One-step hydrothermal synthesis of marigold flower-like nanostructured MoS2 as a counter electrode for dye-sensitized solar cells

• Published in: Journal of solid state electrochemistry 2018-11, Vol.22 (11), p.3331-3341
• Main Authors: Senthilkumar, R., Ramakrishnan, S., Balu, Murali, Ramamurthy, Praveen C., Kumaresan, Duraisamy, Kothurkar, Nikhil K.
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Carrier mobility; Characterization and Evaluation of Materials; Charge efficiency; Charge transfer; Chemistry; Chemistry and Materials Science; Condensed Matter Physics; Current carriers; Dye-sensitized solar cells; Dyes; Electrochemical analysis; Electrochemical impedance spectroscopy; Electrochemistry; Electrodes; Energy conversion efficiency; Energy Storage; Flowers; Fluorine; Hall effect; Maximum power; Molybdenum disulfide; Morphology; Nanostructure; Original Article; P-type semiconductors; Photovoltaic cells; Physical Chemistry; Raman spectroscopy; Scanning electron microscopy; Spectrum analysis; Substrates; Synthesis; Thin films; X-ray diffraction
• ISSN: 1432-8488; 1433-0768
• DOI: 10.1007/s10008-018-4043-7

MoS 2 thin films with marigold flower-like nanostructures were grown on conductive fluorine-doped tin oxide (FTO) substrates through a one-step hydrothermal synthesis for their application as counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). Different MoS 2 thin film samples (A–D) were grown on FTO slides using different concentrations of precursors (sodium molybdate and thioacetamide), while keeping the Mo/S molar ratio constant (1:4.6), in all samples. The effect of varying precursor concentrations (3.2–12.6 mM on MoS 2 basis) on the structure of the nanostructured thin films and their performance as DSSC-CEs was investigated. Scanning electron microscopy revealed a material with an infolded petal-like morphology. With increasing precursor concentration, the petal-like structures tended to form bunched nanostructures (100–300 nm) resembling marigold flowers. X-ray diffraction analysis, X-ray photoelectron, and Raman spectroscopy studies showed that the thin films were composed of hexagonal MoS 2 with good crystallinity. Hall effect measurements revealed MoS 2 to be a p-type semiconductor with a carrier mobility of 219.80 cm 2  V −1  s −1 at room temperature. The electrochemical properties of the thin films were examined using cyclic voltammetry and electrochemical impedance spectroscopy. The marigold flower-like MoS 2 thin films showed excellent electrocatalytic activity towards the I¯/I 3 ¯ reaction and low charge transfer resistance ( R ct ) values of 14.77 Ω cm −1 , which was close to that of Pt electrode (12.30 Ω cm −1 ). The maximum power conversion efficiency obtained with MoS 2 CE-based DSSCs was 6.32%, which was comparable to a Pt CE-based DSSC (6.38%) under one sun illumination. Similarly, the maximum incident photon-to-charge carrier efficiency exhibited by MoS 2 CE-based DSSCs was 65.84%, which was also comparable to a Pt CE-based DSSC (68.38%). The study demonstrated that the marigold flower-like nanostructured MoS 2 films are a promising alternative to the conventional Pt-based CEs in DSSCs. Graphical abstract ᅟ