Background: Cadmium sulfide (CdS) based semiconductors are of great interest for different
high-end applications because they pose a direct bandgap (2.42 eV). CdS are used as the main
constituent material in many applications, namely solar cells, electroluminescent, and quantum dot
light-emitting diodes. Transition metal-doped CdS revealed considerable influence in the bandgap,
photoluminescence properties and peak energy upon increasing the metal content.
Objective: In this work, we study the single-phase cubic structure of CdS. Photoluminescence spectra
revealed a strong blue emission peak located at about 445 nm.
Methods: We investigate the Co-doping CdS semiconductor nanoparticles prepared via the chemical
co-precipitation method using thiophenol as template, 300 °C/2h in vacuum optimum temperature and
period of annealing to yield nanosized particles. Morphology and structural studies of the particles
were using XRD, and TEM, respectively.
Results: XRD and TEM studies for the calcined samples revealed a cubic structure. The crystalline
size was in the range of 10-17 nm. Thermogravimetric analysis (TGA) was employed to stabilize the
temperature of annealing for the samples. The blue shift in the spectra and the band gap value of Codoped
CdS nanoparticles were estimated using UV-vis absorption spectra. Photoluminescence spectra
revealed a strong blue emission peak around 445 nm indicating the presence of surface states within
the bandgap region, which is a characteristic feature of nanoparticles.
Conclusion: XRD analysis indicated zinc blend structure and the intensity decreased with increasing
Co content. TEM images show that the particles are spherical in shape with average sizes around 13
nm. Luminescence of the synthesized nanoparticles exhibited blue emission between 400 – 500 nm
with the peak located at about 445 nm. The emission intensity increased with the increase in Co concentration.