High-efficiency and ultrapure-green light emitting diodes using colloidal 2D perovskites (Conference Presentation)

Color-pure green emission is essential to realize next-generation vivid displays. Recently, solution-processed OIHPs are attracting increasing attention because of their narrow emission, and potential to be fabricated energy-efficient and low-cost in lighting and display applications. However, the perovskite light emitting diodes (LEDs) that approach Rec. 2020 standard green emission with a maximum current efficiency ≥15 cd/A have not been achieved by far. Here, we present ultrapure green LEDs based on quantum confined colloidal perovskite emitters. A spin-coated thin film of two dimensional (2D) perovskites demonstrates a high absolute photoluminescence quantum efficiency (PLQE ~ 94%). The resultant perovskite LEDs show a maximum current efficiency >20 cd/A by using a composite emission layer of colloidal 2D perovskites and poly(methyl methacrylate). As compared to Rec. 2020 standard color gamut, the green emission shows >97% color saturation in the 1931 CIE color space. We present ultra-flexible perovskite LEDs with a bending curvature radius of 2 mm by using a 50 μm thin polyimide substrate. We further demonstrate a high-efficiency large-area (30 mm2) device without compromising in the device performance. These devices show ultimate potential to realize low-cost, large-scale fabrication of the ultra-pure green LEDs for the next-generation of displays.