Determination of the energy band gap of thin films of cadmium sulphide, copper phthalocyanine and hybrid cadmium sulphide/copper phthalocyanine from its optical studies

Abstract

Cadmium sulphide (CdS) thin films are prepared onto glass substrates by chemical bath deposition technique (CBD). Thin films of copper phthalocyanine (CuPc) are also sublimed onto glass substrates in high vacuum at room temperature. Hybrid CdS/CuPc (organic–inorganic) thin films are obtained from CdS films grown on glass substrates by CBD technique and subsequently vacuum subliming CuPc onto them. These films are annealed in air at different temperatures. Optical studies are separately done on CdS, CuPc and hybrid CdS/CuPc thin films. Optical properties are studied (between 300 and 900 nm) in a UV–VIS Spectrophotometer and the absorbance recorded as a function of photon energy. The optical band gap and maximum absorption coefficient of the as-deposited and annealed samples are determined.