Electrodeposited TiO₂ Film with Mossy Nanostructure for Efficient Compact Layer in Scaffold‐Type Perovskite Solar Cell

A quality compact layer (CL) with a thin and pinhole‐free structure is essential for an efficient perovskite solar cell (PSC). This study offers a new perspective regarding a criterion of a quality CL, namely three‐dimensional interfacial contact. In an examination of the deposition mechanisms, film morphologies, and optical and electronic properties of CLs fabricated using different methods, an electrodeposited (ED) TiO 2 CL outperformed other TiO 2 CLs. This is not only because of its ultrathin, fully covered morphology but also because of its mossy structure, which provides high shunt resistance and low ohmic resistance in ED‐TiO 2 ‐based PSCs. In addition, our results confirm that in scaffold‐type PSCs, the CL provides a charge extraction function in addition to the mesoporous scaffold, which is designed as the main electron transporting layer.