Structural and optical properties of nanoparticles of tetraphenyl Porphin cobalt (II) annealed thin films

Journal Pre-proof Structural and optical properties of nanoparticles of tetraphenyl Porphin cobalt (II) annealed thin films M.M. ELnahass, E. Elesh, A. Gamal

PII:

S0030-4026(19)31495-0

DOI:

https://doi.org/10.1016/j.ijleo.2019.163597

Reference:

IJLEO 163597

To appear in:

Optik

Received Date:

18 June 2019

Revised Date:

22 September 2019

Accepted Date:

11 October 2019

Please cite this article as: ELnahass MM, Elesh E, Gamal A, Structural and optical properties of nanoparticles of tetraphenyl Porphin cobalt (II) annealed thin films, Optik (2019), doi: https://doi.org/10.1016/j.ijleo.2019.163597

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Structural and optical properties of nanoparticles of tetraphenyl Porphin cobalt (II) annealed thin films M.M.ELnahassa, E.Eleshb, A.Gamalc a

Department of Physics, Faculty of Education, Ain Shams University.

bc

, Department of Physics, Faculty of Science, Port Said University.

Abstract X-ray diffraction, scanning electron microscope and infrared Spectrum

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have been used to investigate the structural characterization of CoTPP in

powder, as deposited and annealed films. The annealing effect on the crystallite size of CoTPP films, the annealing can modify the morphology of

thin films by controlling the aggregate densification of COTPP thin films.

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Some optical constants of CoTPP were studied for as deposited and films

which expose to thermal annealing. The annealing effect on optical energy

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gap, dispersion parameters, imaginary and real parts of dielectric constant. The electronic transition type is an indirect allowed transition. The values of

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optical constant were compared with the other porphyrin derivatives.

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Keywords: thin film-X ray-scanning electron microscope.optical constants

Introduction

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Microelectronics has been developed due to the new electronics

revolution [1]. Organic semiconductors have feature to conduct electricity and

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absorb light, these materials can easily to modify by chemical synthesis [2]. Organic semiconductors have many applications in organic electronics because of

the growing need to some alternative with low cost instead of

silicon, so organic semiconductors offering commercially viable technologies [3]. Porphyrins have a four-pyrrole planar macrocycle and it is peripheral decoration with groups offer additional interaction with motifs, so it is one of the most promising examples [4, 5]. porphyrins have different choice for preparation through the wide substituent to prepare the macrocycle [6, 7]. In

addition, the ligands of Porphyrin have particular interest due to their sensing, catalytic and absorption properties. All these properties can easily transfer to porphyrin derivatives and become suitable for different application in scientific fields [8,9]. Tetraphenylporphyrin belong to porphyrin family and absorbed light in a wide range of wavelengths due to  conjugated system [10]. Tetraphenylporphyrin and its substitutions thin films have been studied extensively due to their importance in electrical devices such as solar cells [11-14]. In order to have CoTPP thin film application, it is essential to understand the structural, optical and physical properties of such films. In this

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report, we discuss the structural, morphological and optical behavior of CoTPP and the effect of annealing at studied temperature on these properties; due to the lack of information on some optical parameters for annealed CoTPP thin films.

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Experimental details

5,10,15,20 tetraphenyl Porphin cobalt (II) of purity 99% was used without any further purification. CoTPP thin films of thicknesses 300 nm were prepared by

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thermal evaporation technique by using a high vacuum coating unit (Edwards Co. model E306A, England), A constant deposition rate of 2.5 nm s-1 was fixed until the

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required thickness is reached. The system was kept under vacuum for about 15 minutes before air admittance to avoid the contamination of the samples. Fused quartz and glass substrates were used for optical and structural measurements,

and 523K.

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respectively. The prepared films were annealed by dried oven for one hour at 373,473

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The structural characteristics by using Phillips X-ray diffractometer, were investigated for powder and films (as deposited and annealed).The operating voltage is 45 KV ,the current intensity is 40 mA and The scan speed is 0.005deg/second.

