Nanoposter -2018
SAVE GIRL CHILD
“Photoluminescence of uniformly distributed ZnSe nanoparticles in PVA polymer matrix� Kamal K. Kushwaha
*
Department of Applied Physics, Jabalpur Engineering College, Jabalpur, M. P., 482001, India.
*presenting author email:- kamal_kushwah2005@yahoo.com
ABSTRACT The Luminescence properties of ZnSe/PVA were investigated with different Zn 2+ and with different PVA concentrations. These nanocomposite samples were prepared by environmental friendly chemical method. The prepared samples were characterized by using X-Ray Diffraction (XRD), Atomic force microscope (AFM) and photoluminescence (PL). The X ray diffraction revealed cubic structure of ZnSe/PVA with particle size less than 20 nm. ZnSe/PVA samples with varying Zn2+ content were excited by UV light of 230 nm and shown in figure. This PL spectrum of MSe/PVA revealed that, PL peak is found to shift towards shorter wavelength by increasing metal ion M2+ content i.e. Zn2+. The emission may be attributed to transition from various surface states of ZnSe nano. The oscillator strength is increased by reducing the size which enhances the PL intensity. The blue shift could be attributed to size reduction of ZnSe nanoparticles in PVA matrix. Due to proper passivation of surface states non-radiative transition are reduced which enhances the PL intensity. The polymer matrix acts to stabilize the nano particle. Due to the PL peak in blue region these composite films are promising materials for optical display devices.AFM observations revealed uniform distribution of MSe nanoparticles particle in PVA matrix with nanometer regime, showed strong agreement with those obtained from XRD.
Keywords: ZnSe/PVA Nanocomposite; XRD; AFM; Photoluminescence
1. INTRODUCTION 1. Polymer- inorganic nanocomposites have attracted much attention recently due to their unique size dependent chemical and physical properties [1]. 2. ZnSe
nanocomposites
exhibit
size
dependent
tunable
photoluminescence [2]. 3. Studies have been under taken to prepare ZnSe nanoparticles in PVA matrix and investigate their Photo luminescence.
1. 2. 3.
4.
2. EXPERIMENTAL ZnSe/PVA Nanocomposites were prepared by chemical method. First PVA solution was prepared in distilled water and then 1 ml ZnCl2 solution was added to it for ZnSe/PVA. After setting the pH by NH3 solution at 10, 1 ml of freshly prepared Na2SeSO3 solution was added and stirred for 90 minutes to obtain ZnSe/PVA and solution was spread on glass plates and on solvent evaporation nanocomposites films were obtained. A number of samples were prepared with different PVA concentration and subjected to X-ray diffraction and photoluminescence and Refractive Index investigations.
3. RESULT AND DISCUSSION 1. XRD pattern reveals cubic structure for ZnSe/PVA. 2. Three Peaks are obtained at 2θ=27.57˚, 45.59˚, 53.27˚ indicating reflection from (111), (220), (311) planes for ZnSe/PVA. 3. The peak corresponding to 2θ=20˚ represents PVA matrix. 4. The Particles size of samples computed from Debye Scherrer formula are obtained up to 20nm. 5. The Particle size is found to decrease by increasing PVA Concentration. 6. PVA is acting as capping agent and by increasing its concentration smaller ZnSe particles are formed in its matrix.
Fig.1. XRD pattern of ZnSe/PVA
7. Photoluminescence (PL) spectra of ZnSe/PVA samples excited by 230 nm UV light are shown in fig.2. 8. A single peak is obtained at 465 nm for ZnSe/PVA and the higher intensity is observed by increasing PVA content in ZnSe nanocomposite films without any change in position of PL peak. 9. Higher intensity is obtained for smaller ZnSe particles in PVA matrix. 10. The emission may be attributed to band to band transition of which is greater than bulk band gap of ZnSe. 11. The oscillator strength is increased by reducing the size which enhances the PL intensity.
12. Due to proper passsivation of surface states non radiative transitions are not increased which enhance the PL intensity. S5 S4 S3 S2 S1
1800 1600
Intensity (a.u.)
1400 1200 1000 800 600 400 200 0 -200 440
450
460
470
480
490
500
510
Wavelength in nm
Fig.2 Photoluminescence Spectra of ZnSe/PVA Samples.
4. CONCLUSION 1. Thus ZnSe/PVA Nanocomposites can be synthesized by very simple chemical route. 2. XRD analysis revealed that, increasing PVA concentration in ZnSe/PVA, particle size is reduced. 3.
PL intensity is increased with reduction in particle size, due to enhanced oscillator strength.
4. The polymer matrix acts to stabilize the nano particle. 5. This may be useful for their potential application in anti-reflection coating, display devices and optical sensors.
6. Due to the PL peak in green and blue region these composite films are promising materials for optical display devices.
ACKNOWLEDGEMENT The authors gratefully acknowledge the valuable assistant provided by Inter University consortium (IUC) Indore for characterizing samples by XRD and also very much thankful to Department of Nanotechnology, MAINAT, Bhopal for PL Studies.
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