• Integration of 2D transition metal carbides (TiC/WC) into FA0.85MA0.15PbI3 active layers creates conductive networks and passivates grain-boundary defects, reducing trap density from 10^16 to 10^14 cm−3.
• WC-engineered active layers deliver a champion power conversion efficiency of 24.25%, outperforming TiC-incorporated (23.74%) and pristine (22.56%) devices.
• AL@WC devices retain 86% of initial PCE after 800 h in ambient air (40% RH) under dark conditions and 81% under continuous illumination; N2 storage improves retention to 89% (dark) and 83% (illumination).
• The work establishes a scalable PSC paradigm that unifies charge extraction and stabilization, overcoming the traditional efficiency–stability tradeoff for >24% efficient photovoltaics.