Effect Of Capping Agents And Annealing On The Optical Properties Of (Cd0.8-Zn0.2)S And (Cd0.8-Zn0.2)S:Eu Films Prepared By CBD Technique

Abstract

Thin films of (Cd0.8-Zn0.2)S and (Cd0.8-Zn0.2)S:Eu are prepared by Chemical Bath Deposition (CBD) technique on glass substrates at 60ºC temperature by adding Mercaptoethanol and Methanol as capping agents(CA). The films were annealed at 400°C for two minutes and their optical properties were studied. The effect of the presence of capping agents and annealing was investigated. The optical constants such as refractive index, extinction coefficient, optical and electrical conductivity, real and imaginary dielectric constants were determined and their nature discussed. The Optical Absorption spectra shows a blue shift in the absorption edge in the presence of capping agents indicating quantum confinement effects on reduction in particle size. The values of optical band gap were obtained from Tauc’s plots and were found to increase in the presence of capping agents but decrease on annealing. Higher transmittance and correspondingly lower absorbance in the Visible and NIR region was observed in both unannealed and annealed films deposited in the presence of capping agents. These nanocrystalline (Cd0.8-Zn0.2)S films exhibiting high transmittance and low absorbance are thus good candidates for application as antireflection coatings in solar cells.