Abstract
Monolayer molybdenum disulfide (MoS2), as a two-dimensional material, is an n-type semiconductor with direct band gap suitable for optoelectronic applications. Moreover, the surface of monolayer MoS2 contains no nonbonding dangling bonds; therefore, it can form van der Waals heterojunctions with other semiconductor materials. Integration of monolayer MoS2 and bulk semiconductor materials can enhance the total absorption in photovoltaic devices. In this work, monolayer MoS2 fabricated by CVD method were transferred on either p-type Si(100) substrates or p-type epitaxial GaAs films to form heterojunction p-n solar cells. In p-Si/MoS2 solar cells, we first investigated the most appropriate doping concentrations of Si substrates to yield heterojunction solar cells with the best power conversion efficiency. Then, different top electrode materials were studied in order to decrease the series resistance of the cells. The best power conversion efficiency obtained in p-Si/MoS2 solar cells was 3.362 %. In p-GaAs/MoS2 solar cells, a variety of GaAs thin films with different doping concentrations were grown on highly p-doped GaAs(100) substrates by MBE. The thickness of the film was optimized, and multilayer structures were attempted to find out the highest efficiency. The best power conversion efficiency in p-GaAs/MoS2 solar cells was 0.406 %.