[SID Symp. Dig. Tech.] Ultrapure Green Light‐Emitting Diodes using Colloidal Quantum Wells of Hybrid Lead Halide Perovskites
We present our view about the perovskite colloidal quantum wells in next-generation LEDs.
Pure green light emitting diodes (LEDs) are essential to realize an ultra-wide color gamut in the next-generation displays, as is defined by the Rec. 2020 standard. However, because the human eye is more sensitive to the green spectral region, it is not yet possible to achieve an ultra-pure green electroluminescence (EL) with sufficiently narrow bandwidth that covers >95% of the Rec. 2020 standard in the CIE 1931 color space. Here, we demonstrate efficient, ultra-pure green EL based on the colloidal quantum wells (CQWs) of organic-inorganic lead bromide perovskites. Through the dielectric-quantum-well (DQW) engineering and their aggregation-induced emssion behaviors, the quantum-confined CQWs exhibit a high exciton binding energy of 162 meV, resulting in a high photoluminescence quantum yield (PLQY) of ~95% in the spin-coated films. Our optimized LED devices show a maximum current efficiency (ηCE) of 21 cd A-1, which is about 50% higher than the highest efficiency ever reported in all colloidal perovskite nanocrystal-based LEDs, matching the performance of fluorescent organic LEDs. The CIE 1931 color coordinates of (0.168, 0.773), covering 97% of the Rec. 2020 standard in the CIE 1931 color space, representing the “greenest” LEDs ever reported.