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

Abstract

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.