Preparation and Study of the Optical Properties of Zns Zinc Oxide Films Used in the Manufacture of Solar Cells Prepared by the Chemical Spray Pyrolysis Method

Abstract

In this research, copper oxide (ZnS) films used in solar cells were prepared by thermal chemical spraying method using aqueous copper chloride (CuCl2 .2H2O) as a starting material at a concentration of (0.1M), and the films were prepared on glass substrates heated to a temperature of (350˚C).

The optical properties of the (ZnS) thin film were studied (transmittance, absorbance, absorption coefficient, energy gap, reflectivity, refractive index, extinction coefficient and finally optical conductivity) and for the wavelength range (190-1100) nm, the transmittance recorded high values in the visible spectrum region, while the absorbance spectrum, which is high at short wavelengths, decreases at long wavelengths. In addition, the optical energy gap (Eg) of the thin film for direct transition of both allowed and forbidden types was calculated and found to be equal to 2.113 eV and 2.095 eV respectively.

The results of optical tests showed that the absorption coefficient values of the films are greater than (104 cm-1), which indicates the occurrence of direct electronic transitions.

As for the reflectivity and refractive index, it was found that they increase significantly at photon energies corresponding to the energy gap of all films. It was also found that the extinction coefficient increases at photon values less than the absorption edge and is followed by a clear increase. The optical conductivity was also studied and found to increase rapidly at photon energies close to the absorption edge until it reaches its maximum value.