Dependence of spectroscopic and electrical properties on the size of cadmium sulfide nanoparticles

Cadmium sulfide (CdS) nanoparticles with different sizes were synthesized using chemical precipitation method. The change of particle size, morphologies and crystal structures with the molar ratio of cadmium to sulfide salt was obtained from transmission electron microscopy (TEM) and X-ray diffraction pattern results. It should be noted that, the CdS nanoparticles were formed with different size, normal distribution and cubic phase. The effect of particle sizes on the optical properties was confirmed from UV–visible and fluorescence spectroscopic data. The optical band gap decreases from 2.9 to 2.51 eV with increasing the particle size from 5 to 9.25 nm due to the change of the molar ratio of CdCl2 to Na2S from (16:1) to (1:16). The electrical results obtained show that, DC conductivity increase with decreasing the particle sizes. The conduction mechanisms were discussed at low and high applied voltage. All samples have semiconducting behavior and can be used in the field of light emitting diodes.

We used different molar ratios of CdCl2 and Na2S to prepare CdS nanoparticles by chemical precipitation method and to control the particle sizes. The effects of the particle size on the optical and electrical properties were confirmed.Figure optionsDownload as PowerPoint slideHighlights
► In this study cubic phase of cadmium sulfide nanoparticle with different sizes was prepared by chemical precipitation method.
► Effects of cadmium to sulfur molar ratio on the particle sizes was clarified.
► Energy gap and optical properties were affected by the particle sizes.
► Electrical conductivity was improved with decreasing the particle sizes.