Omnibearing Molecular-Locking of Perovskite Lattice Enables High-Performance Perovskite Solar Cells with Efficiency over 26%

Solution-processed polycrystalline perovskite films are favorable for low-cost manufacturing of perovskite solar cells (PSCs). However, multiple-energy-level trap states in perovskites can trigger ionic migration and degrade device efficiency. Herein, a multidentate-anchoring strategy by introducing 6-thioguanine as an additive is employed to enable omnibearing molecular locking of the perovskite lattice. Theoretical calculations indicate that the molecular locking can increase the formation energy of multiple-energy-level defects including I vacancy, Pb vacancy, Pb interstitial, and Pb-I antisite, which can enhance the stability of PSCs. The additive can not only retard crystal growth that initiates the construction of high-crystallinity film with fewer trap states, but also up-shift energy level of perovskite that favors interfacial hole extraction. Owing to these merits, present work achieves a formamidinium lead iodide PSC that delivers a champion efficiency of 26.02%, setting a new benchmark for TiO₂-based planar PSCs, along with pronounced operational stability with almost no efficiency degradation over 400 h. This work paves a way for exploring constructive molecular configurations to simultaneously eliminate multiple-energy-level defects in perovskite for advanced photovoltaics.