Molecularly Templated Buried Interfaces for Inverted Perovskite Solar Cells

The buried interface between self-assembled monolayers (SAMs) and perovskite absorbers critically governs charge extraction and stability in inverted perovskite solar cells, yet remains structurally mismatched and poorly controlled. Here, we report a buried-interface engineering strategy inspired by non‑covalent molecular templating, enabled by complementary triphenylamine-based molecular building blocks. A triphenylamine-based ammonium salt, 2-(4-(diphenylamino)phenyl)ethanammonium iodide (TPANI), is introduced into the perovskite precursor, while a structurally matched triphenylamine-based bisphosphonic acid SAM deposited on ITO serves as the hole-selective layer. Non-covalent interactions at the buried interface induce molecular templating and interfacial organization of TPANI, strengthening SAM/perovskite adhesion and reducing intergranular groove depth at the buried side of the perovskite film. The resulting monolithically integrated interface suppresses buried interfacial defects, improves energy-level alignment, and facilitates hole extraction. Consequently, inverted devices achieve a power conversion efficiency of 26.58% with an exceptionally high fill factor of 86.72%, together with markedly enhanced operational stability. These results demonstrate that non‑covalent molecular templating provides an effective and general strategy for engineering buried interfaces in perovskite photovoltaics.