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The fresh powder, as-deposited and annealed films were performed using

infrared spectrophotometer with range 400- 4000 cm-1. From this, a transmittance or absorbance spectrum can be produced, showing at which the sample absorbs IR wavelengths. Analysis of these absorption characteristics reveals details about the molecular structure of the sample. The surface morphology was investigated by JEOL-JXA810 electron microscope for as deposited and annealed films. Thin film

specimens were fixed by using a very thin layer of gold on the specimens holder and sputtered (JASCO,V-570 UV-VIS-NIR) spectrophotometer used to determine the spectral behavior of the optical constants for as-deposited and annealed CoTPP thin films. Spectrophotometric method was used for measuring the optical transmittance (T) and reflectance (R), when a monochromatic light beam incident on a thin film deposited into quartz substrate, the intensity of the monochromatic light passing through the film was recorded relative to the intensity of the light having the same wavelength and passing through a clean bare reference slide of the same material as

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that of the substrate. The resultant transmittance, T was calculated according to the relation [15]. T(

I ft )(1  R q ) Iq

(1)

reference substrate, respectively and

Rq

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I Where I ft and q are the intensities of the light passing through film and

is the reflectance of quartz.

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A specular reflectance accessory with constant angle 5o was used to measure the reflectance, R, of the sample under investigation at normally incidence of the

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monochromic light. Reflectance of Aluminum mirror reference was firstly recorded in the measured range of wavelengths. Secondly, the reference of the sample is recorded in the same wavelength ranges. The resultant R was calculated according to the

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relation [16].

(2)

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I  R   fr  R m (1  [1  R q ]2 )  T 2 R q  Im 

Where I fr , I m are the intensities of light reflected from film and reference

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substrate, respectively and R m is the reflectance of the reference mirror. Results and discussion

1. Structure analysis Fig.1 shows the infrared transmission spectrum for CoTPP in powder, asdeposited and annealed thin films at 373 and 473K. The spectrum of as deposited and annealed films is quiet similar to CoTPP in powder form. CoTPP thin films have thermal stability up to the annealing temperature used, that is indicate that the thermal

evaporation is a suitable technique to obtain undissociated and stoichiometric of CoTPP films. The observed band and their assignment are listed in table.1 and nearly agreement with the previous studies [17]. Fig.2 shows X-ray diffraction patterns obtained from powder, as-deposited and annealed CoTPP thin films. XRD pattern for powder form showed various diffraction peaks indicating that material has a polycrystalline structure. Miller indices of all peaks and the lattice constants of CoTPP in powder form were calculated by using the CRYSFIRE & CHECKCELL computer programs [18]. The analysis indicates that CoTPP has the triclinic crystal system with space group (P-1) and lattice

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parameters of a=11.1610 Å, b=18.9310 Å, c=4.7160 Å, α=96.240, β=93.110 and γ=80.730. The annealed films, as shown in Fig. 2b, are partially crystallized with

preferred orientation of (2 2 0), (0 2 1) with amorphous background. Results also show that the annealing increases the integrated intensity of diffraction peaks

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corresponding to reflection planes of (2 2 0), (0 2 1) for annealed CoTPP films at 373K, 523K. Consequently, the crystallinity of thin films has been improved by

illustrated in current research.

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increasing the annealing [19], This is consistent with morphology's results which

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Fig.3 shows the morphology and grain shape for the annealed and as deposited films. The surface topography of the as-deposited film shows the granular shape of the particle with average crystallite size 45nm as shown in fig 4.a. Fig.4 (b,c) shows

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the change in the surface topography after annealing at 373K and 473K, the average of crystallite size is 83 and 126nm, respectively. It is clear; there is change in surface topography by the annealing. The higher aggregates occur on the surface of films

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which annealed at 373K and 473K more than as-deposited film. The annealing can modify the morphology of thin film by controlling the aggregate densification of

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COTPP thin film [20].

