Effect of molarities on structural and optical properties of type-II heterostructure CdS/PbS core/shell quantum dot
- 23 Downloads
The interrelation between particle sizes and crystal structure in core/shell (CS) semiconductor quantum dots has elicited widespread interest. The effects of precursor concentration of chemically synthesized CdS/PbS CS nanoparticles on structural and optical properties have been reported. CdS/PbS CS QDs shows polycrystalline nature with hexagonal phase in X-ray Diffraction (XRD) pattern, which was also confirmed from SEAD pattern. The particle size was found about 15 nm from the HRTEM images, which was also exhibited CS structure of the NPs. EDX and XRD pattern exhibited the formation of pure CdS/PbS CS structure NPs. The strain in the small spherical NPs is dominant; resulting is shifting of XRD peaks towards higher 2θ values and is found to decrease with an increased crystal size of the core. The effect of molarities on the size of the NPs has seen in the absorption spectra and emission spectra with red shifted. The bandgap of the CS NPs varies inversely with the molar concentration of the nanocrystals. The luminescence intensity exhibited increasing trend with the molar concentration of the nanocrystals. The optical properties were found to be in agreement with the structural properties of the CS NPs.
We acknowledge Dept of Physics, IIT Guwahati for providing us with XRD measurements and SAIF, NEHU, Shillong for providing facilities for HRTEM. Also, I would like to thanks CSIR-HRDG, Delhi for JRF grand [08/446(0001)2014-EMR-1].