Degradation of Methylammonium Lead Iodide Perovskite Structures through Light and Electron Beam Driven Ion Migration.
Degradation of Methylammonium Lead Iodide Perovskite Structures through Light and Electron Beam Driven Ion Migration.
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DOI：
10.1021/acs.jpclett.5b02828
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发表时间：
2016-02-04
期刊：
影响因子：
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通讯作者：
Roeffaers M
中科院分区：
文献类型：
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作者：
Yuan H;Debroye E;Janssen K;Naiki H;Steuwe C;Lu G;Moris M;Orgiu E;Uji-I H;De Schryver F;Samorì P;Hofkens J;Roeffaers M
有机金属卤化物钙钛矿显示出具有成本效益的应用在光致发光的有前途的功能。材料的不稳定性仍然是广泛应用的主要障碍，因为对降解途径知之甚少。在这里，我们第一次在钙钛矿上同时应用发光和电子显微镜，使我们能够监测钙钛矿降解后的原位形态演变和光学性质。有趣的是，钙钛矿样品的形态，光致发光（PL），和阴极射线发光的演变不同的降解驱动的电子束（电子束）或光。由扫描电子束产生的横向电流导致PL的急剧变化，并沿着薄膜减薄连续调谐能带隙。与此相反，光诱导降解的结果在材料分解为散射颗粒，并显示出很小的PL光谱位移。降解的差异可以归因于驱动离子迁移的不同电流。此外，溶液处理的钙钛矿立方体显示稳定性的异质性，这可能与结晶度和形态有关。我们的研究结果揭示了离子迁移在钙钛矿降解中的重要作用，并提供了通过减少离子迁移同时改善形态和结晶度来合理提高钙钛矿材料稳定性的潜在途径。值得注意的是，即使是中等的电子束电流（86 pA）和加速电压（10 kV）也容易引起显著的钙钛矿降解并改变其光学性质。因此，必须注意，同时使用扫描电子显微镜或透射电子显微镜技术表征这些材料。
Organometal halide perovskites show promising features for cost-effective application in photovoltaics. The material instability remains a major obstacle to broad application because of the poorly understood degradation pathways. Here, we apply simultaneous luminescence and electron microscopy on perovskites for the first time, allowing us to monitor in situ morphology evolution and optical properties upon perovskite degradation. Interestingly, morphology, photoluminescence (PL), and cathodoluminescence of perovskite samples evolve differently upon degradation driven by electron beam (e-beam) or by light. A transversal electric current generated by a scanning electron beam leads to dramatic changes in PL and tunes the energy band gaps continuously alongside film thinning. In contrast, light-induced degradation results in material decomposition to scattered particles and shows little PL spectral shifts. The differences in degradation can be ascribed to different electric currents that drive ion migration. Moreover, solution-processed perovskite cuboids show heterogeneity in stability which is likely related to crystallinity and morphology. Our results reveal the essential role of ion migration in perovskite degradation and provide potential avenues to rationally enhance the stability of perovskite materials by reducing ion migration while improving morphology and crystallinity. It is worth noting that even moderate e-beam currents (86 pA) and acceleration voltages (10 kV) readily induce significant perovskite degradation and alter their optical properties. Therefore, attention has to be paid while characterizing such materials using scanning electron microscopy or transmission electron microscopy techniques.