2. Optical characterization Fig.4 depicts the variation of the transmittance, T, and the reflectance, R, for

the as deposited and annealed CoTPP thin film at the range of wavelength 2002500nm. It can be observed that the intensity of the transmittance peaks within the absorption region decrease by annealing. The greatest optical reflectance peaks were observed at as-deposited film while the increasing of temperature diminishes the

reflectance.It can also be observed that transmission and reflection behaviors are the s ame before and after heat annealing for CoTPP films; in transparent region. Fig.5 shows the behavior of the refractive index, n, for as-deposited and annealed CoTPP films, which calculated from the values of T and R [21]. The behavior of the spectra reveals that the refractive index exhibits an anomalous dispersion at low wavelength and a normal dispersion at high wavelengths. There are decreasing in the values of refractive index with annealing which correlated with the decreasing of the mass density. Also, it was found a variation in the intensity of the refractive index peaks with red shift as a result of annealing [22].

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The absorption coefficient, α was computed by using the values of the transmission, T, the reflection, R and film's thickness, d, according to Eq.(3)[21].

1  (1  R)2 (1  R)4    1n   R2   d  2T 4T 2 

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(3)

Fig.6 illustrates the behavior of the absorption coefficient, α, for the both of as deposited and annealed thin films at different temperature. The absorption peaks for

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as deposited film were observed at 1.22 eV and 2.3 eV and extended with longer wavelengths with lower absorption. The other absorption peaks appeared in the UV

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region at 4.6 eV and 5.6eV, respectively. The high intense absorption, Soret band, showed at 2.76 eV, The discrete transitions beyond the Soret band are intimately associated with the presence and character of the benzene rings on the CoTPP [23,24].

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It can be observed the annealing have a slightly affect in position and intensity of the absorption coefficient peaks, may be due to the transition between bonding and anti-

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bonding molecular orbital [25].

2 Fig.7 shows ( n  1 ) as a function of the squared of photon energy according

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Wemple and DiDomenico equation [26]:

E 1 1  o  (h )2 n 1 E d Eo E d 2

(4)

The values of dispersion energy , constant at high frequency ,

Ed

, oscillator energy ,

Eo

,and dielectric

  , for the as deposited and annealed CoTPP thin films

are tabulated in table 2. Also the table contains the values of optical parameters of

some derivatives of prophyrin[17,27]. That’s values give information about the strength of inter-band optical transition inside the material [28]. Fig.8 shows the relation between the refractive index, n , and the squared of the wavelength,  , can be expressed by Eq.5[29]: ε1 = n2 = εL -

e2 N λ2 2 2 4  o m * c

(5) 

The values of the lattice dielectric constant, L , and the ratio of free carrier concentration to its effective mass,( N m * ) for the as deposited and annealed thin

and



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films at different temperature are tabulated in table 2. It is clear that the values of

 L decrease with increase temperature at measured temperature due to the lattice

vibration and bounded carrier in the transparent region decrease with the increase of

1

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the annealing temperatures [30].

2 Fig.9 shows the relation between ( h ) and photon energy ( ( h ) for the as-

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deposited and annealed films according to Bardean equation [31].The first optical

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energy gaps are called onset energy gaps E onest , corresponds to the onset of optical absorption and formation exciton[32], the second energy values are the fundamental energy gap

E fundmental

(energy gap between π-π*-band) [33].The values of optical

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energy gaps are estimated as shown in fig.10. The annealing has a significant change on examined films; both of the onset and fundamental energy gap, for as deposited and annealed films, decrease with annealing due to the dislocation of π electrons and

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the transitions between π and π*band increase[34].

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The absolute values of the optical constants n and k were used to determine

the dielectric constant

1 &  2 [35]. Fig.11 shows the spectral distribution of real and

imaginary part of dielectric constant,

1 &  2 , which called dispersion and absorption

curve due to the behavior of real dielectric constant is the same as the refractive index while the behavior of the imaginary part of dielectric constant is mainly follows the extinction coefficient, which is related to the variation of absorption coefficient with photon energy [36].

