Analysis of the generation mechanism of the S-shaped J—V curves of MoS₂/Si-based solar cells

Amorphous-microcrystalline MoS_2 thin films are fabricated using the sol-gel method to produce MoS_2/Si-based solar cells. The generation mechanisms of the S-shaped current density-voltage (J-V) curves of the solar cells are analyzed. To improve the performance of the solar cells and address the problem of the S-shaped J-V curve, a MoS_2 film and a p^+ layer are introduced into the front and back interfaces of the solar cell, respectively, which leads to the formation of a p-n junction between the p-Si and the MoS_2 film as well as ohmic contacts between the MoS_2 film and the ITO, improving the S-shaped J-V curve. As a result of the high doping characteristics and the high work function of the p^+ layer, a high-low junction is formed between the p^+ and p layers along with ohmic contacts between the p^+ layer and the Ag electrode. Consequently, the S-shaped J-V curve is eliminated, and a significantly higher current density is achieved at a high voltage. The device exhibits ideal p-n junction rectification characteristics and achieves a high power-conversion efficiency (CE) of 7.55%. The findings of this study may improve the application of MoS_2 thin films in silicon-based solar cells, which are expected to be widely used in various silicon-based electronic and optical devices.