Surface and Interface Engineering of MXenes Enables TCO‐Free Silicon Heterojunction Solar Cells
Wei Li, Yu Yan, Taiqiang Wang, Hongyu Dun, Qianfeng Gao, Mingyu Yang, Maobin Zhang, Junming Xue, Daming Chen, Keng Siew Chan, Xiaodan Zhang, Qian Huang, Guofu HouABSTRACT
Indium tin oxide (ITO) remains the conventional transparent electrode in silicon heterojunction (SHJ) solar cells, yet its reliance on scarce indium raises concerns over cost and scalability. MXenes are solution‐processable and indium‐free, but have so far been confined to electrode roles rather than functioning as primary transparent electrodes that fully displace ITO, particularly on the optically demanding front side. Here we report a fully TCO‐free SHJ solar cell in which surface‐termination engineering enables Ti 3 C 2 T x MXene to act as the transparent electrode on both sides. Hydroxyl‐rich and oxygen‐terminated Ti 3 C 2 T x were synthesized for the front and rear contacts, respectively, with their work functions tuned for the required energy‐level alignment. A front MgF 2 antireflection coating and a rear Ti 3 C 2 T x /AgNW hybrid electrode offset the intrinsic optical losses and inter‐flake resistance of the MXene films. The optimized device reached an efficiency of 23.14%, comparable to a co‐processed, industrially relevant ITO reference. The performance was highly reproducible, with a relative standard deviation in efficiency below 1%, and the devices retained on average over 95% of their initial efficiency after 304 days of storage. These findings establish termination‐engineered MXenes as a credible transparent‐electrode option for next‐generation, indium‐free SHJ photovoltaics.