Size-Controlled Cu₃VSe₄ Nanocrystals as Cathode Material in Platinum-Free Dye-Sensitized Solar Cells

Abstract

In this work, we report the first single-step, size-controlled synthesis of Cu 3 VSe 4 cuboidal nanocrystals, with the longest dimension ranging from 9 to 36 nm, and their use in replacing the platinum counter electrode in dye-sensitized solar cells. Cu 3 VSe 4 , a ternary semiconductor from the class of sulvanites, is theoretically predicted to have good hole mobility, making it a promising candidate for charge transport in solar photovoltaic devices. The identity and crystalline purity of the Cu 3 VSe 4 nanocrystals were validated by X-ray powder diffraction (XRD) and Raman spectroscopy. The particle size was determined from the XRD data using the Williamson−Hall equation and was found in agreement with the transmission electron microscopy imaging. Based on the electrochemical activity of the Cu 3 VSe 4 nanocrystals, studied by cyclic voltammetry, the nanomaterials were further employed for fabricating counter electrodes (CEs) in Pt-free dye-sensitized solar cells. The counter electrodes were prepared from Cu 3 VSe 4 nanocrystals as thin films, and the charge transfer kinetics were studied by electrochemical impedance spectroscopy. The work demonstrates that Cu 3 VSe 4 counter electrodes successfully replace platinum in DSSCs. CEs fabricated with the Cu 3 VSe 4 nanocrystals having an average particle size of 31.6 nm outperformed Pt, leading to DSSCs with the highest power conversion efficiency (5.93%) when compared with those fabricated with the Pt CE (5.85%).

Enhancing Efficiency in Dye-Sensitized Solar Cells: Incorporation of Cu3VSe4 Nanocrystals into TiO2 Photoanodes

“…The XRD pattern of Cu 3 VSe 4 nanocrystals depicted in Figure a exhibits diffraction peaks at 16.05, 27.88, 32.32, 36.21, 46.38, 49.29, 54.92, 60.17, and 67.38° Bragg’s angles relating to the (100), (111), (200), (210), (220), (300), (311), (320), and (400) crystal planes of cubical structure, with the P 4̅3 m space group matching the reference (database PDF No. #04-010-2404) . The sharp peaks in the diffraction pattern indicate the good crystallinity of Cu 3 VSe 4 nanocrystals.…”

“…The synthesis procedure follows our reported methodology . In a typical experiment, CuCl (220 mg, 2.2 mmol), VO­(acac) 2 (265 mg, 1 mmol), Se (240 mg, 3 mmol), OLA (20 mL), and 1-DDT (0.25 mL) were added to a 250 mL round-bottom flask.…”

“…We successfully demonstrated the ability to fine-tune the Cu 3 VSe 4 nanocrystal particle size in the range of ∼25 to 30 nm by tailoring the amount of surfactant utilized in the synthesis. While absorbance is in the UV–visible region of the solar spectrum, the particle size impacts the Cu 3 VSe 4 -specific absorbance wavelength, enabling the rational design of particles with desired optical properties …”