High-Efficiency Pure-Red CsPbI<sub>3</sub> Quantum Dot Light-Emitting Diodes Enabled by Strongly Electrostatic Potential Solvent and Sequential Ligand Post-treatment Process.

Hu, Jingcong; Bi, Chenghao; Ren, Ke; Zhang, Xuetao; Wang, Weiqiang; Ma, Sai; Wei, Mingzhi; Lu, Yue et al. · Nano Lett · 2024

basic_science · Level V

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Abstract

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 PbI<sub>2</sub> intermediates and promote their dissolution into [PbI<sub>3</sub>]<sup>-</sup>. Increasing methyl groups on benzene yields precisely sized (4.4 ± 0.1 nm) CsPbI<sub>3</sub> 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 <i>T</i><sub>50</sub> of 120 min at initial luminance of 107 cd/m<sup>2</sup>.