Zn-Alloyed CsPbI<sub>3</sub> Nanocrystals for Highly Efficient Perovskite Light-Emitting Devices.

Shen, Xinyu; Zhang, Yu; Kershaw, Stephen V; Li, Tianshu; Wang, Congcong; Zhang, Xiaoyu; Wang, Wenyan; Li, Daguang et al. · Nano Lett · 2019

basic_science · Level V

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Abstract

We alloyed Zn<sup>2+</sup> into CsPbI<sub>3</sub> perovskite nanocrystals by partial substitution of Pb<sup>2+</sup> with Zn<sup>2+</sup>, which does not change their crystalline phase. The resulting alloyed CsPb<sub>0.64</sub>Zn<sub>0.36</sub>I<sub>3</sub> nanocrystals exhibited an improved, close-to-unity photoluminescence quantum yield of 98.5% due to the increased radiative decay rate and the decreased non-radiative decay rate. They also showed an enhanced stability, which correlated with improved effective Goldschmidt tolerance factors, by the incorporation of Zn<sup>2+</sup> ions with a smaller radius than the Pb<sup>2+</sup> ions. Simultaneously, the nanocrystals switched from n-type (for CsPbI<sub>3</sub>) to nearly ambipolar for the alloyed nanoparticles. The hole injection barrier of electroluminescent LEDs was effectively eliminated by using alloyed CsPb<sub>0.64</sub>Zn<sub>0.36</sub>I<sub>3</sub> nanocrystals, and a high peak external quantum efficiency of 15.1% has been achieved.