High-Efficiency Pure-Red CsPbI₃ Quantum Dot Light-Emitting Diodes Enabled by Strongly Electrostatic Potential Solvent...

Efficient pure-red emission light-emitting diodes (LEDs) are essential for high-definition displays, yet achieving pure-red emission is hindered by challenges like phase segregation and spectral instability when using halide mixing. Additionally, strongly confined quantum dots (QDs) produced through traditional hot-injection methods face byproduct contamination due to poor solubility of metal halide salts in the solvent octadecene (ODE) at low temperatures. Herein, we introduced a novel method using a benzene-series strongly electrostatic potential solvent instead of ODE to prevent PbI₂ intermediates and promote their dissolution into [PbI₃]^-. Increasing methyl groups on benzene yields precisely sized (4.4 ± 0.1 nm) CsPbI₃ QDs with exceptional properties: a narrow 630 nm PL peak with photoluminescence quantum yield (PLQY) of 97%. Sequential ligand post-treatment optimizes optical and electrical performance of QDs. PeLEDs based on optimized QDs achieve pure-red EL (CIE: 0.700, 0.290) approaching Rec. 2020 standards, with an EQE of 25.2% and T₅₀ of 120 min at initial luminance of 107 cd/m².