Humidity‐Induced Degradation via Grain Boundaries of HC(NH2)2PbI3 Planar Perovskite Solar Cells |
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| Authors: | Jae Sung Yun Jincheol Kim Trevor Young Robert J. Patterson Dohyung Kim Jan Seidel Sean Lim Martin A. Green Shujuan Huang Anita Ho‐Baillie |
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| Affiliation: | 1. Australian Centre for Advanced Photovoltaics (ACAP), School of Photovoltaic and Renewable and Engineering, University of New South Wales, Sydney, Australia;2. School of Materials Science and Engineering, University of New South Wales, Sydney, Australia;3. Electron Microscopy Unit, University of New South Wales, Sydney, Australia |
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| Abstract: | The sensitivity of organic–inorganic perovskites to environmental factors remains a major barrier for these materials to become commercially viable for photovoltaic applications. In this work, the degradation of formamidinium lead iodide (FAPbI3) perovskite in a moist environment is systematically investigated. It is shown that the level of relative humidity (RH) is important for the onset of degradation processes. Below 30% RH, the black phase of the FAPbI3 perovskite shows excellent phase stability over 90 d. Once the RH reaches 50%, degradation of the FAPbI3 perovskite occurs rapidly. Results from a Kelvin probe force microscopy study reveal that the formation of nonperovskite phases initiates at the grain boundaries and the phase transition proceeds toward the grain interiors. Also, ion migration along the grain boundaries is greatly enhanced upon degradation. A post‐thermal treatment (PTT) that removes chemical residues at the grain boundaries which effectively slows the degradation process is developed. Finally, it is demonstrated that the PTT process improves the performance and stability of the final device. |
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| Keywords: | degradation formamidinium humidity moisture stability perovskite solar cells |
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