Multifunctional MXene for Thermal Management in Perovskite Solar Cells

Perovskite solar cells (PSCs) have emerged as promising photovoltaic technologies owing to their remarkable power conversion efficiency (PCE). However, heat accumulation under continuous illumination remains a critical bottleneck, severely affecting device stability and long-term operational performance. Herein, we present a multifunctional strategy by incorporating highly thermally conductive Ti₃C₂T_X MXene nanosheets into the perovskite layer to simultaneously enhance thermal management and optoelectronic properties. The Ti₃C₂T_X nanosheets, embedded at perovskite grain boundaries, construct efficient thermal conduction pathways, significantly improving the thermal conductivity and diffusivity of the film. This leads to a notable reduction in the device's steady-state operating temperature from 42.96 to 39.97 °C under 100 mW cm^-2 illumination, thereby alleviating heat-induced performance degradation. Beyond thermal regulation, Ti₃C₂T_X, with high conductivity and negatively charged surface terminations, also serves as an effective defect passivation agent, reducing trap-assisted recombination, while simultaneously facilitating charge extraction and transport by optimizing interfacial energy alignment. As a result, the Ti₃C₂T_X-modified PSC achieve a champion PCE of 25.13% and exhibit outstanding thermal stability, retaining 80% of the initial PCE after 500 h of thermal aging at 85 °C and 30 ± 5% relative humidity. (In contrast, control PSC retain only 58% after 200 h.) Moreover, under continuous maximum power point tracking in N₂ atmosphere, Ti₃C₂T_X-modified PSC retained 70% of the initial PCE after 500 h, whereas the control PSC drop sharply to 20%. These findings highlight the synergistic role of Ti₃C₂T_X in thermal management and optoelectronic performance, paving the way for the development of high-efficiency and heat-resistant perovskite photovoltaics.