Surface Reconstruction for Efficient NiO x -Based Inverted Perovskite Solar Cells.

Functional agents are verified to efficiently enhance device performance of perovskite solar cells (PSCs) through surface engineering. However, the influence of intrinsic characteristics of molecules on final device performance is overlooked. Here, a surface reconstruction strategy is developed to enhance the efficiency of inverted PSCs by mitigating the adverse effects of lead chelation (LC) molecules. Bathocuproine (BCP) is chosen as the representative of LC molecules for its easy accessibility and outstanding optoelectronic properties. During this strategy, BCP molecules on perovskite surface are first dissolved in solvents and then captured specially by undercoordinated Pb 2+ ions, preventing adverse n-type doping by the molecules themselves. In this case, the BCP molecule exhibits outstanding passivation effect on perovskite surface, which leads to an obviously increased open-circuit voltage (V OC ). Therefore, a record power conversion efficiency of 25.64% for NiO x -based inverted PSCs is achieved, maintaining over 80% of initial efficiency after exposure to ambient condition for ≈1500 h.