SnCl₄-Treated Ti₃C₂T_x MXene Nanosheets for Schottky Junction Solar Cells with Improved Performance

Ti3C2Tx MXene has recently attracted increasing attention in optoelectronics because of its good optical and electrical properties. Herein, we report a facile scheme of adjusting its electrical property by solution-processed SnCl4 treatment to realize the significantly improved performance of an n-type silicon (n-Si)/MXene Schottky junction solar cell prepared just by drop-casting the ethanol suspension of Ti3C2Tx MXene nanosheets onto the n-Si surface and subsequent natural drying. It is found that the optimal treatment by SnCl4 increases the electrical conductivity of the MXene layer and reduces the defects at the interface of Si and MXene. Thanks to its good compatibility with the micrometer-scale texture, the demonstration device of the pyramid-textured n-Si/SnCl4-treated MXene nanosheets delivers a notable power conversion efficiency (PCE) of 9.3%, which is much higher than 4.7 and 4.8% for the pyramid-textured n-Si/MXene nanosheet device and the planar Si/MXene nanosheet device, respectively, both without SnCl4 treatment. Moreover, the SnCl4-treated pyramid-textured n-Si/MXene nanosheet device exhibits significantly improved operation stability with ∼88% of its initial PCE, much higher than ∼67% for the control device without SnCl4 treatment, both after storage in air for 30 days.