High-Efficiency Sb2(S,Se)3 Solar Cells with New Hole Transport Layer-Free Back Architecture via 2D Titanium-Carbide Mxene

MXene, a class of 2D materials of metal carbide or nitride, has attracted a lot of attention recently due to its excellent optical and electrical properties. In this work, titanium-carbide MXene (Ti3C2Tx) is introduced as a back electrode in Sb-2(S,Se)(3) thin-film solar cells (FTO/CdS/Sb-2(S,Se)(3)/MXene) for the first time, which displaces traditional carbon (C) and gold (Au) electrodes entirely. Impressively, thanks to its high conductivity, mild reflectivity, and flexible flake architecture, the MXene-based device performance outperforms typical C and Au electrodes by 153% and 77%, respectively. Specifically, the tunable work function of MXene and a beneficial Sb-O bond formed between Sb-2(S,Se)(3) and MXene efficiently suppress the recombination and enhance charge transport by enjoying the unique merit of the rich terminal groups of MXene. As a result, the best efficiency of 8.29% of MXene-based Sb-2(S,Se)(3) solar device is achieved, which represents the highest performance of noble metal and/or hole transport layer-free derived Sb-2(S,Se)(3) solar cells to date. This result has revealed that MXene is a feasible material to substitute the back electrode in Sb-based solar cells to reach high efficiency, low cost, and high stability.

Automated summary

In this study, MXene is introduced as a back electrode in Sb-based solar cells for the first time, replacing traditional carbon and gold electrodes and achieving significantly higher performance. The beneficial interaction between MXene and Sb-2(S,Se)(3) suppresses recombination and enhances charge transport, leading to the highest efficiency achieved by noble metal and/or hole transport layer-free derived Sb-2(S,Se)(3) solar cells to date.