Cubic Halide Double Perovskite Nanocrystals with Anisotropic Free Excitons and Self-Trapped Exciton Photoluminescence,The Journal of Physical Chemistry Letters

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Cubic Halide Double Perovskite Nanocrystals with Anisotropic Free Excitons and Self-Trapped Exciton Photoluminescence
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2022-12-29 , DOI: 10.1021/acs.jpclett.2c03482
Chao Wang ₁ , Mengjiao Sun ₁ , Hui Wang ₁ , Guangjiu Zhao ₁

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In this work, we first developed Cs₂KBiCl₆ cubic double perovskite nanocrystals and a series of morphologically isotropic double perovskite nanocrystals. Different contributions of different elements to self-trapped states were revealed by density functional theory. Meanwhile, these double perovskite nanocrystals exhibit the coexistence of free and self-trapped exciton dual-color photoluminescence. Femtosecond transient absorption spectroscopy can confirm that the double perovskite nanocrystals produce a relatively obvious structural deformation in the excited state. We infer that this can lead to a large deviation of the excitation and emission transition dipoles, thus causing large photoluminescence anisotropy. Most importantly, we observe for the first time that both free exciton emission and self-trapped exciton emission are highly anisotropic, which are comparable to or even better than that of lead halide perovskites. This research paves the way for exploring more possibilities and practical applications.

中文翻译：

具有各向异性自由激子和自陷激子光致发光的立方卤化物双钙钛矿纳米晶

在这项工作中，我们首先开发了 Cs ₂ KBiCl ₆立方双钙钛矿纳米晶和一系列形态各向同性的双钙钛矿纳米晶。密度泛函理论揭示了不同元素对自陷态的不同贡献。同时，这些双钙钛矿纳米晶体表现出自由和自陷激子双色光致发光的共存。飞秒瞬态吸收光谱可以证实双钙钛矿纳米晶在激发态下产生了比较明显的结构变形。我们推断这会导致激发和发射跃迁偶极子的大偏差，从而导致大的光致发光各向异性。最重要的是，我们首次观察到自由激子发射和自陷激子发射都是高度各向异性的，与卤化铅钙钛矿相当甚至更好。这项研究为探索更多的可能性和实际应用铺平了道路。

更新日期：2022-12-29

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