Abstract
As a fundamental property of semiconductors, the band structure is crucial in the study and application of semiconductors. As a consequence, there are various band engineering methods. Here, we study the band structure engineering in two different two-dimensional semiconductors: TMDCs heterobilayers (HBLs) and hybrid layered double perovskites (HLDPs). The first part is about TMDCs HBLs. We find that The interlayer distance between MoSe2 and WSe2 layers changes from 6.6 Å to 7.7 Å with two different opposite orders, which greatly affects the band structures of the HBL system. The second part is about HLDPs. We study the band structures of PEA4AgFeCl8 and PEA4NaFeCl8. Our calculations suggest that the different contributions of Na and Ag elements to valence band maximum leads to different band gaps of PEA4AgFeCl8 and PEA4NaFeCl8.