Electronic Properties of 2D Vander Waals Heterostructures of Janus Transition Metal Dichalcogenides with WS2 Monolayer for Photovoltaic Devices: A First Principle Study
| dc.contributor.advisor | Sintayehu, Nibret (PhD) | |
| dc.contributor.author | Tsigie, Getie | |
| dc.date.accessioned | 2020-09-17T06:40:24Z | |
| dc.date.accessioned | 2023-11-28T13:24:50Z | |
| dc.date.available | 2020-09-17T06:40:24Z | |
| dc.date.available | 2023-11-28T13:24:50Z | |
| dc.date.issued | 2020-06 | |
| dc.description.abstract | Building two-dimensional (2D) heterostructure emerges novel properties, with promising applications in photovoltaic (PV) cells. By performing density functional theory (DFT) based firstprinciples calculations, electronic properties of WS2 and Janus transition-metal dichalcogenides (JTMDs) monolayers were calculated and depending on the lattice mismatch, layered 2D JTMDs/WS2 heterostructures were formed. The formation of the JTMDs/WS2 van der Waals (vdW) heterostructures have shown great potential for the design of novel electronic devices. In this study, Janus MoSSe/WS2, WSSe/WS2, and MoSTe/WS2 heterostructures were developed and their structural and electronic properties were evaluated using first principles calculations based on DFT calculations using Quantum ESPRESSO and VASP codes. It was found that the heterostructures bandgap is smaller than the Janus TMDs and WS2 monolayer. Structural relaxations were performed using generalized-gradient approximation (GGA) approaches for both the monolayers and heterostructures. Structural stability and electronic properties of JTMDs/WS2 vdW heterostructures with AC and AD stacking were investigated which are the most stable configuration compared with other configurations based on the binding energy and the interlayer distance. Results show that the Janus MoSTe/WS2, MoSSe/WS2, and AD-configuration of WSSe/WS2 vdW heterostructures are indirect bandgap semiconductor, but WSSe/WS2 with ACconfiguration is a direct bandgap. The JTMDs/WS2 vdW heterostructures exhibited a bandgap in the range of 1.54 to 0.54eV. In addition, MoSSe/WS2 and MoSTe/WS2 heterostructures displayed a type-II band alignment which is important to improve the photoelectric conversion efficiency. However, the band alignment of WSSe/WS2 heterostructure is difficult to identify and need additional calculations. First principles study shows that the investigated 2D heterostructures have a suitable bandgap for photovoltaic applications. Among the JTMDs/WS2 vdW heterostructures, MoSSe/WS2 and MoSTe/WS2 manifest type-II band alignment, making them promising candidates for photovoltaic (PV) applications. | en_US |
| dc.identifier.uri | http://etd.aau.edu.et/handle/12345678/22354 | |
| dc.language.iso | en_US | en_US |
| dc.publisher | Addis Ababa University | en_US |
| dc.subject | JTMDs/WS2 heterostructures | en_US |
| dc.subject | Type-II band alignment | en_US |
| dc.subject | bandgap | en_US |
| dc.subject | photovoltaic | en_US |
| dc.title | Electronic Properties of 2D Vander Waals Heterostructures of Janus Transition Metal Dichalcogenides with WS2 Monolayer for Photovoltaic Devices: A First Principle Study | en_US |
| dc.type | Thesis | en_US |