Atomically Thin-Layered Molybdenum Disulfide (MoS2) for Bulk-Heterojunction Solar Cells

Transition metal dichalcogenides (TMDs) are becoming significant because of their interesting semiconducting and photonic properties. In particular, TMDs such as molybdenum disulfide (MoS₂), molybdenum diselenide (MoSe₂), tungsten disulfide (WS₂), tungsten diselenide (WSe₂), titanium disulfide (TiS₂), tantalum sulfide (TaS₂), and niobium selenide (NbSe₂) are increasingly attracting attention for their applications in solar cell devices. In this review, we give a brief introduction to TMDs with a focus on MoS₂; and thereafter, emphasize the role of atomically thin MoS₂ layers in fabricating solar cell devices, including bulk-heterojunction, organic, and perovskites-based solar cells. Layered MoS₂ has been used as the hole-transport layer (HTL), electron-transport layer (ETL), interfacial layer, and protective layer in fabricating heterojunction solar cells. The trilayer graphene/MoS₂/n-Si solar cell devices exhibit a power-conversion efficiency of 11.1%. The effects of plasma and chemical doping on the photovoltaic performance of MoS₂ solar cells have been analyzed. After doping and electrical gating, a power-conversion efficiency (PCE) of 9.03% has been observed for the MoS₂/h-BN/GaAs heterostructure solar cells. The MoS₂-containing perovskites-based solar cells show a PCE as high as 13.3%. The PCE of MoS₂-based organic solar cells exceeds 8.40%. The stability of MoS₂ solar cells measured under ambient conditions and light illumination has been discussed. The MoS₂-based materials show a great potential for solar cell devices along with high PCE; however, in this connection, their long-term environmental stability is also of equal importance for commercial applications.