Nanofilms of Zinc Oxide (ZnO) were fabricated from solutions of zinc tetraoxosulphate heptahydrate, citric acid, and sodium hydroxide onto a Fluorine Tin Oxide (FTO) conductive glass by elecrodeposition process. Time as bath parameter was varied. Three samples with time interval of 30 seconds, 60 seconds and 90 seconds were fabricated. Absorbance of the films was determined with the help of spectrophotometer. Other optical properties of the nanofilms were calculated using the appropriate equations from the literature. The deposited nanofilms have high absorbance in UV region and low absorbance in VIS -NIR region. Transmittance of the nanofilms is low in UV region and high in VIS -NIR region. Reflectance of the films is low throughout the UV -VIS -NIR regions. The optimal optical thickness of 270 nm was obtained at 90 seconds. The bandgap of the nanofilms obtained is between 3.30 to 3.60 eV. Average crystallite size of 43.04 nm was obtained for the deposited ZnO thin film.

Semiconductor thin films of CuMnS have been deposited onto conductive fluorine-doped tin oxide (FTO) glass substrate using an electrodeposition method to investigate their properties for possible applications. Copper sulfate, manganese sulfate and Thiourea were precursors used for sources of copper, manganese and sulphur ions respectively. The concentration of manganese ions was varied while keeping deposition voltage and time constant at 0.6 and 100 s, respectively. The films were characterized for optical, structural and morphological properties. The results obtained showed that the absorbance of the films is high in the visible (VIS) and near-infrared (NIR) regions but decreases towards NIR. The films transmittance is low in the VIS but increased in the NIR regions. The extinction coefficient is low in the VIS and NIR regions and decreases as concentration of manganese ion increased. The refractive index is high and initially increased slightly from 4.49 to 4.68 in the mid-VIS region while manganese concentration increased from 0.05 to 0.15 M and then decreased to the value of 2.73 as concentration of manganese ion increased further. The optical conductivity is high throughout the VIS and NIR regions while the optical bandgap energy is in the range of 1.5 to 2.05 eV and increases as manganese ion concentration increased. The XRD analysis showed that the deposited thin films of CuMnS are crystalline with average crystallite size and micro-strain in the range of 15.86 - 24. 45 nm and 3.97×10–3 - 6.13×10–3, respectively. The SEM results showed that the films are composed of particle sizes that are spherical in shape, uniform in sizes and densely packed together and consequently make the film surface rough. These properties exhibited by the films make them good materials for applications in photovoltaic calls, solar control coatings, photothermal applications and many other electronic devices that require high temperatures. HIGHLIGHTS This paper focused on the study of the effect of manganese ion concentration on the chalcogenide semiconductor thin films of CuMnS for possible device applications Electrodeposition method was used to fabricate the semiconductor thin films of CuMnS Optical, Structural and morphological properties of the thin films were characterized The deposited thin films of CuMnS were found to have good applications for photovoltaic cells and other optoelectronic device fabrications GRAPHICAL ABSTRACT

Undoped and cobalt doped copper selenide thin films have been successfully prepared unto fluorine tin oxide (FTO) substrates by electrodeposition method using copper acetate, cobalt nitrate and selenium (IV) oxide as precursors for copper, cobalt and selenium ions respectively. Deposited thin films were subjected to optical, structural, morphological, compositional and electrical analysis using spectrophotometer, x-ray diffractometer, scanning electron microscope (SEM), energy dispersive x-ray spectroscopy (EDS) and 4-point probe. Optical results observed between the wavelength range of 300 nm and 1,000 nm showed that the films have good optical responses. Absorbance values ranged between 0.1 and 0.81 while transmittance lies between 15.59 and 78.68 %. Energy band gap of the films was found to vary from 2.10 to 2.28 eV. These results showed that cobalt as a dopant could be used to modify properties of copper selenide thin films. Structural analysis showed that the deposited films are polycrystalline in nature with hexagonal structural phase. Crystallite sizes of range 27.56 to 34.27 nm were obtained while dislocation density lied between  and . Microstrain ranged between and . Micrograph images showed flake-like particles that increased in size as percentage of cobalt increased. Energy dispersive spectroscope (EDS) results confirmed the incorporation of cobalt on the deposited copper selenide films. Electrical resistivity of the films increased from  to  while conductivity decreased from  to  as a result of variation in cobalt ion concentration. These properties of the deposited thin films positioned them for solar cell and optoelectronics device applications. HIGHLIGHTS Energy band gap of electrosynthesized cobalt doped copper selenide ranged from 2.10 to 2.28 eV Film thickness values ranged from 48.41 and 176.79 nm. Thickness values of the films were found to increase as concentration of cobalt increase Increase in dopant concentration resulted to shift in diffraction peaks towards larger angles Increase in crystallite size from 27.56 - 34.27 nm was observed as dopant concentration increases SEM images of the films revealed flake - like particles of different sizes GRAPHICAL ABSTRACT

