A Composite Interlayer Reconciling Mechanical and Electrical Stability in Perovskite Solar Cells

Abstract

ABSTRACT Interfacial instability of n ‐type contacts remains a key barrier to the commercialization of perovskite solar cells (PSCs), as coupled lattice stress and ion migration rapidly deteriorate electronic order and structural integrity. Here, we report a fully solution‐processed n ‐type interfacial architecture that unifies mechanical compliance, electronic stabilization, and thickness‐insensitive operation. A thermally in situ self‐crosslinked bathocuproine derivative (c‐BCP) is integrated with a π‐conjugated n ‐type conductive ink (PBFDO:PEOx) to form a mechanically continuous yet electronically selective junction that remains effective across thicknesses approaching 60 nm. This composite interlayer effectively redistributes interfacial stress, suppresses halide migration, and minimizes defect‐assisted nonradiative recombination. By coupling elastic energy dissipation with directional charge transport, the design resolves the long‐standing trade‐off between interfacial robustness and carrier extraction in n ‐type contacts. Devices incorporating this interlayer deliver a champion efficiency of 26.37% and retain >92% of their initial performance after 1000 h of continuous illumination under thermal stress. These results establish a generalizable and manufacturing‐ready framework for thick, solution‐processable n ‐type contacts, enabling intrinsically durable and high‐efficiency perovskite optoelectronics.