4. Conclusion X-ray diffraction technique for CoTTP and annealed thin films confirms that the material is poly crystalline with triclinic structure. The morphology for the as-deposited CoTPP depicts that the particles have granular shape and the annealing increases the particle size due to the aggregate densification of CoTPP thin films. Annealing influenced on the dispersion parameters of CoTPP film. The electronic transition type is an indirect allowed transition with onset and fundamental energy gaps of 1.51 eV and 2.41 eV, respectively. Annealing temperature influenced on both of the onset and fundamental energy gaps. The

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estimated values of ε∞ and εL decrease with increasing the temperature due to the lattice vibration and bounded carrier in the transparent region. It is clear that the increasing in annealing hasn’t radical change on optical properties of CoTPP, so

the CoTPP films are suitable to make multi-application such as solar cell due to its

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thermal stability; the manufacturing of solar cells and photovoltaic arrays has advanced considerably in recent year due to the growing demand for renewable

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lP

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energy sources.

Refrances

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[1] W. Brütting, ''Organic Semiconductors'', institute of Physics, University of Augsburg, Germany (2005).

[2] A. Köhler and H. Bässler, ''Electronic Processes in Organic Semiconductors'',

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Wiley (2015).

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[3] S. Ahmad, Journal of Polymer Engineering, 34(2018279-338.

[4] T. Balaban, Accounts of Chemical Research, 38(2005) 612–623.

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[5] R. Paolesse, C. Natale, V. Dall’Orto, A. Macagnano, A. Angelaccio, N. Motta, A. Sgarlata, J. Hurst, I. Rezzano, M. Mascini and A. D’Amico, Thin Solid Films, 354

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[6] K. Kadish, K .Smith and R. Guilard, “The Porphyrin Handbook”, Academic Press,

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San Diego (2000).

[7] S. Horn, K. Dahms and M. Senge, Journal of Porphyrins and Phthalocyanines,

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12(2008) 1053–1077.

[8] C. Zou, Z. Zhang, X. Xu, Q. Gong, J. Li and C. Wu, Catalyst", J. Am. Chem. Soc., 134(2012)87−90. [9] D. Monti, S. Nardis, M. Stefanelli, R. Paolesse, C. Natale, and A. D'Amico, Journal of Sensors,34(2009) 10.

[10]S. Chen and C.S. Liao, Macro Molecules, 26 (1993) 2810. [11] X. Huang and N. Berova, "Porphyrins and Metalloporphyrins: Versatile Circular Dichroic Reporter Groups for Structural Studies", Department of Chemistry, Columbia University (2000). [12 D. Barlow, L. Scudiero and K. Hipps, J. Phys. Chem., 20 (2004) 4413. [13] L.Xu, Z.Y. Li, W.Tan and J. He , Ch. Spectro. chem. Acta A, 62 (2005) 850.

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[14] L.Scudiero, D. Barlow and K.W. Hipps, J. Phys. Chem. B, 104 (2000) 1189. [15] L.A. Agiev and I.N. Shklyarevskii, J. Prekel Spekt, 76 (1978) 380.

[16] I.N. Shklyarevskii, T.I. Kornveeva and K.N. Zozula, Opt.Sc., 27(1969) 174.

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Optics & Laser Technology ,64(2014)28-33.

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[17] M.M. El-Nahass , F.S.H. Abu-Samaha, Shokry Menshawy and Eman Elesh ,

[18] R. Shirley, "The CRYSFIRE System For Automatic Powder Indexing",

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Guildford, Surrey GU2 7NL, England (2000).

[19] A. Hassanien, K. Aly, A. Akl, Journal of Alloys and Compounds, 685(2016)733.

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[20] J. Chou,M. Kosal,H. Nalwa,N. Rakow and K. Suslik, "Prophyrin Handbook",

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San Diiego (2000).

[21] M. Giulio, G. Micocci,R.Rella, P. Siciliano and A.Tepore, Phys. Stat .Sol., 136 (1993)101.

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[22] B. Andreas, I. Breunig and K.Buse, Chem. Phys. Chem., 98(2005)909. [23] W.R. Scheidt andY.J. Lee, Struct. Bondin, 1(1987) 64.

