Enhancing the Brightness of Cesium Lead Halide Perovskite Nanocrystal Based Green Light-Emitting Devices through the Interface Engineering with Perfluorinated Ionomer.

High photoluminescence quantum yield, easily tuned emission colors, and high color purity of perovskite nanocrystals make this class of material attractive for light source or display applications. Here, green light-emitting devices (LEDs) were fabricated using inorganic cesium lead halide perovskite nanocrystals as emitters. By introducing a thin film of perfluorinated ionomer (PFI) sandwiched between the hole transporting layer and perovskite emissive layer, the device hole injection efficiency has been significantly enhanced. At the same time, PFI layer suppressed charging of the perovskite nanocrystal emitters thus preserving their superior emissive properties, which led to the three-fold increase in peak brightness reaching 1377 cd m(-2). The full width at half-maximum of the symmetric emission peak with color coordinates of (0.09, 0.76) was 18 nm, the narrowest value among perovskite based green LEDs.