by the presence of the PMMA due to the resulting considerable water resistance and good thermal stability. Much less EL blinking is also observed from PeNLEDs with the CsPbBr3 nanocrystal:PMMA composite film as compared to the amount with perovskite bulk film under a continuous bias condition. Therefore, it is emphasized that the enhanced efficiency and stability of PeNLEDs by the CsPbBr3 nanocrystal:PMMA composite film can further promote their usage in displays and in lighting applications.