Basic and Applied Research
(IJSBAR)
ISSN 2307-4531
(Print & Online)
http://gssrr.org/index.php?journal=JournalOfBasicAndApplied
---
Study Optical Properties of PVP Films Doped with
Nanoparticles Ag by Using Nd:YAG Laser
Zahraa N. Salman
a*, Faisal A. Mustafa
b, Riydh N. Ali
ca laser Physics Department/College of Science for Women/Babylon University, 80 street ,Hilla 00964, Iraq blaser Physics Department/College of Science for Women/Babylon University, Aljazaer ,Hilla 00964, Iraq claser Physics Department/College of Science for Women/Babylon University, Almusaib ,Hilla 00964, Iraq
aE-mail:[email protected] bE-mail:[email protected]
Abstract
The doped PVP with nanoparticle silver metal using Nd:YAG laser ablation solute in ethanol. The spin-coating techniques with concentrations (0,3,5,7,9,11wt%) are achieved by (20 ml ) ethanol using magnetic stirrer The solution doped with (1ml) of collide nanosilver particle.. An increment of UV-Vis absorption has produced maximum peak absorbance spectra at about 0.7 to 0.85 values with a high shifting after doping with nanoparticle silver. The indirect Egopt of pure and doped PVP films were found to be decreased about
2.56,2.54,2.52.2.50,2.47eV, and 4.18,4.14,4.15,4.16,4.12,4.17 eV for indirect allowed transitions as increase concentration respectively, whereas the indirect forbidden band gaps were determined as 2.73, 2.67, 2.66, 2.65, 2.63 eV and 4.175,4.18,4.15,4.158,4.1,4.165 eV with increase concentration after doping respectively. The prepared samples appeared near band edge peak absorption at about 350 nm.
Keywords: polyvinylpyrrolidone (PVP); doping; structural; optical properties; optical energy gap; concentration; nanoparticle silver.
--- * Corresponding author.
E-mail address: [email protected]
1. Introduction
PVP was first synthesized by Walter Rappe and Patent was filed in 1939 for one of the most interesting derivatives of acetylene chemistry [1]. PVP was initially used as a blood plasma substitute and later in a wide variety of application in medicine, pharmacy, cosmetics and industrial production. PVP is soluble in water and other polar solvents. When dry it is a light flaky powder, which may absorbs up to 40% of its weight in atmospheric water .In solution, it has excellent wetting properties and readily forms film. This makes it good as a coating or an additive to coatings [2]. The authors in [3] Collide Au and polyvinylpyrrolidone composite thin film are fabricated by spin – coating to study the nonlinear optical properties of Au / PVP composite thin film. The authors in [3] studied the synthesis and characterization of (Ag/PVP) Nanoparticles using Gamma Irradiation Techniques. The authors in [4] studied the synthesis, structural and optical properties of PVP encapsulated CdS Nanoparticles. The authors in [5] studied the structural and optical properties of Li + : PVP and Ag+ : PVP polymer films.
2. Experimental
PVP solution was prepared with different weight percentage (0 , 3 , 5 , 7 , 9 , 11%) . PVP was dissolved in a glass screw cup in (20 ml ) ethanol using magnetic stirrer . The solution doped with (1ml) of colloid nanosilver particle. This colloidal solution was prepared by using second harmonic generator of Nd:YAG laser (532 nm). The samples were put on glass substrate to obtain a film by using spin coating technique under atomic pressure and (3000 r/min), the thickness of the film about (5 μm). A(UV-Vis spectrophotometer (UV-Vis-CECIL2700) was used to get the spectral absorbance and transmittance at room temperature.
