Tunable photoelectronic properties of hydrogenated-silicene/halogenated-silicene superlattices for water splitting
Hao Chen, Pinglan Yan, Jin Li, Chaoyu He, Tao Ouyang, Chunxiao Zhang, Chao Tang, Jianxin Zhong
Abstract
We propose a novel two-dimensional (2D) lateral superlattice based on silicene alternately saturated by hydrogen and halogen atoms, named as hydrogenated-silicene/halogenated-silicene superlattices (SHSXSLs, X = F, Cl, Br, and I). Employing ab initio electronic calculations, we systematically investigate the structural, electronic, and optical properties of SHSXSLs. Our results show that these superlattices are much stable than silicene as saturating the dangling bonds and the bandgap and carrier effective mass of superlattices can be modulated by the width of components due to the confinement and interfacial effects. By calculating the band alignment, it is found that all superlattices exhibit the type I alignment. Specifically, SHSCl,BrSLs have very small valence band offset and large conduction band offset, which can separate electrons and holes in these systems. Furthermore, the band edge positions of SHSCl,BrSLs satisfy the redox potential of the water splitting and SHSCl,BrSLs exhibit strong absorption in the visible region, suggesting that these superlattices are promising materials for photovoltaics and photocatalytics. This new type of superlattice structure can be applied to other 2D materials with strong activity to enhance the stability and modulate the properties effectively.