Wang, YanhaoGuo, ZhaoyangLi, YongchangBlack, Lachlan E.MacDonald, Daniel H.Bao, ShaojuanWang, JileiZhang, YongzheZhang, Shan TingLi, Dongdong2025-05-232025-05-232050-7488ORCID:/0000-0001-5792-7630/work/183735682http://www.scopus.com/inward/record.url?scp=85206445981&partnerID=8YFLogxKhttps://hdl.handle.net/1885/733750866Carrier-selective passivating contacts in crystalline silicon (c-Si) solar cells have expanded from doped silicon films to non-silicon wide-bandgap materials to reduce parasitic absorption and production costs. Titanium oxide (TiOx) has emerged as one of the most promising materials and has achieved high performance in c-Si solar cells. In this work, TiOx is explored as a passivation interlayer in hole-selective contacts rather than conventional electron-selective contacts. Theoretical calculations and experimental results demonstrate that negative charges and shallow states in TiOx, derived from oxygen vacancies (VO), enhance surface passivation and assist hole tunneling, respectively. As a strategy to modulate VO, forming gas annealing is performed to further improve hole selectivity. By incorporating the TiOx passivation interlayer into MoOx-based c-Si solar cells, we achieve an improved efficiency and stability of the device, with the highest efficiency of 21.28%. This work advances the understanding of TiOx as a promising material to enhance hole selectivity for c-Si solar cells.This work was supported by the National Key R&D Program of China (2022YFB4200204) and the Australian Renewable Energy Agency (ARENA) through the Australian Centre for Advanced Photovoltaics (ACAP). Y. W. acknowledges the financial support from the China Scholarship Council (202304910405). The authors would like to thank Soft Matter Nanofab of ShanghaiTech University and ShanghaiTech Material and Device Lab (SMDL) for the assistance in ALD-TiOx deposition and ellipsometry characterization. This work was supported by the National Key R&D Program of China (2022YFB4200204) and the Australian Renewable Energy Agency (ARENA) through the Australian Centre for Advanced Photovoltaics (ACAP). Y. W. acknowledges the financial support from the China Scholarship Council (202304910405). The authors would like to thank Soft Matter Nanofab of ShanghaiTech University and ShanghaiTech Material and Device Lab (SMDL) for the assistance in ALD-TiO deposition and ellipsometry characterization. x10en© 2024 The Author(s)2024-10-0710.1039/d4ta05538a85206445981