Abstract:
Cadmium telluride (CdTe) is a vital semiconductor material which can absorb most of the
electromagnetic radiation of solar energy spectrum to yield more efficient solar cells. Among
the thin film fabrication methods, electrodeposition is an emerging technique to produce good
quality CdTe materials using either two or three electrode system. This study was performed
using the two electrode electrolytic system to investigate the effect of Cd2+ concentration on the
material properties of CdTe thin films to enhance its photovoltaic activities.
Electrodepositions of CdTe were carried out in an aqueous electrolyte which was prepared
utilizing analytical grade CdSO4 as the cadmium and TeO2 as the tellurium precursors. Fluorine
doped tin oxide coated conducting glass (1×3 cm2) and high purity carbon electrode were used
as the working (cathode) and counter electrodes (anode) respectively in the electrolytic cell used
for the depositions. The concentration of TeO2 was maintained around 1 mmol/L throughout
while varying the CdSO4 concentration from 1.00 mol/L to 1.50 mol/L. pH of the electrolyte
was initially adjusted to 2.2 and depositions were carried out in the cathodic potential range of
(1.33 - 1.37) V at 65 °C while stirring at continuous stirring rate of 60 rpm. The resulting
electrodeposited CdTe layers were heat treated for 10 minutes at 400 °C in air and subsequently,
their optical, electrical morphological and structural properties were studied using UV-visible
spectrophotometry, photo-electrochemical cell, scanning electron microscopy and X-ray
diffraction spectroscopy. As elucidated by the results, at the deposition potentials of 1.34 V and
1.35 V, the short circuit current and open circuit voltage values were increased with the
increasing of concentration of Cd2+ from 1.00 mol/L to 1.25 mol/L while the band gap energy
reached to its theoretical value of 1.50 eV.
