Boosting the photovoltaic performance of MoS2/Si heterojunction solar cells with thiourea-doped MoS2 films

Two-dimensional molybdenum disulfide film has unique physical and chemical properties, which make it a prominent candidate for optoelectronic device applications. In this work, the high-quality few-layer MoS2 films were successfully deposited by spin-coating the ammonium tetrathiomolybdate aqueous solution doped with an appropriate amount of thiourea on p-Si substrates. The effects of thiourea doping ratio on the microstructural properties of the prepared MoS2 films were analyzed by Raman spectrum, X-ray diffraction, and X-ray photoelectron spectroscopy. It was found that the few-layer MoS2 films with high crystallinity and low defect density can be formed at the thiourea doping ratio of 0.5. The electrical and photovoltaic properties of the MoS2/Si heterojunction solar cells fabricated by using the MoS2 film with different thiourea doping ratios were investigated by current density-voltage, external quantum efficiency, and capacitance-voltage measurements. The MoS2/Si heterojunction solar cell based on the optimized thiourea doping ratio achieves a power conversion efficiency of 9.81%. The results display a simple and convenient method for preparing the high-quality MoS2 films and boosting the performance of MoS2/Si heterojunction solar cells, providing a possibility to realize the low-cost and large-area MoS2-based optoelectronic devices.