Georgies, Alene (PhD)Girma, Mekonnen2021-02-232023-11-282021-02-232023-11-282020-09http://etd.aau.edu.et/handle/12345678/25196Stacking of two-dimensional materials into layered Van der Waals heterostructures are recently considered as a promising candidate for applications on photovoltaic devices because they can combine advantages of individual‟s 2D materials. Janus transition metals dichalcogenides (WSSe) have emerged because of favorable electronic properties as an attractive absorbing material. We therefore systematically examine the geometric features, electronic properties, work function, and density of states, band alignment of monolayer ZnO and WSSe and their heterostructures in this work using density functional theory methods (DFT) with PBE calculations as implemented in the Quantum ESPRESSO and VASP codes. It was found that, the negative binding energies indicate all the four configurations of ZnO-WSSe heterostructures are stable and feasible. Moreover, three configurations B, C and D exhibit indirect band gaps of 1.6248 eV, 1.6319 eV and 1.3126 eV, respectively. But the other configuration A has direct band gap of 1.7106 eV. In addition, it is found that all four configurations show band alignment type-II. In type-II alignment, donor-acceptor interface band heterojunctions can easily promote electron and hole carrier transfer and separation at interface, which can significantly enhance the efficiency of photovoltaic solar cells. With direct band gap, configuration A is the preferred heterostructure for photovoltaic devices applications.en-US2D materialsJanus Transition metal dichalcogenidesZnOWSSedensity functional theoryphotovoltaicsThesis