Performance evaluation of 2D MoS₂-based solar cells and realization of transparent ultra-thin devices

Abstract

Molybdenum disulfide (MoS2) is an alternate absorber layer in 2D solar cells owing to its potential of proficient sunlight harvesting. The optimum electrical and optical properties of MoS2 validate it as a suitable photovoltaic absorber material. This work investigates the performance of 2D (and multi-layer) MoS2-based vertically stacked solar cell by numerical simulation process using one dimensional Solar Cell Capacitance Simulator (SCAPS). Two device configurations based on Schottky junction (ITO/n-MoS2/Au) and pn junction (ITO/n-MoS2/p-MoS2/Au) have been theoretically analyzed. The feasibility of ultra-thin transparent solar cells is also demonstrated, which is motivating from a technological outlook. Initially, the properties of the active layers are optimized to give the highest performance. The findings are explained on the basis of band alignment between the electrodes and the different layers. The potential barrier developed at the interface of different materials governs the output of the cells. The calculations forecast the material properties, which need to be tuned to fabricate solar cells with enhanced efficiency. After optimization, the highest efficiency obtained for single n-MoS2-based solar cell is 10.22%, while for the pn junction solar cell it is 16.86%. The optimized cells exhibit high open circuit voltages of ~ 1.2 V, which is an essential factor for commercial realization of solar cells. Lastly, the performance of transparent solar cells based on thin 2D MoS2 films has been predicted which showcases the efficiency in the range of 0.78-4.36%. These homo-junction device investigations of solely MoS2 layer along with employment of a strict control on the defects during deposition and fabrication of MoS2-based solar cells can ensure better performance of the device. Thus, it can open ways to develop next generation feasible solar cells with higher power density as compared to existing technology.