The properties of PbMnS semiconductor thin films deposited on fluorine-doped tin oxide (FTO) substrate using an electrodeposition method are investigated to determine their possible device applications. Lead acetate, manganese sulfate, and thiourea were used as precursors for sources of lead, manganese, and sulfur ions respectively. The concentration of lead, manganese, and sulfur ions sources with deposition voltage of 1.8 V was kept constant. The films were deposited using three electrodes system of electrodeposition method by varying deposition time. The films were characterized for optical, structural, morphological, and compositional properties and results showed that the absorbance, refractive index, and optical conductivity of the films are high in the visible (VIS) and near-infrared (NIR) regions but decreases in the NIR. These three properties initially increased with an increase in deposition time up to a time of 70 s which has the highest values of these properties before decreasing to lower values. The transmittance and extinction coefficient of the films are low in both VIS and NIR regions. The bandgap energy of PbS was found to be blue shifted with values of 1.51 eV, 1.54 eV, 1.60 eV, 1.45 eV, and 1.35 eV for the films deposited at 30 s, 50 s, 70 s, 90 s, and 110 s respectively. XRD analysis showed that the films are crystalline with sharp peaks positions indexable to crystalline planes of (111), (200), (211), (220), (311) and (400) with average crystallite size in the range of 16.110 nm to 17.218 nm. Energy-dispersive X-ray spectroscopy (EDX) results showed that the films are composed of lead, manganese, and sulfur but there are some impurity elements present mostly as a result of the substrate used. These properties exhibited by the deposited thin films of PbMnS showed that they can be used for many optoelectronic applications such as photovoltaic cells, sensors, photoconductors, etc.

Semiconductor thin films of lead manganese sulphide (PbMnS) have been successfully deposited on florinated tin oxide (FTO) conductive glass substrate using an electrodeposition method. Lead acetate (Pb(CH3COO)2), manganese sulphate (MnSO4.H2O) and thiourea (CH4N2S) were the precursor used for cadmium (Cd2+), manganese (Mn2+) and sulphur (S2-) sources respectively. The concentration of manganese (Mn2+) was varied while keeping the concentrations of Pb2+ and S2- constant at 0.2 M and 0.1 M respectively. The deposited films were annealed at temperature of 250 oC and subjected for optical, electrical, structural and morphological characterizations. The results of the characterizations showed that the deposited thin films of PbMnS have high absorbance, high absorption coefficient throughout VIS and NIR regions. The band gap energy of the films is tuned to the order of 1.9 eV to 2.0 eV and tends to constant as concentration of Mn2+ increased. The electrical properties (electrical resistivity and conductivity) of the films are dependent on the concentration of Mn2+ and film thickness. The range of values of the electrical properties is found to be within the range of values for semiconductor materials. The XRD analysis revealed that the deposited thin films of PbMnS is crystalline but the crystallinity declined with increase in concentration of Mn2+. The SEM morphology showed that the surfaces of the films are highly homogeneous in nature and particle sizes are uniform on the substrate with the majority of the particles been spherical in shape. These observed properties exhibited by the deposited thin films of PbMnS make the films good materials for many optoelectronic and electronic applications such as solar cell, light emitting diode (LED), photodetector etc.