Polarity-Mediated Antisolvent Control Enables Efficient Lanthanide-Based near-Infrared Perovskite LEDs.

Pan, Jia-Lin; Shen, Wan-Shan; Li, Sheng-Nan; Zhang, Zhong-Da; Zhao, Feng; Duan, Hong-Wei; Wang, Ya-Kun; Liao, Liang-Sheng · Nano Lett · 2024

basic_science · Level V

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Abstract

Alloying lanthanide ions (Yb<sup>3+</sup>) into perovskite quantum dots (Yb<sup>3+</sup>:CsPb(Cl<sub>1-<i>x</i></sub>Br<sub><i>x</i></sub>)<sub>3</sub>) is an effective method to achieve efficient near-infrared (NIR) luminescence (>950 nm). Increasing the Yb<sup>3+</sup> alloying ratio in the perovskite matrix enhances the luminescence intensity of Yb<sup>3+</sup> emission at 990 nm. However, high Yb<sup>3+</sup> alloying (>15%) results in vacancy-induced inferior material stability. In this work, we developed a polarity-mediated antisolvent manipulation strategy to resolve the incompatibility between a high Yb<sup>3+</sup> alloying ratio and inferior stability of Yb<sup>3+</sup>:CsPb(Cl<sub>1-<i>x</i></sub>Br<sub><i>x</i></sub>)<sub>3</sub>. Precise control of solution polarity enables increased uniformity of the perovskite matrix with fewer trap densities. Employing this strategy, we obtain Yb<sup>3+</sup>:CsPb(Cl<sub>1-<i>x</i></sub>Br<sub><i>x</i></sub>)<sub>3</sub> with the highest Yb<sup>3+</sup> alloying ratio of 30.2% and a 2-fold higher electroluminescence intensity at 990 nm. We lever the engineered Yb<sup>3+</sup>:CsPb(Cl<sub>1-<i>x</i></sub>Br<sub><i>x</i></sub>)<sub>3</sub> to fabricate NIR-LEDs, achieving a peak external quantum efficiency (EQE) of 8.5% at 990 nm: this represents the highest among perovskite NIR-LEDs with an emission wavelength above 950 nm.