Transition metal carbide-engineered active layers for high-efficiency and stable perovskite solar cell

We introduce an innovative perovskite solar cell (PSC) architecture featuring a multifunctional active layer (AL) of FA_0.85MA_0.15PbI₃ (FA: formamidine, MA: methylamine) integrated with two dimensional (2D) transition metal carbides (TiC/WC). The properties of the chemically reduced WC and TiC were thoroughly validated through structural and morphological analyses. This design significantly enhances the conventional charge-transporting properties of the AL by utilizing conductive carbide networks (conductivity (σ) > 1200 S/cm) and achieving defect passivation at grain boundaries (reducing trap density from 10¹⁶ to 10¹⁴ cm⁻³), along with providing intrinsic stability against environmental stressors. Devices constructed with the AL@WC configuration achieved a remarkable power conversion efficiency (PCE) of 24.25%, surpassing both the TiC-incorporated devices (23.74%) and the pristine AL devices (22.56%). Significantly, after 800 h in ambient air conditions (40% relative humidity), the AL@WC device retained 86% of its initial PCE under dark conditions and 81% under continuous illumination. In a nitrogen environment, dark stability measurements indicated a retention rate of 89%, while illumination stability exhibited an 83% retention for the AL@WC, affirming the enhanced protective capabilities and stability provided by the WC-integrated FA_0.85MA_0.15PbI₃ AL configuration. This work establishes a simplified and high-performance PSC paradigm by effectively uniting charge extraction and stabilization within the AL, paving the way for scalable photovoltaics exceeding 24% efficiency and operational stability.