Solution-processed Silicon/Ti₃C₂T_x MXene Schottky Junction Solar Cells

Crystalline silicon(c-Si)solar cells have been always dominating the photovoltaic market by over 90%due to its relatively high performance,excellent stability,matured fabrication technology and abundant raw materials.Although their price has been substantially cut down benefitting from the guidance of photovoltaics policy and the improvement of key technologies in these years,large-scale commercial deployment still necessitates further improvement of the performance-to-cost ratio for c-Si solar cells.In the process of exploring low-cost and high-efficiency solar cells,silicon(Si)-based Schottky junction/heterojunction solar cells having exhibited the potential to deliver a competitive power conversion efficiency(PCE)have attracted increasing attention in recent years.Previous studies have shown that PEDOT:PSS,CNTs,graphene and metal oxides prepared by low-cost methods can form good Schottky junction/heterojunction with c-Si,which play an important role in the preparation of high performance-to-cost ratio solar cells.In this study,we demonstrate novel solar cells for the Ti₃C₂T_x MXene/n-Si fabricated with the low-temperature-solution method,and explore the research schemes to improve the performance of Ti₃C₂T_x MXene/n-Si Schottky junction solar cells.The work in this paper mainly includes the following aspects:(1)A novel photovoltaic cell based on the Ti₃C₂T_x MXene/n-Si Schottky junction is developed by a simple solution-processed method of drop-casting the Ti₃C₂T_x MXene ethanol suspension onto the surface of n-Si wafers and the subsequent natural drying in air.The demonstration device delivers a PCE of 5.70%under AM 1.5G illumination.The PCE can be increased because of the improved heterojunction interface and 2D materials properties.After treating the MXene layer with the SnCl₂ solution,an improved PCE to 6.95%can be achieved because of the reduced light reflection,improved quality of junction and electrical contact,as well as the increased carrier lifetime/suppressed carrier recombination.Given the facile preparation and huge potential for the performance improvement,this work is believed to provide a valuable exploration of developing novel solar cells.(2)A facile scheme of adjusting the Ti₃C₂T_x MXene's electrical property by the solution-processed SnCl₄ treatment is reported to realize the performance improvement of the n-Si/MXene Schottky junction solar cells.We found that the optimal SnCl₄treatment can increase the electrical conductivity of the MXene layer,reduce the defects at the interface of Si and MXene and enhance the operation stability of the devices.Benefitting from the good compatibility with the micrometer-scale texture,the notable PCE 9.23%which is much higher than 4.64%for the planar Si/MXene device without the SnCl₄ treatment,is delivered by pyramid-textured n-Si/MXene device with the optimal SnCl₄ treatment.In addition,the enhanced operation stability with?88%of its initial PCE,much higher than?67%for the control device without the SnCl₄ treatment,both after storage in air for 30 days,is obtained by the SnCl₄-treated pyramid-textured n-Si/MXene device.