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arXiv 1910.04583physics.app-phcond-mat.mtrl-sci
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钙钛矿太阳能电池深能级瞬态谱的改进评估揭示了离子缺陷分布

Improved evaluation of deep-level transient spectroscopy on perovskite solar cells reveals ionic defect distribution

Sebastian Reichert, Jens Flemming, Qingzhi An, Yana Vaynzof, Jan-Frederik Pietschmann, Carsten Deibel

发表信息：
Phys. Rev. Applied 13, 034018 (2020)
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摘要：

未来开发高效稳定的金属卤化物钙钛矿太阳能电池的关键挑战之一与这些材料中离子的迁移有关。移动离子已被链接到观察的电流-电压特性的滞后，显示降低器件的稳定性对退化和作为复合中心内的有源层的带隙。在文献中，人们发现对于看似相似的钙钛矿材料，广泛传播的报道的离子缺陷参数（例如活化能），使得难以识别这些物质的性质。在这项工作中，我们进行了依赖于温度的深能级瞬态光谱（DLTS）的测量甲基铵碘化铅钙钛矿太阳能电池，并开发了一个扩展的正则化算法反演拉普拉斯变换。我们的研究结果表明，移动离子形成的发射率分布（即扩散常数的分布）为每个观察到的离子物种，这可能是负责在以前报道的缺陷参数的差异。重要的是，不同的DLTS模式，如光学和电流DLTS产生相同的缺陷分布。最后，我们的结果与传统的boxcar DLTS和阻抗谱（IS）的比较验证了我们的评估算法。

英文摘要：

One of the key challenges for future development of efficient and stable metal halide perovskite solar cells is related to the migration of ions in these materials. Mobile ions have been linked to the observation of hysteresis in the current--voltage characteristics, shown to reduce device stability against degradation and act as recombination centers within the band gap of the active layer. In the literature one finds a broad spread of reported ionic defect parameters (e.g. activation energies) for seemingly similar perovskite materials, rendering the identification of the nature of these species difficult. In this work, we performed temperature dependent deep-level transient spectroscopy (DLTS) measurements on methylammonium lead iodide perovskite solar cells and developed a extended regularization algorithm for inverting the Laplace transform. Our results indicate that mobile ions form a distribution of emission rates (i.e. a distribution of diffusion constants) for each observed ionic species, which may be responsible for the differences in the previously reported defect parameters. Importantly, different DLTS modes such as optical and current DLTS yield the same defect distributions. Finally the comparison of our results with conventional boxcar DLTS and impedance spectroscopy (IS) verifies our evaluation algorithm.

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