Abstract

Solar energy is a renewable and abundant source to reduce the dependence on traditional energy sources. Current research efforts aim to improve the efficiency of solar cells and reduce manufacturing costs. This dissertation investigates Janus transition metal dichalcogenides MoXY and WXY (X, Y = S, Se, Te; X ̸= Y) as potential absorber materials for solar cells. A systematic analysis of the inter- face stacking and composition of bilayers is presented to provide comprehensive understanding of their potential in photovoltaics. Using first-principles calcula- tions, candidates are identified that possess a direct band gap with type-II band alignment, which is desirable for achieving high-efficiency solar cells. Out of the 60 bilayers studied, 23 exhibit a direct band gap with type-II band alignment: 2 MoSSe-WSSe bilayers, 10 MoSeTe-WSSe bilayers, and 11 MoSSe-MoSeTe bilay- ers. The charge transfer properties, absorption coefficients, and power conversion efficiencies are determined. The results demonstrate that the interface compo- sition can strongly enhance the power conversion efficiency, while the interface stacking plays a less significant role. They aid the design of advanced photovoltaic materials that can facilitate future advancements in solar cell technology.