3. Theoretical
The relationship between incident intensity and the penetrating light intensity is given by equation:
Where t is the thickness of the matter (cm) and α is the absorption coefficient (cm-1) [7]:
Where the amount of log I/Io represents the absorbance (A).The absorption coefficient can be calculated by:[8]
If the amount of absorption is α≥104cm-1, the electronic transitions are direct. The amount of optical energy gap from this region can be evaluated by the relation [9]:
I=Ioe-αt (1)
α t =2.303 log Io / I (2)
α = 2.303 (A/t) (3)
α hυ= A(hυ-Eg)m (4)
Where hυ is the photon energy, A is the proportional constant, Eg is the allowed or forbidden energy gap of
direct transition and m is a parameter that gives the type of electron transition. Specifically, m is ½ ,3/2,2,and 3 for transitions direct allowed, direct forbidding, indirect allowed and indirect forbidding respectively [10]. The indirect transition, which requires phonon assistance, the absorption coefficient has the following dependence on photon energy [11]:
Where Ep is the energy of the photon associated with the transition, A and B are constants, depending on band
structure. The optical absorption edge can be correlated to optical gap energy using Taucs equation [12]. The variation of lnα as a function of photon energy is given by:
Where Eu is the Urbarch energy, it can be evaluated as width of the localized states. The optical band gap can be obtained by extrapolating the linear portion of plot (αhυ)1/n versus hυ to α =0. The refraction index consists of real and imaginary parts (N= n-ik), the relation between reflectivity and refractive index is given by the equation [13]:
Where k is the extinction coefficient. The quality (R+T<1) at certain wavelength implies the existence of absorbing region. The refractive index can be expressed by the equation [14]:
The extinction coefficient can be calculated by using the equation [15]:
Where λ is the wavelength of the incident ray. The relation between the complex dielectric constant and the complex refractive index N is expressed by:
We can conclude that [16]:
2 2
(
)
)
(
h
E
gE
pB
h
E
gE
pA
h
υ
=
υ
−
+
+
ν
−
−
α
(5))
exp(
u oE
h
ν
α
α
=
(6) 2 2 2 2)
1
(
)
1
(
k
n
k
n
R
+
+
+
−
=
(7)
) 1 ( ) 1 ( ) 1 ( 4 2 2 − + − − − = R R R k R n (8)π
αλ
4
=
k
(9) ε=N2 (10) (n-ik)2=ε1-iε2 (11) 151The real and imaginary complex dielectric constant can be expressed by the following two equations respectively:
Also the finesses coefficient is given by [6]:
The optical conductivity is related to light speed and can be expressed by the equation [17]:
4. Results and Discussion
The experimental results show that there are differences in optical parameters before and after doping with silvers nanoparticle in two preparations volume percentages. Figure (1) shows the optical absorbance as a function of wavelength at different concentrations of PVP thin film. The absorbance increases as concentrations increasing, because the polymer chains fill the vacancies of the real solution, but when doped with nanoparticle silver, the position of the absorbance are shifted to the red side, the absorbance increased and another weaker
peak appeared at 680nm wavelength as shown in Figure (2). .
Figure1: The spectral absorbance at different concentrations of PVP thin film.
0.3
0.4
0.5
0.6
0.7
0.8
330
380
430
480
530
580
630
680
Wavelength (nm)
A bs or banc e *10 ^ -1 3% 5% 7% 9% 11% ε1=n2-k2 , ε2=2nk (12) 2 ) 1 ( 4 R R F − = (13)π
α
σ
4 . nc opt = (14) 152
Figure 2: The spectral absorbance at different concentrations of PVP doped Ag thin film.
Figure 3 shows the spectral reflectance at different concentrations of PVP thin film. The position of the reflectance are shifting to the greatest wavelength as doping with nanoparticle silver as shown in Figure 4. The reflectance increase as the polymer solution contains nanoparticle silver. The intensity peak width increase after doping. So a simple change in structure of polymer after addition of dopant with roughly doping and concentration. This is because the filling Ag nanoparticle (5% , volume ratios) with the chain polymer. The free radicals will combine with silver ions. Combined there is a simple change in the structure of polymer has chemically occurred [17].
Figure 3: The spectral reflectance at different concentrations of PVP thin film.
0.336
0.436
0.536
0.636
0.736
0.836
0.936
330
380
430
480
530
580
630
680
wavelength (nm)
A bs or banc e *10 ^ -10%
3%
5%
7%
9%
11%
0.06 0.07 0.08 0.09 0.1 0.11 0.12 0.13 0.14 0.15 330 380 430 480 530 580 630 680Wavelength (nm)
R ef lec tanc e 3% 5% 7% 9% 11% 153Figure 4: The reflectance at different concentrations of PVP doped Ag thin film.
Fig. 5 shows spectrum as a function of an optical transmittance films. The increased of PVP concentrations decrease the transmittance, because of the occupancy of the vacancies between the polymer chains. Fig.6 shows the decreasing of transmittance after doping with nanoparticles silver, the silver ions will occupy the residual positions of polymer chains especially at the shortest wavelengths.
Figure 5: The spectral transmittance at different concentrations of PVP thin film.
