Abstract:
Mn doped CdS thin films were fabricated over fluorine doped tin oxide (FTO) glass by the
chemical bath deposition (CBD) method. In this work, effect of deposition temperatures
(60 °C, 70 °C, 80 °C), different pHs (8, 10, 12), different surfactant amounts (20 mg, 40
mg, 60 mg) and different precursor concentrations (100% Cd, 98% Cd and 90 % Cd) on
the structural, morphological, optical and optoelectrical properties of Mn doped CdS thin
films was studied. Different morphologies like nano balls, nano cubes, nano petals, nano
flakes, nano worms, nano sheets were obtained by CBD method with different deposition
conditions. A maximum of 2% successful Mn doping was achieved. Structural and
morphological analysis were done by powder X-ray diffraction (XRD), Raman
spectroscopy, scanning electron microscopy-energy dispersive X-rays (SEM-EDX),
elemental mapping, and UV-Visible spectroscopy. Optical profilometry was done for
thickness and roughness of thin films. XRD showed the hexagonal wurtzite phase of CdS
thin films grown over FTO glass. Red shift in band gaps were observed by the successful
Mn doping in CdS. The Photoelectrochemical (PEC) applications were studied by
conventional three electrode system with Mn-doped CDS FTO as working electrode,
platinum wire as auxiliary electrode and Ag/AgCl/ 3M KCl as reference electrode in 0.1
M KCl (neutral pH) electrolyte solution. All morphologies gave better PEC response for
oxygen evolution reaction than pure CdS films, however, the electrodes prepared at 80°C,
pH 8, 20 mg SDS surfactant amount and with 2% successful Mn doping gave the porous,
high surface area nano-beads morphology which showed the maximum current density of
~ 50 μA/ cm2 at 0.5 V external potential under sunlight illumination. Preliminary study on
IR sensing was also performed in solid-state.
