Ruddlesden–Popper Perovskite Alloys: Continuous and Discontinuous Tuning of the Electronic Structure
Ruddlesden–Popper Perovskite Alloys: Continuous and Discontinuous Tuning of the Electronic Structure
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DOI：
10.1021/acs.jpcc.3c01294
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发表时间：
2023-05
期刊：
影响因子：
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通讯作者：
Kameron R. Hansen;Blake Romrell;C. McClure;Michele Eggleston;Alex Berzansky;Jeffrey Wayjer Lin;Kelsey Garden;Luisa Whittaker‐Brooks;J. Colton
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文献类型：
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作者：
Kameron R. Hansen;Blake Romrell;C. McClure;Michele Eggleston;Alex Berzansky;Jeffrey Wayjer Lin;Kelsey Garden;Luisa Whittaker‐Brooks;J. Colton
将混合比例的元素合金化到卤化物钙钛矿（HP）结构中已被证明是调整这些材料的结构和电子性质以用于光伏和其他光电应用的有效方法。然而，用于表征HP合金的标准光谱，如吸收和光致发光，在检测结构内的无序和相分离的能力方面受到限制。在这里，我们在更大程度上通过使用电吸收光谱研究薄膜与混合金属（铅锡）和混合卤化物（溴氯和溴-I）组合物的2D HP合金的这些特性。在2D HP中的带边状态的大的光谱分离允许我们检测在Pb-Sn和Br-I合金内的元素富集域的共存。与此同时，我们发现，Br-Cl合金表现出更清晰的光谱特征和更均匀的电吸收响应指示的有序结构，虽然仍然不像他们的纯Br和Cl对应的有序。Br-Cl系列（PEA 2 PbBrxCl 4-x）的带隙能量可以通过Br：Cl比在3.425和4.13 eV之间连续调谐，而激子结合能可以在349到487 meV之间调谐。
Alloying mixed ratios of elements into the halide perovskite (HP) structure has proven to be an effective method of tuning these materials’ structural and electronic properties for photovoltaic and other optoelectronic applications. However, the standard spectroscopies used to characterize HP alloys such as absorption and photoluminescence are limited in their ability to detect disorder and phase segregation within the structure. Here, we characterize these properties in 2D HP alloys to a greater degree by using electroabsorption spectroscopy to study thin films with mixed-metal (Pb–Sn) and mixed-halide (Br–Cl and Br–I) compositions. The large spectral separation of band-edge states in 2D HPs allow us to detect a coexistence of elemental-rich domains within the Pb–Sn and Br–I alloys. Meanwhile, we find that the Br–Cl alloys exhibit sharper spectral features and a more uniform electroabsorption response indicative of an ordered structure, albeit still not as ordered as their pure Br and Cl counterparts. The band gap energies of the Br–Cl series (PEA2PbBrxCl4 –x) can be continuously tuned between 3.425 and 4.13 eV via the Br:Cl ratio, while the exciton binding energies can be tuned from 349 to 487 meV.