[24] D. Cotter, R. Manning, K. Blow, A. Ellis, A. Kelly, D. Nesset, I. Phillips, A. Poustie and D. Rogers, Non linear Optics, 286(1999)1528. [25] E.J. Baerends, G. Ricciard, A. Rosa, S.J.A. Van Gisbergen, Coord. Chem. Rev. 230 (2002) 5. [26] S.H. Wemple, M. Di Domenico, Phys. Rev., B 3 (4) (1971) 1338.

[27] M.M. El-Nahass, A.F. El-Deeb, H.S. Metwally and A.M. Hassanien, J.Appl. Phys., 52 (2010) 10403. [28] I. Solomon, M. P. Schmidt, C. Sénémaud, and M. D. Khodja, Phys. Rev.B, 38 (1988) 1326. [29] D. Edward, "Handbook Of Optical Constants Of Solids", AcademicPress Handbook, NewYork (1985). [30]M.Zhu, L.Liu, Y.Hou, H.Yan, J.B.Xu and M.Shao, X.Chen Physica, 100(2005)355.

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[31] J. Bardeen, F.J. Blatt and L. Hall, “ Proceedings of Photoconductivity Conference”, Wiley, New York (1956).

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[32] E.V.Tsiper, Z.G. Soos, W. Gao and A. Kahn, Chemical physice lecture, 360 (2002)47.

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[33] U. Zhokhavets, R. Goildhahn, G. Gobsch and W. Schliefke , Synthetic Metals,

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138 (2003)491.

[34] M.M. El-Nahass, H.M. Abd El-Khalek, and A.M. Nawar, J.Appl.Phys.,57

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(2012) 3020.

[35]K.S. Lee, T.M. Lu, C. Zhang, Microelectronics Journal, 34 (2003) 63.

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[36] M.M. El-Nahass, A.ELdeeb, A.Hassanien,The European physical journal

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applied physics,125(2011)247.

Figures

500

1000

1500

2000

2500

3000

3500

4000

120

d

100 80 60

c

100

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Transmittance%

40 120

80 60 40 120

b

100

-p

80 60 40 120

80

500

1000

lP

60 40

a

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100

1500

2000

2500

3000

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Wave number (Cm)

3500

4000

-1

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Fig.1 Infrared spectra of CoTPP for: (a) powder form, (b) as deposited film, (c) annealed film at 373K and (d) annealed film at 473K.

500

80

70

e

-

-

22 0

300

60

02 1

400

50

40

30

20

10

0

200 100 0 500 400 02 1

-

-

22 0

d

200 100 0 500

c -

-

22 0

300

02 1

400 200 100 0 500

b

400 200

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-

-

22 0

300

02 1

Intensity (count/.sec)

300

0

10

05 1

-

28 1 37 1

15 0

-

-

-

-

-

20

30

50

40

2

-p

0

a

161

100

24 0

101

200

02 1

- -

1- 2 0

300

-

400

-

- 1 1 0

0 500

22 0

100



60

70

80

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Fig.2 X-ray diffraction patterns in the form of (a) powder, (b) as deposited film ,(c)

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na

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annealed film at 373 K, (d) annealed film at 473 K and (e) annealed film at 523 K .

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-p

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lP

na

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373 K, and (c) annealed film at 473 K .

1.1 1.0

0.8

0.6

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T , R

0.7

T

na

0.9

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Fig.3 The morphology and grain shape for:(a) as deposited film ,(b) annealed film at

0.5 0.4

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0.3 0.2

R

T- as deposited T- at373 K T-at 473K T-at 523K R- aseposited R- at 373K R-at 473K R-at 523K

0.1 0.0 500

1000

1500

2000

2500

 (nm)

Fig.4 The spectral distribution of transmittance, T and reflectance, R for as deposited and annealed CoTPP thin films at different temperature.

