Elucidating the Impact of Buried Interface Engineering\non Perovskite Properties and Stability in Inverted Perovskite Solar\nCells

Buried-interface\nengineering is crucial in the fabrication of perovskite\nsolar cells (PSCs) due to its effectiveness in facilitating the deposition\nof perovskite absorbers. This technique is especially significant\nin inverted PSCs (IPSCs) where the dewetting materials are normally\nused as the bottom hole transporters. Here, we investigate the impact\nof buried-interface techniques on the optical and mechanical behavior\nof perovskites and the overall stability of IPSCs. Our findings demonstrate\nthat the chemical treatment with fluorene-based conjugated polyelectrolyte\n(e.g., PFN-Br), in contrast to the physical UV-ozone method, induces\ndistinct dendrite-like patterns at the buried interface. These changes\nprofoundly impact the optical properties of the perovskite films,\nevidenced by red-shifted photoluminescence in these regions. Furthermore,\nthe dendritic morphologies are shown to affect the mechanical properties\nof the as-crystallized perovskite films, such as a reduction in Young’s\nmodulus/hardness, which in turn modulate the device performance. The\nphotovoltaic data indicate that these dendrite-like patterns are beneficial\nfor the initial efficiencies but compromise the long-term stability\nof the derived IPSCs. This study provides valuable insights into buried-interface\nengineering strategies for achieving efficient and stable IPSCs.