Mechanistic origins of excitonic properties in 2D perovskites: Implications for exciton engineering
Mechanistic origins of excitonic properties in 2D perovskites: Implications for exciton engineering
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DOI：
10.1016/j.matt.2023.07.004
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发表时间：
2023-10-04
期刊：
影响因子：
18.9
通讯作者：
Whittaker-Brooks, Luisa
中科院分区：
文献类型：
--
作者：
Hansen, Kameron R.;Wong, Cindy Y.;Whittaker-Brooks, Luisa
随着2D卤化物钙钛矿（HP）领域的成熟，用于测量重要性质（例如带隙（Eg）和激子结合能（Eb））的最新技术继续产生不一致的值。在这里，我们通过直接测量31个独特的HP结构的Eg和Eb来解决这个长期存在的问题。的Eb值低于在以前的文献报道，低于预期的标准理论，假设激子被筛选的光频介电常数。这些低的Eb值被证明是独特的屏蔽效应，如超晶格屏蔽和声子屏蔽的后果。我们发现了一个惊人的强相关性Eb和Eg和提供设计原则，先验调整Eg和Eb的最佳值。因此，这项工作为低维半导体的Eg-Eb工程提供了蓝图，作为简单带隙工程的更有用的替代品。
As the field of 2D halide perovskites (HPs) matures, state-of-the-art techniques to measure important properties, such as the band gap (Eg) and exciton binding energy (Eb), continue to produce inconsis-tent values. Here, we tackle this long-standing problem by obtaining direct measurements of Eg and Eb for 31 unique HP structures. The Eb values are lower than in previous literature reports and lower than expected from standard theory that assumes excitons are screened by optical-frequency dielectric constants. These low Eb values are shown to be a consequence of unique screening effects, such as superlattice screening and phonon screening. We find a strikingly strong correlation between Eb and Eg and provide design principles to a priori tune Eg and Eb to their optimal values. As such, this work offers a blueprint for Eg-Eb engineering of low -dimen-sional semiconductors as an even more useful replacement for sim-ply band-gap engineering.