Perovskite solar cells are attractive because of their remarkably improved power conversion efficiency. In view of their application, however, it is important not only to increase the power conversion efficiency, but also to elucidate the deterioration mechanism. Here, we show operando direct observation of spin states in the cells using electron spin resonance, thereby investigating the operation and deterioration mechanisms from a microscopic viewpoint. By simultaneous measurements of solar cell characteristics and electron spin resonance, the spin states in the hole transport material spiro-OMeTAD are demonstrated to change in accordance with the device performance variation under operation. These variations are ascribed to the change of hole transport and to interfacial electric dipole layers. Reverse electron transfer from TiO₂ to the hole transport material layer is demonstrated under ultraviolet light irradiation, which decreases hole doping. Conducting such operando microscopic investigation will be useful to obtain further guidelines for improving the device performance and durability.

钙钛矿太阳能电池由于其功率转换效率显着提高而具有吸引力。然而，考虑到它们的应用，重要的是不仅提高功率转换效率，而且阐明劣化机理。在这里，我们展示了使用电子自旋共振直接观察细胞自旋态的操作，从而从微观角度研究了操作和劣化机理。通过同时测量太阳能电池的特性和电子自旋共振，表明空穴传输材料spiro-OMeTAD中的自旋状态会随着操作过程中器件性能的变化而变化。这些变化归因于空穴传输的变化和界面电偶极子层。TiO的反向电子转移在紫外线的照射下，对空穴传输材料层进行了与图_2相同的说明，这减少了空穴掺杂。进行这种操作显微镜研究对于获得进一步的指导以改善设备性能和耐用性将是有用的。