Pb-Rich Buried Interface Promoting Upward Unidirectional Crystallization for Efficient and Stable Carbon-Based...

Improving the crystalline quality of perovskite films is the most effective approach for constructing high-performance carbon-based perovskite solar cells (C-PSCs). In particular, highly (100)-oriented monolayer perovskite films can effectively suppress defect-induced recombination while enhancing charge transport, thereby reducing non-radiative recombination losses in C-PSCs. In this work, we propose a scalable strategy for constructing a Pb-rich modified buried interface with abundant Pb sites, which promotes perovskite nucleation and induces an upward unidirectional crystallization process, resulting in large-grained, (100)-oriented perovskite films. Moreover, the Pb-rich interface layer of Pb₁₀(PO₄)₆O exhibits better lattice matching with perovskite, significantly alleviating interfacial lattice strain at the buried interface. As a result, the fabricated C-PSCs achieved a champion efficiency of 21.56%, as well as an efficiency of 18.12% for the carbon-based mini-module (10.08 cm²), which is among the best reported efficiencies for hole transport layer-free planar C-PSCs. In addition, the maximum power point tracking of unencapsulated devices offered an outstanding T₉₀ lifetime exceeding 1000 h under the ISOS-L-1I standard protocol. These results confirm that the above strategy possesses excellent scalability and strong potential for large-area perovskite photovoltaics.