Construction of back-heterojunction crystalline silicon solar cells using Fermi-level-adjusted MXene by CuCl2

Improving the performance-to-cost ratio is innate drive for the development of photovoltaic community including research and commercialization. Among them, developing advanced solar cells with a simple device configuration but high performance is the mostly critical factor. Herein, we focus on crystalline silicon (c-Si) solar cells and attempt to develop a back-heterojunction device simply constructed by drop-casting Ti3C2Tx MXene ethanol suspension onto the backside of an n-type c-Si wafer. Thanks to the avoiding of light shading and rational adjustment of the Fermi level of the MXene by CuCl2, an impressive power conversion efficiency of 12.0 % can be achieved for the preliminary demonstration device without any further optimizations. In addition, device performance exhibits good stability in the ambient environment. [Display omitted] •A back-heterojunction solar cell is facilely made by dropping MXene on c-Si.•The adjusted Fermi level and improved performance are realized by CuCl2 treatment to MXene.•One of the highest efficiencies is reported for the corresponding devices.