Long-Term Stability of Perovskite Solar Cells under Different Growth Conditions: A Defect-Controlled Water Diffusion Mechanism.

Understanding the water-infiltration process is crucial for improving the long-term stability of perovskite solar cells (PSCs). Although many attempts have been made in this regard, the role of growth condition in PSC synthesis, which has been observed experimentally to be essential for the stability of PSCs, remains elusive. Using first-principles tools, we demonstrate that the growth condition strongly controls the water-infiltration process of PSCs by dictating the formation of point defects on PSC surfaces. The resulting point defects are found to alter both the rate and the pathways of the water-infiltration process substantially. Our work builds a new scenario for understanding the relation between the PSC decomposition mechanism and its preparation methods; it not only sheds new insights for decrypting experimental phenomenon, but also provides important guidance for future preparation of PSCs with improved water resistance.