Figure 6: The transmittance at different concentrations of PVP doped Ag thin film. 0.067 0.087 0.107 0.127 0.147 330 380 430 480 530 580 630 680 Wavelength (nm) R ef lec tanc e 0% 3% 5% 7% 9% 11% 0.82 0.84 0.86 0.88 0.9 0.92 330 380 430 480 530 580 630 680 Wavelength (nm) T rans m it anc e 3% 5% 7% 9% 11% 0.801 0.821 0.841 0.861 0.881 0.901 330 380 430 480 530 580 630 680 Wavelength (nm) T rans m itanc e 0% 3% 5% 7% 9% 11% 154
The absorption coefficient also increases as photon energy increases slightly and the peak of this factor is 3.65 eV value. The absorption coefficient increases with increasing the concentration. This is depended on the absorbance value as shown in Figure 7 .But after doping with nanoparticle silver, there are shifting in peaks of the higher absorption coefficients as shown in Figure 8 .The absorption coefficients increase to 0.9 after doping. This can be used in solar cells
Figure 7: The absorption coefficient as a function of photon energy at different concentrations of PVP thin film.
Figure 8: shows the absorption coefficient as a function of photon energy at different concentrations of PVP doped nanoparticle Ag thin film.
Figures.9 and 10 show the extinction coefficient as a function of wavelength at different concentrations of PVP before and after doped thin film with nanoparticle silver contained by laser. The peaks is higher after doping at 355 and 680 nm.
Figures 11 and 12 show refractive index as a function of wavelength at different concentrations of PVP before and after doping thin film. The refractive indices decrease with wavelength increase.
0.02 0.04 0.06 0.08 0.1 0.12 0.14 1.5 2 2.5 3 3.5 4
Photon energy (eV)
A bs or bt ion c oeef fi c int *10 ^ 1 ( c m -1 ) 3% 5% 7% 9% 11% 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.5 2 2.5 3 3.5 4 4.5
Photon energy (eV)
A bs or bt ion c oef fi c int *10 ^1 (c m -1 ) 0% 3% 5% 7% 9% 11% 155
Figure 9: Extinction coefficient as a function of wavelength at different concentrations of PVP thin film.
Figure 10: Extinction coefficient as a function of wavelength at different concentrations of PVP doped nanoparticle Ag thin film.
Figure 11: Reflective index as a function of wavelength at different concentrations of PVP thin film.
0.24 0.26 0.28 0.3 0.32 0.34 0.36 330 380 430 480 530 580 630 680 Wavelength (nm) E x ti c ti on c oef fi c int * 10 ^-5 3% 5% 7% 9% 11% 0.25 0.3 0.35 0.4 330 380 430 480 530 580 630 680 Wavelength (nm) E x ti nc ti on c oef fi c int *10 ^-5 0% 3% 5% 7% 9% 11% 0.107 0.108 0.109 0.11 0.111 0.112 0.113 0.114 0.115 0.116 330 380 430 480 530 580 630 680 Wavelength (nm) R ef rac ti v e i ndex * 10 3% 5% 7% 9% 11% 156
Figure 12: Refractive index as a function of wavelength at different concentrations of PVP doped Ag thin film.
Figures 13 and 14 show real dielectric coefficient as a function of wavelength at different concentrations of pure PVP and doped thin film with nanoparticle silver. The real dielectric coefficient increase after doping, because of the combing of silver nanoparticl with polymer bonds.
Figure 13: Real dielectric coefficient as a function of wavelength at different concentrations of PVP thin film.
Figure 14: Real dielectric coefficient as a function of wavelength at different concentrations of PVP doped Ag thin film. 0.1066 0.1086 0.1106 0.1126 0.1146 0.1166 330 380 430 480 530 580 630 680 Wavelength (nm) R ef rac ti v e i ndex *10 ^ 1 0% 3% 5% 7% 9% 11% 0.1141 0.1191 0.1241 0.1291 0.1341 330 380 430 480 530 580 630 680 Wavelength (nm) R eal D iel ec tr ic c oef fi c int * 10 ^1 3% 5% 7% 9% 11% 0.114 0.119 0.124 0.129 0.134 0.139 330 380 430 480 530 580 630 680 Wavelength (nm) R eal D iel ec tr ic coef fic int *10 ^1 0% 3% 5% 7% 9% 11% 157
Figures 15 and 16 show imaginary dielectric coefficients as a function of wavelength at different concentrations of PVP before and after doping thin film.
