Spectrally Stable Pure Red CsPbI_3 Quantum Dots Light-Emitting Diodes via Effective Low Temperature Gradient Centrifugation Separation and Surface Modification

摘要

Development of high-performance and stable pure red perovskitelight-emitting devices (LEDs) promotes commercialization of perovskite.Benefiting from the quantum confinement effect, pure red CsPbI_3 quantumdots (QDs) can avoid the color drift issue for mixed halide systems. Herein, afacile temperature-dependent hot-injection method combined with lowtemperature gradient centrifugation is employed to prepare 5.60 ± 0.05 nmpure red QDs. The QDs exhibit 642 nm photoluminescence (PL) with 37 nmfull width at half maximum, and their Commission Internationale del’Eclairage (CIE) coordinates located at (0.708, 0.292) match well withstandard pure red for Rec. 2020. The PL half-lifetime for pure red QDssolution is 210 days under ambient conditions, and both the X and Ycoordinates of CIE only fluctuate within (0.002, 0.002). Finally, a simple NH_4Ipost-treatment to decrease ligand length further boosts the QDs conductivity,and the pure red LED exhibits 9.4 maximum external quantum efficiency.The electroluminescence spectra exhibits a sharp peak at 645 nm, and theirCIE coordinates are located at (0.707, 0.290). Furthermore, the pure red LEDexhibits both good working and color stability. Its half-lifetime is 25.1 min andcolor drifts are only (0.002, 0.002) after 30.0 min of continuous working at60 cd m~(?2) with a constant current density of 3.5 mA cm~(?2).