Indium-Based Octahedra Coordinating Pb-I Termini for Stable Perovskites.

Wen, Yehui; Shen, Yueqi; Wang, Xingtao; Li, Biao; Zhang, Tianchi; Zhao, Dongming; Ning, Weihua; Yu, Xuegong et al. · Nat Commun · 2026

basic_science · Level V

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Abstract

Halide perovskite degradation initiates at surfaces/interfaces, where defect accumulation disrupts octahedral connectivity and triggers structural collapse. Herein, we design an indium-based octahedral motifs, i.e., (PMA)<sub>4</sub>InCl<sub>7</sub> (PIC) (PMA=phenylmethylammonium) featuring disordered octahedra and (PMA)<sub>4</sub>NaInCl<sub>8</sub> (PNIC) with ordered octahedral frameworks, as robust coordination agent to bind Pb-I termini at the surface/interface. Distinct from the isolated cluster of PIC, PNIC forms a coherent inorganic framework at Pb-I termini, enabling coherent interfacial coupling with the 3D perovskite via octahedral-level coupling between In(Na)-Cl and Pb-I units. This rigid octahedral coupling immobilizes formamidinium cations and Pb-I octahedra at the surface/interface, suppressing structural freedom. Moreover, this coupling facilitates the relaxation of interfacial structural imperfections while simultaneously establishing favorable band alignment, together governing enhanced carrier transport dynamics. As a result, the resulting perovskite solar cells deliver an efficiency of 27.29% (certified 26.84%), with the minimodules reaching 24% (certified 23.54%). Moreover, these devices demonstrate significant operational stability, retaining over 98% of their initial efficiency after 3,000 h of maximum power point tracking.