Hydrothermal processed heterogeneous MoS₂ assisted charge transport in dye sensitized solar cells

Photovoltaic performance in dye sensitized solar cells (DSSCs) was improved by incorporating hydrothermal processed molybdenum disulfide (MoS₂) into the bulk of titanium dioxide (TiO₂) nanoparticle film. MoS₂ exhibits a heterogeneous morphology comprising randomly distributed clustered nanoparticles and one dimensional nano-needles. The heterogeneous MoS₂ was examined by X-ray photoelectron spectroscopy to study Mo 3d and S 2p peaks. Transmission electron microscopic studies on the heterogeneous MoS₂ assert the presence of multilayers which further confirmed by UV–visible optical absorption spectroscopy showed absence of band-edge excitonic peaks at 612 nm and 674 nm. DSSCs show 17% enhancement in performance for 0.09 wt% of heterogeneous MoS₂ incorporated TiO₂ nanoparticle film compared to reference DSSC fabricated using only TiO₂. Further changes in performance was examined by varying the concentration of MoS₂ in TiO₂ and observed that there is an optimum value to facilitate photo-generated charge transport kinetics in TiO₂. The heterogeneous nature of MoS₂ effectively acquired photo-electrons from TiO₂ due to the presence of conduction band edge few meV below than that of in TiO₂ and helps improving the performance.