3.4

as-deposited 373 K 473 K 523 K

3.2 3.0 2.8 2.6

n

2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 1000

1500

 (nm)

2000

2500

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500

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na

lP

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and annealed films at 373, 473 and 523K.

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Fig.5 The spectral dependence of the real part of refractive index, n, for as-deposited

Fig.6 The spectral behavior of optical absorption coefficient, α, for the as deposited and annealed CoTPP thin films.

4.0 3.5

2 -1 (n -1)

3.0 2.5

as deposited 373K 473K 523K

2.0 1.5

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1.0 0.5 0

1

2 

3

2

(h eV)

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Fig.7 The relation between (n2-1)-1 versus ( h )2 for as deposited and annealed films.

7

n2

5

4

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3

na

6

as deposited 373K 473K 523K

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2

1

0

1

2

3

2

 nm)

4

5

6

2

Fig.8 The variation of n2 versus  2 for as deposited and annealed CoTPP thin films.

as deposited 373K 473K 523K

1/2

(h) (eV/cm)

1/2

600

300

0 2

3

h

(eV)

1 2

4

5

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1

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Fig.9 The relation between ( h ) and photon energy ( ( h ) for as deposited and

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annealed CoTPP thin films.

2.6

2.2 2.0

Eonset

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1.8 1.6 1.4 1.2

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Eonset ,,Efundamental(eV)

Efundamental

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2.4

1.0

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0.8

300

350

400

450

500

T(K)

Fig.10 The variation of E onest , E fundamental as a function of annealing temperatures for as-deposited and annealed films.

550

10 9

as deposited 373K 473K 523K

a

8 7

1

6 5 4 3

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2 1 0

1

2

3

4

5

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-p

heV)

6

b 2.0

1.0

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0.5

as-deposited 373K 473K 523K

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2

1.5

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2.5

0.0

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1

2

3

4

5

6

heV)

Fig11: a. The spectral distribution of ε1 for the as deposited and annealed CoTPP thin films, b. The Spectral distribution of ε2 for the as deposited and annealed thin films at different temperature.

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Table Tables

Table.1 Assignments of CoTPP spectrum in powder form, as-deposited and annealed thin films at different temperature. As -deposited Annealed at Annealed Powder Assignments film 373K at 473K

(1596.51537.5)

1348.5

1350.0

(1204.11070.5)

1071.73)

1049

1049.47

1003.2

1004.7

1176.4

-

794.7

796.5

2921

1598.07

1598

1634.9

1634

1070

1072

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ν(C-H)(aromatic) ν(C-H)sym. in CH3

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(1678.31539.2)

2921.3

1093

-p

2852.6

3420

1004

1004

1073

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2842.37

3415

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(3053.13023.7)

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(3050.83022.1)

ν(C=C) ν(C-N)

ᵟ (C-H) bend ν( C-O) ν (Pyr- breathing)

-

-

δ (Cβ-H) C-H bend in phenyl

796

795.83

ᵞ(C-H) ᵞ (porphyrin)

Table2:The optical parameters for as-deposited and annealed CoTPP,FeTPPCl and CuTPPthin films[17,27]. film conditions

T(K)

Eo

Ed



εL

56 ( N m * )x10

(K g-1 .m-3)

(eV) (eV) 298

4.5

11.9

3.6

3.77

1

CoTPP Annealed

373

5.9

7.1

2.18

2.26

0.4

473

5.8

5.3

1.9

1.98

0.2

523

6

1.8

1.3

1.321

0.1

FeTPPCL As-deposited

298

1.82

5.7

4.05

4.9

1.94

FeTPPCL Annealed

423

1.93

5.4

3.83

473

2.02

5.2

3.6

523

2.1

5

3.4

298

2.26

7.9

4.32

453

3.77

9.6

3.52

3.69

1.11

503

6.26 13.8 3.22

3.35

0.742

523

8.57 17.9 3.09

3.24

0.738

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4.6

2.05

4.1

2.07

3.9

2.17

4.40

2.56

-p

CuTPP Annealed

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CuTPP As-deposited

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CoTPP As-deposited