Klotz Dino, Tumen-Ulzii Ganbaatar, Qin Chuanjiang, Matsushima Toshinori, Adachi Chihaya
International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University Fukuoka Japan
Center for Organic Photonics and Electronics Research (OPERA), Kyushu University Fukuoka Japan.
RSC Adv. 2019 Oct 17;9(57):33436-33445. doi: 10.1039/c9ra07048f. eCollection 2019 Oct 15.
The current status of electrochemical impedance spectroscopy (EIS) and related analysis on perovskite solar cells (PSC) is still unsatisfactory. The provided models are still vague and not really helpful for guiding the efforts to develop more efficient and stable devices. Due to the slow and complex dynamics of these devices, the obtained spectra need to be validated, which is hardly ever done. This study may be the first to provide fully validated impedance spectra and presents reproducible EIS time series at open circuit voltage ( ) for more than 20 hours, with a total of 140 analysed spectra. We conclude that the observed changes stem from a temporary reduction of the electronically active area of the devices, as can be deduced from the inverse behaviour of resistance and capacitance. The changes in these values are almost 100% reversible if the devices are kept in the dark for only one day, while the time constant of the high-frequency process remains unchanged throughout the whole characterization procedure. The tested devices are full PSC devices that have proven to be stable over more than 500 hours, and the non-steady impedance measurements shine a critical light on previously published EIS data. With the results of this study, it can be rationalized that the high-frequency semicircle can serve as a good indicator for ionic migration by monitoring its consequences. The results presented here are helpful to quantify ionic migration on the device level in order to derive new stability criteria and countermeasures against degradation.
钙钛矿太阳能电池（PSC）的电化学阻抗谱（EIS）及其相关分析的现状仍不尽人意。现有的模型仍然不够清晰，对于指导开发更高效、更稳定的器件并无实际帮助。由于这些器件的动力学过程缓慢且复杂，所获得的光谱需要进行验证，但这几乎从未做到过。本研究可能首次提供了经过充分验证的阻抗谱，并展示了在开路电压（ ）下超过20小时的可重复EIS时间序列，共分析了140个光谱。我们得出结论，观察到的变化源于器件电子活性面积的暂时减小，这可以从电阻和电容的反比行为推断出来。如果将器件置于黑暗中仅一天，这些值的变化几乎100%是可逆的，而高频过程的时间常数在整个表征过程中保持不变。所测试的器件是全PSC器件，已证明在超过500小时内是稳定的，非稳态阻抗测量为先前发表的EIS数据提供了关键的启示。基于本研究的结果，可以合理地认为，通过监测其结果，高频半圆可作为离子迁移的良好指标。这里呈现的结果有助于在器件层面量化离子迁移，以便得出新的稳定性标准和抗降解对策。
