Engineering the Recombination Layer with Ti3C2Tx MXene/IZO for Enhanced Charge Extraction in Monolithic Perovskite/Silicon Tandem Solar Cells

Recombination layer engineering is a key enabler in monolithic perovskite/silicon tandem solar cells, where charge extraction and optical management must be simultaneously optimized. In this study, we introduce a composite Ti 3 C 2 T x MXene/indium zinc oxide (IZO) interlayer as a tunable recombination layer to enhance both electrical and optical performance in two-terminal tandem architectures. The interlayers were fabricated by integrating few-layer Ti 3 C 2 T x MXene flakes into an IZO matrix, forming a conductive yet transparent network. Systematic tuning of MXene content revealed that the sample with 10 vol% (MX-10) offered a low resistivity (∼1.69 mΩ·cm), and high optical transmittance. EIS and TRPL analyses demonstrated improved charge recombination dynamics and enhanced carrier extraction. When implemented in monolithic tandems, the MX-10-based device achieved a PCE of 26.67%, outperforming the ITO-based control device (24.40%), with improved J SC and FF. Long-term stability testing over 1000 hours under continuous illumination revealed only 9.5% degradation in MX-10 devices, confirming the material's promise for practical applications. Our findings highlight the synergistic role of MXene and IZO in constructing an efficient, transparent, and stable interfacial layer for next-generation tandem photovoltaics.