Interfacial Regulation with Fluorinated Molecules for Inverted Sequential Perovskite Solar Cells

This is the authors' abstract. We don't add key points for this paper.

The two-step-based inverted perovskite solar cells (IPSCs) represent a key technical approach for realizing large-area modules and perovskite-silicon tandem solar cells. However, the substantial energy level mismatch between NiO X and the perovskite layer, as well as the defect-dense surface of NiO X, continue to hinder the performance enhancement of IPSCs. In this work, an interface modification material of 4-(trifluoromethyl)benzyl alcohol (4-TFBA) was introduced between the NiO X and perovskite layers. The hydroxyl group of 4-TFBA can effectively coordinate with Ni 3+ on the NiO X surface, passivating surface defects, while the trifluoromethyl (−CF 3 ) group forms strong interactions with the perovskite layer, including hydrogen bonding with formamidinium cations (FA + ) and coordination with Pb 2+ . This dual functionality not only optimizes the energy level alignment between NiO X and perovskite but also promotes favorable nucleation and crystallization of the perovskite layer, thereby enhancing interfacial charge carrier mobility and improving charge extraction efficiency in the perovskite film. As a result, the power conversion efficiency (PCE) of IPSCs fabricated via the two-step method increased to 20.4% after modification with 4-TFBA, and the fill factor (FF) increased to 80.27%. Fluorinated molecules provide a robust strategy for achieving high-performance inverted perovskite solar cells via the two-step preparation.