Tuning Photovoltaic Properties of Two-dimensional Molybdenum Disulfide by Alloying: An ab initio study

Abstract: Addressing the urgent need for innovative energy solutions amidst increasing environmental concerns, the focus on photovoltaic solar cells is intensifying. Currently limited by the Shockley-Queisser limit, conventional silicon-based solar cells offer a maximum power conversion efficiency of 32%. This limitation has inspired exploration into alternative materials such as two-dimensional multi-junction heterogeneous structures, notably two-dimensional molybdenum disulfide (2D-MoS2). With a 1.86 eV bandgap and remarkable mechanical strength, 2D-MoS2 presents a potential for higher power conversion efficiency and flexibility, with an exceptional ability to accept doping atoms. This study uses the Vienna ab initio Simulation Package to predict the performance of alloyed 2D-MoS2. Transition metals are added into the structure, with specific pairs showing a promising ability to optimize the bandgap. Hybrid density functional theory methods are used to investigate the effects of alloying on the electronic structure and optical absorption. Niobium-technetium, zirconium-ruthenium, and yttrium-rhodium alloyed 2D-MoS2 show potential for greater light absorption under natural light. The bandgap is tunable between 0.51 eV and 2.13 eV through varying alloying elements and concentrations. All structures demonstrate satisfactory thermal stability. Consequently, this alloying strategy holds potential for next-generation solar cells, though experimental testing is needed.