Studies on optical absorption and photoluminescence of thioglycerol-stabilized CdS quantum dots.
Nanoparticles of CdS were prepared at 303 K by aqueous precipitation method using CdSO4 and (NH4)2S in presence of the stabilizing agent thioglycerol. Adjustment of the thioglycerol (T) to ammonium sulphide (A) ratio (T:A) from 1:25 to 1:3.3 was done during synthesis and nanoparticles of different size were obtained. The prepared colloids were characterized by UV-vis and photoluminescence (PL) spectroscopic studies. Prominent first and second excitonic transitions are observed in the UV-vis spectrum of the colloid prepared with a T:A ratio of 1:3.3. Particle size analysis was done using XRD, high resolution TEM and dynamic light scattering and found to be approximately 3 nm. UV-vis and PL spectral features also agree with this particle size in colloid with T:A of 1:3.3. The band gap of CdS quantum dots has increased from the bulk value 2.4-2.9 eV. PL spectra show quantum size effect and the peak is shifted from 628 to 556 nm when the ratio of T:A was changed from 1:25 to 1:3.3. Doping of CdS with Zn2+ and Cu2+ is found to enhance the PL intensity. PL band shows blue-shift and red-shift on doping with Zn2+ and Cu2+, respectively. UV and PL spectral features of the CdS/Au hybrid nanoparticles obtained by a physical mixing of CdS and Au nanoclusters in various volume ratios is also discussed. Au red-shifts and rapidly quenches the PL of CdS. An additional low energy band approximately 650 nm is observed in the UV visible spectrum of the hybrid nanoparticles.
Unni
C
C
Department of Electronics and Communication Engineering, TKM College of Engineering, Kollam 691005, India.
Philip
Daizy
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Gopchandran
K G
KG
D019187:Cadmium Compounds / Q000737:chemistry; D002384:Catalysis; D003300:Copper / Q000737:chemistry; D005990:Glycerol / Q000031:analogs & derivatives / Q000737:chemistry; D053758:Nanoparticles / Q000737:chemistry; D036103:Nanotechnology / Q000379:methods; D010316:Particle Size; D045663:Quantum Dots; D011789:Quantum Theory; D013053:Spectrophotometry / Q000379:methods*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013440:Sulfides / Q000737:chemistry; D013696:Temperature; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction; D015032:Zinc / Q000737:chemistry
D019187:Cadmium Compounds; D013440:Sulfides; C034939:cadmium sulfide; D014867:Water; D003300:Copper; C009465:thioglycerol; D015032:Zinc; D005990:Glycerol