Conductive MOF Engineering for Carbon‐Based Perovskite Solar Cells With High Efficiency, Stability, and Lead Leakage Mitigation

ABSTRACT Carbon‐electrode perovskite solar cells without hole transport layers (HTL‐free C‐PSCs) offer simple fabrication, low cost, and good environmental compatibility in photovoltaics. However, interfacial energy mismatch and severe non‐radiative recombination have long hindered their efficiency improvement. Here, we report a conductive metal‐organic framework (MOF) engineering strategy to improve performance of HTL‐free C‐PSCs by modifying the interface between the perovskite layer and the carbon electrode. A strong electron acceptor, 7,7,8,8‐tetracyanoquinodimethane (TCNQ), is incorporated within Cu 3 BTC 2 nanopores to form an intermolecular π–π conjugated network, turning the poorly conductive MOF into a functional layer that enables both defect passivation and efficient charge extraction. Abundant –COOH and –C≡N groups coordinate with uncoordinated Pb 2+ and I − , effectively passivating surface defects, reducing trap density, and suppressing non‐radiative recombination. Furthermore, by virtue of the improved energy‐level alignment at the perovskite–carbon interface and the reduced hole extraction barrier, this modifier significantly enhances charge separation and transport, thereby enabling the devices to achieve a high‐power conversion efficiency of 19.06%. HTL‐free C‐PSCs modified with TCNQ@Cu 3 BTC 2 show excellent long‐term stability, retaining 90.2% of initial efficiency after 1000 h in air without encapsulation and 91.6% after 1200 h of continuous illumination.