Figure 15: Imaginary dielectric coefficient as a function of wavelength at different concentrations of PVP thin film.
Figure 16: shows imaginary dielectric coefficient as a function of wavelength at different concentrations of PVP doped Ag thin film.
Figures 17 and 18 show (αhʋ)1/2 as a function of photon energy at different concentrations of PVP before and after doping thin film for allowed energy.
Figure 17:(αhʋ)1/2 as a function of photon energy at different concentrations of PVP thin film.
0.55 0.6 0.65 0.7 0.75 0.8 330 380 430 480 530 580 630 680 Wavelength (nm) Im agi nar y D iel ec tr ic c oef fi c int * 10 ^-5 3% 5% 7% 9% 11% 0.56 0.61 0.66 0.71 0.76 0.81 0.86 330 380 430 480 530 580 630 680 Wavelength (nm) Im agi nar y D iel ec tr ic coef fic int *10 ^-5 0% 3% 5% 7% 9% 11% 0.02 0.07 0.12 0.17 0.22 0.27 1.5 2 2.5 3 3.5 4
Photon energy (eV)
(α hʋ ) 1/ 2 (cm -1 . eV )^ 1/ 2* 10 ^-1 2.50% 5% 7% 9% 11% 158
Figure 18: (αhʋ)1/2 as a function of photon energy at different concentrations of PVP doped Ag thin film. Figs 19 and 20 show (αhʋ)1/3as a function of photon energy at different concentrations of PVP before and after
doping thin film with nanoparticles silver. The forbidden energy gap is high after doping because the silver ions capture electrons
Figure 19: (αhʋ)1/3 as a function of photon energy at different concentrations of PVP thin film.
Figure 20:(αhʋ)1/3 as a function of photon energy at different concentrations of PVP doped Ag thin film.
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 1.5 2 2.5 3 3.5 4 4.5
Photon energy (eV)
(α hʋ ) 1/ 2 (cm -1 .eV )^ 1/ 2* 10 ^-1 0% 2. 5% 5% 7% 9% 11% 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16
1.5 2 2.5Photon energy (eV) 3 3.5 4
(α hʋ ) 1 /3 ( cm -1.eV )^ 1/ 3 *10 ^ -1 2.50% 5% 7% 9% 11% 0 0.2 0.4 0.6 0.8 1 1.2 1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5
Photon energy (eV)
(α h ʋ ) 1 /3 ( cm -1 . eV )^ 1/ 3 *10 ^ -1 0% 2 .5% 5% 7% 9% 11% 159
Figure 21: The dependence of Eg on doping levels for allowed and forbidden Indirect transitions of PVP thin film
Figure 22: The dependence of Eg on doping levels for allowed and forbidden indirect transitions of PVP doped Ag thin film.
Figures 23 and 24 show finesses coefficient as a function of wavelength at different concentrations of PVP thin film before and after doping with nanoparticle silver.
Figure 23: Finesses coefficient as a function of wavelength at different concentrations of PVP thin film.
2.2 2.3 2.4 2.5 2.6 2.7 2.8 0 2 4 6 8 10 12 c% Eg ( eV)
f orbidden indirect transition *10 allow ed indirect transition*10
4.08 4.1 4.12 4.14 4.16 4.18 4.2 0 2 4 6 8 10 12 c% E g( eV )
forbidden indirect transition*10
allowed indirect transition *10
0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 330 380 430 480 530 580 630 680 Wavelength (nm) F inees s e c oef fi c int 3% 5% 7% 9% 11% 160
Figure 24: Finesses coefficient as a function of wavelength at different concentrations of PVP doped Ag thin film.
Figures 25 and 26 show optical conductivity as a function of wavelength at different concentrations of PVP before and doped Ag thin film.
Figure 25: Optical conductivity as a function of wavelength at different concentrations of PVP thin film.
Figure 26: Optical conductivity as a function of wavelength at different concentrations of PVP doped Ag thin film. 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 330 380 430 480 530 580 630 680 Wavelength (nm) F inees s e c oef fi c int 0% 3% 5% 7% 9% 11% 0.138 0.188 0.238 0.288 0.338 330 380 430 480 530 580 630 680 Wavelength (nm) O pt ic al c ondec ti v it y *10 ^8 3% 5% 7% 9% 11% 0.13 0.18 0.23 0.28 0.33 0.38 330 380 430 480 530 580 630 680 Wavelength (nm) O pt ic al c ondec tiv ity *10 ^8 0% 3% 5% 7% 9% 11% 161
Figures 27 and 28 show the spectrum peaks as a function of concentrations of PVP doped Ag thin film.
