Photoelectrochemical (PEC) Investigation of Ga‐Doped MoBi₂Se₅ Thin Films Deposited by Arrested Precipitation Technique

Abstract

Nanocrystalline Ga‐doped molybdenum bismuth selenide thin films have been deposited onto amorphous and fluorine‐doped tin oxide (FTO) coated glass substrate using arrested precipitation technique (APT), which is based on self‐organized growth process. Deposited thin films of MoBi(2‐x)GaxSe5 are characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), and X‐ray photoelectron spectroscopy (XPS). XRD analysis shows mixed phase type crystal structure of MoBi(2‐x)GaxSe5 thin films. SEM analysis shows that closely packed grains provide a pinhole‐free morphology. The average surface roughness of as deposited MoBi(2‐x)GaxSe5 (x = 0.0, 0.04, and 0.10) thin films obtained from AFM images is 5.04 nm μm‐2. In TEM analysis, lattice plane (015), (103), and (103) are observed in SAED pattern, which confirms mixed phase type crystal structure of MoBi(2‐x)GaxSe5 thin films. The binding energy, elemental composition, and surface nature of MoBi(2‐x)GaxSe5 thin film is confirmed by using XPS. The photoelectrochemical (PEC) investigations are carried out using cell configuration p‐MoBi(2‐x)GaxSe5(FTO)/0.5M (Na2Sx‐ NaOH‐S)/counter electrode. After Ga doping, MoBi2Se5 thin film electrodes exhibit photoactivity in sulphide/polysulphide electrolyte toward positive polarity (p‐type behavior). On the addition of gallium, power conversion efficiency of MoxBi(2‐x)GaxSe5 thin films decreases from 0.456 to 0.171%.