Asymmetric Cathodoluminescence Emission in CH3NH3PbI3–xBrx Perovskite Single Crystals

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• 作者：M. Ibrahim Dar ; Gwénolé Jacopin ; Mahmoud Hezam ; Neha Arora ; Shaik Mohammed Zakeeruddin ; Benoit Deveaud ; Mohammad Khaja Nazeeruddin ; Michael Grätzel
• 刊名：ACS Photonics
• 出版年：2016
• 出版时间：June 15, 2016
• 年：2016
• 卷：3
• 期：6
• 页码：947-952
• 全文大小：492K
• 年卷期：0
• ISSN：2330-4022

文摘

Probing local emission properties of organic–inorganic lead halide perovskite material can provide evidence regarding the photovoltaic performance of perovskite solar cells. Herein, cathodoluminescence, which has the potential to resolve emission characteristics in the nanoregime, has been exploited to carry out temperature-dependent studies on individual well-faceted CH₃NH₃PbI_3–xBr_x perovskite single crystals. The spatial distribution of emission recorded at 4 and 300 K reveals that the periphery of the perovskite crystals radiates predominantly, which establishes that such an unusual emission characteristic is independent of the crystallographic phase of CH₃NH₃PbI_3–xBr_x crystals. Investigation based on scanning transmission electron microscopy coupled with energy dispersive X-ray spectroscopy deduces that the asymmetric cathodoluminescence is associated with the nonhomogeneous distribution of methylammonium cations in CH₃NH₃PbI_3–xBr_x single crystals. These results emphasize the unraveling of a correlation between the composition and spectroscopic properties of perovskite crystals in the nanoregime, which eventually can influence the overall photovoltaic performance of the devices based on them.