Structure-Dependent Photoluminescence in Low-Dimensional Ethylammonium, Propylammonium, and Butylammonium Lead Iodide Perovskites
Structure-Dependent Photoluminescence in Low-Dimensional Ethylammonium, Propylammonium, and Butylammonium Lead Iodide Perovskites
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DOI：
10.1021/acsami.9b17881
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发表时间：
2020-01-29
影响因子：
9.5
通讯作者：
Ahn, Hyeyoung
中科院分区：
文献类型：
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作者：
Lin, Chang-Wei;Liu, Fangzhou;Ahn, Hyeyoung
杂化有机-无机钙钛矿作为下一代光伏和发光器件材料引起了广泛关注。然而，它们的环境不稳定问题仍然是实际应用的最大挑战。最近出现的具有 Ruddlesden-Popper 结构的二维 (2D) 钙钛矿可以极大地改善稳定性和老化问题。此外，这些天然量子阱结构中激子的强限制导致可见光谱范围内独特且窄的光发射，从而能够开发光谱可调光源。除了强的准单色发射之外，一些由特定有机阳离子和无机层结构组成的二维钙钛矿还发出明显的宽带发射。在此，我们报告了由三种最短的烷基铵间隔基——单乙基铵（EA）、正丙基铵（PA）和正丁基铵（BA）组成的低维钙钛矿的发光特性和降解。虽然 (BA)(2)PbI4 已知可形成良好取向的二维薄膜，该薄膜由由 BA 阳离子双层分隔的共享角的 PbI6 八面体层组成，但具有较短烷基链的 EA 往往会形成其他类型的低维结构。然而，与3D对应物甲基碘化铅(MAPbI(3))钙钛矿相比，所制备的新鲜EAPbI(3)、(PA)(2)PbI4和(BA)(2)PbI4的光学吸收边明显蓝移至2.4-2.5 eV，并且它们都发射窄激子光致发光。此外，通过仔细优化沉积条件，我们实现了 (PA)(2)PbI4 的主要二维结构。然而，与 (BA)(2)PbI4 不同，暴露于周围环境后，(PA)(2)PbI4 很容易转变为不同的晶体结构，表现出大约 500 至 800 nm 的显着宽带光，并且随着结构转变的进行，强度逐渐增加。
Hybrid organic-inorganic perovskites have attracted great attention as the next generation materials for photovoltaic and light-emitting devices. However, their environment instability issue remains as the largest challenge for practical applications. Recently emerging two-dimensional (2D) perovskites with Ruddlesden-Popper structures are found to greatly improve the stability and aging problems. Furthermore, strong confinement of excitons in these natural quantum-well structures results in the distinct and narrow light emission in the visible spectral range, enabling the development of spectrally tunable light sources. Besides the strong quasi-monochromatic emission, some 2D perovskites composed of the specific organic cations and inorganic layer structures emit a pronounced broadband emission. Herein, we report the light-emitting properties and the degradation of low-dimensional perovskites consisting of the three shortest alkylammonium spacers, mono-ethylammonium (EA), n-propylammonium (PA), and n-butylammonium (BA). While (BA)(2)PbI4 is known to form well-oriented 2D thin films consisting of layers of corner-sharing PbI6 octahedra separated by a bilayer of BA cations, EA with shorter alkyl chains tends to form other types of lower-dimensional structures. Nevertheless, optical absorption edges of asprepared fresh EAPbI(3), (PA)(2)PbI4, and (BA)(2)PbI4 are obviously blue-shifted to 2.4-2.5 eV compared to their 3D counterpart, methylammonium lead iodide (MAPbI(3)) perovskite, and they all emit narrow excitonic photoluminescence. Furthermore, by carefully optimizing deposition conditions, we have achieved a predominantly 2D structure for (PA)(2)PbI4. However, unlike (BA)(2)PbI4, upon exposure to ambient environment, (PA)(2)PbI4 readily transforms to a different crystal structure, exhibiting a prominently broadband light from similar to 500 to 800 nm and a gradual increase in intensity as structural transformation proceeds.