As-Deposited BaCuSe Thin Film - Morphology and Optical Properties

Barium Copper Selenide (BaCuSe) thin films were synthesized using a chemical bath deposition technique. The morphology and optical properties of these films were analyzed. Scanning Electron Microscopy (SEM) revealed that the BaCuSe films consist of smooth grains with varying sizes (400 μm to 1 mm), indicating an irregular growth rate. The transmittance spectra showed that the as-deposited BaCuSe films are transparent across the entire visible and near-infrared regions of the electromagnetic spectrum. Reflectance analysis indicated that the BaCuSe films have 0.0% reflectance in the ultraviolet region (around 175 nm), which gradually increases to 15% in the near-infrared region (950 nm). These films act as ultraviolet (UV) absorbers and visible to near-infrared (Vis-NIR) transmitters, making them suitable candidates for tandem photovoltaic cell configurations. The BaCuSe films exhibited direct and indirect bandgap energies of 1.65 eV and 0.72 eV, respectively. The refractive index analysis showed higher propagation velocities for incident photon energy in the visible to near-infrared regions compared to the ultraviolet region. The films also displayed a non-zero extinction coefficient, leading to exponential wave decay within the material. The complex dielectric constant analysis indicated weak absorption in the Vis-NIR spectrum, while optical conductivity revealed strong photonic effects between 3.5 eV and 4.05 eV. BaCuSe thin films have several promising practical applications, particularly in the fields of optoelectronics, photovoltaics, protective coating and transparent conductive layers.