Enhanced photoelectrochemical performance of novel p-type MoBiCuSe4 thin films deposited by a simple surfactant-mediated solution route

Abstract

Low-dimensional nanostructures with reduced grain boundaries show superior charge transportation in a photoelectrochemical cell. Therefore, nanostructures of MoBiCuSe₄ thin films deposited using different surfactants are expected to be favorable for providing a direct pathway for smooth transport of photogenerated charge carriers across a reduced number of grain boundaries within the photoelectrode. In the present investigation, we have studied the effect of different surfactants, such as polyethylene glycol (PEG), sodium dodecylsulfate (SDS) and trioctylphosphine oxide (TOPO), on the opto-structural, morphological and photoelectrochemical (PEC) properties of MoBiCuSe₄ thin films. We have demonstrated a soft chemical route that facilitates the formation of a compact, homogeneous deposition with a large effective (photoactive) surface area, which could be suitable for PEC cells. The MoBiCuSe₄ thin films have been deposited using the arrested precipitation technique (APT) and their formation confirmed by energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The nanocrystalline nature of the MoBiCuSe₄ thin films and the mixed rhombohedral crystal structure with reduced number of grain boundaries were confirmed by the X-ray diffraction (XRD) pattern. The direct allowed type of transition in the material, with an average absorption coefficient above 10⁴ cm⁻¹, makes it suitable for PEC applications. The maximum light conversion efficiency achieved for MoBiCuSe₄ thin films deposited with surfactant is 0.18%. PEC analysis verifies that the synthesized nanostructures of the surfactant-assisted MoBiCuSe₄ photoelectrode material are suitable for PEC cells.