Figure 27: The spectrum peaks as a function of concentrations of PVP thin film.
Figure 28: The spectrum peaks as a function of concentrations of PVP doped Ag thin film.
5. Conclusions
The results describe that the optical properties has a maximum values at 350nm and the absorbance values is higher after increase concentration of polymer and doping with nanoparticle silver. The other parameters change after doped with nanosilver by using laser.
References
[1] Fischer, Frank; Bauer, Stephan . "Polyvinylpyrrolidon. Ein Tausendsassa in der Chime", Chime in insurer Zeit, vol: 43 (6): pp376–383 ,2009
[2] Shen hong ,cheng bo-lin ,lu guo wie ,wang wei tian ,Guangdong –yi, chen zheng-hao and yang guo-zhen "Nonlinear optical properties of Au/PVP composite thin films" Chinese physics vol 14 no9,pp1915-1918, September 2005 0 0.2 0.4 0.6 0.8 1 0 2 4 6 8 10 12 c% S pec tr um peak s Absorbtion*10^-1 Transition Reflectance Exitinction coeff*10^-5 Refractive index *10 Fineesse coff 0 0.2 0.4 0.6 0.8 1 0 2 4 6 8 10 12 c% S pec tr um peak s Absorbtion*10^-1 Transition Reflectance Exitinction coeff*10^-5 Refractive index *10 Fineesse coff 162
[3] Shawkat Salameh Gasaymeh1, Shahidan Radiman1, Lee Yook Heng2 Elias Saion3 and G. H. Mohamed Saeed1."Synthesis and Characterization of Silver/Polyvinilpirrolidone (Ag/PVP) Nanoparticles Using Gamma Irradiation Techniques ", American Journal of Applied Sciences, vole 7(4):pp 500-508, 2010
[4] L. Saravanan1,*, S. Diwakar2, R. Mohankumar2, A. Pandurangan3 and R. Jayavel1 ."Synthesis, Structural and Optical Properties of PVP Encapsulated CdS Nanoparticles", INTECH OPEN ACCESS PUBLISHER , Vol. 1, No. 2,pp 42-48, 2011. .
[5]Kothapalle Sivaiah*, Koramala Naveen Kumar, V. Naresh, Srinivasa Buddhudu ."Structural and Optical Properties of Li+:PVP& Ag+:PVP Polymer Films", Materials Sciences and Applications, vole 2,pp 1688-1696,2011.
[6]. Neama, H. "The electrical and Optical Properties of Polystyrene – FeCl 3 Composites", MSc. Thesis, Babylon University, College of Science,2012.
[7]. Klingshirn, C. "Semiconductor Optics", Verlag Berlin Heidelberg, New York,1997.
[8] J. Michael Hollas ,"MODERN SPECTROSCOPY ", The Atrium, Southern Gate, Chichester, West Sussex PO19 8SQ, England,1988,p305
[9]. Kolinko, M.O. & Bovgyra, O.V.. 'Calculation of the Spectra of Characteristic of Electron Losses in Indium Bromide (1976)". J.Semi .Phys , vol10(3), pp19-22,2007.
[10]. Thutupalli, G.M. & Tomlin, G. J.Phy. D: Appl. Phys.,vol 9. 1963.
[11]. Tauce, J. J. of Non-Crystalline Solids, pp569-585. (1972).
[12]. Chiad, S. " Optical and Structural Properties of(SnO 2 ) Doped by Fluorine Irradiated by Gamma Rays", M.Sc. Thesis, College of Science for Women, Baghdad University, (2005).
[13]. Wyckoff, (1963). "Crystal Structure". Vol1, New York: Wiley.
[14]. Sze, S. & Kwok, Ng. "Physics of Semiconductor Devices", 3rd Ed. (2006).
[15]. Mohammed, M. "Effect of Preparation Conditions on the Structural and Optical Properties of TiO 2 Thin Films Deposited by Pulsed Laser Techniques", M.Sc., Thesis, n Babylon University, College of Science. (2010).
[16]. John, R., Aron, S., Jason, D. & Elizabeth, C. Lmnol.Occanogr, vol 53(3), pp955-969, (2008).
[17]. Dahshan, M. "Introduction to Material Science and Engineering" (2 nd Ed.),pp434, (2002) .
