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Synthesis and characterization of CuInS2 quantum dot in the presence of novel precursors and its application in dyes solar cells
Materials Letters ∎ (∎∎∎∎) ∎∎∎–∎∎∎
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Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
Synthesis and characterization of CuInS2 quantum dot in the presence of novel precursors and its application in dyes solar cells Mehdi Mousavi-Kamazani, Masoud Salavati-Niasari n, S.Mostafa Hosseinpour-Mashkani, Mojgan Goudarzi Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P. O. Box. 87317-51167, Islamic Republic of Iran
art ic l e i nf o
a b s t r a c t
Article history: Received 23 December 2014 Accepted 19 January 2015
In this work, CuInS2 (CIS) quantum dot was successfully synthesized with the aid of carminic acid–Cu(II) as a novel copper precursor and thioglycolic acid (TGA( as a capping agent, sulfide source, and reducing agent in order to reduce Cu2 þ to Cu þ by a hydrothermal method. Carminic acid extracted from cochineal dye to synthesize copper precursor. Furthermore, in order to investigate the effect of different dyes and CIS-QDs on the solar cell yield, several experiments were performed. & 2015 Published by Elsevier B.V.
Keywords: CuInS2 Nanoparticles Solar energy materials Electron microscopy Natural dye
1. Introduction
2. Experimental
CuInS2 a critical semiconductor with a direct band gap of 1.5 eV is considered to be an efficient light absorbing semiconductor material for application in photovoltaic solar cells [1]. It is also known that the quantum dot CuInS2 can form a barrier layer on the nanocrystal TiO2 film, which can improve solar cells efficiency [2]. Over the past decades, considerable effort has been focused on synthesizing of CuInS2 through a solvothermal, solution–chemical method, and so on [1]. To the best of authors' knowledge, little is known about the synthesis of CuInS2 nanostructures by the hydrothermal method because it is hard to find a suitable reducing agent to reduce Cu2 þ to Cu þ in water. We suggest carminic acid–Cu(II) as a novel copper precursor to synthesize CuInS2 quantum dot through the hydrothermal technique based on utilizing TGA as a capping agent, sulfide source, and suitable reducing agent for reducing Cu2 þ to Cu þ . Furthermore, copper precursor was synthesized by extracting carminic acid from cochineal dye. The principal component of cochineal dye is carminic acid. Numerous natural dyes were applied as potential candidates in DSSC since ruthenium dyes, like N719, are very expensive and environmentally toxic. Therefore, we used Cu2 þ in order to synthesize the carminic acid–Cu(II) complex from the cochineal dye. Finally, the energy conversion efficiencies were investigated through several photovoltaic tests.
Materials and characterization: All the chemical reagents were of analytical grade and were used as received without any further purification. The FTO-TiO2 and FTO-TiO2/CIS/Pt-FTO structures were prepared as mentioned in the literature [3]. Cochineal dye was obtained from the dried bodies of female scale insects species, Dactylopius coccus, which feed on wild cacti. The XRD patterns were collected from a diffractometer of Philips Company with X’pert promonochromatized Cu Kα radiation (λ¼ 1.54 Å). A LEO 1455VP scanning electron microscope (SEM) was used to investigate the morphology of the products. TEM image was taken on an EM208S Philips transmission electron microscope with an accelerating voltage of 100 kV. Fourier transform infrared (FT-IR) spectra were recorded on Magna-IR, spectrometer 550 Nicolet with 0.125 cm 1 resolution in KBr pellets in the range of 400–4000 cm 1. Photocurrent density–voltage (J–V) curve was measured by using computerized digital multimeters (Ivium-nStat Multichannel potentiostat) and a variable load. A 300 W metal xenon lamp (Luzchem) served as a simulated sun light source, and its light intensity (or radiant power) was adjusted to simulated AM 1.5 radiation at 100 mW/cm2 with a filters for this purpose. Preparation of the carminic acid–Cu(II) complex: At first, 0.2 g of CuSO4 5H2O was dissolved in 20 ml of distilled water. Then, 1 g of cochineal dye was dissolved in 20 ml of distilled water and filtered through a smooth paper and gradually added into the above solution under magnetic stirring. The mixture was stirred and heated at 60 1C for 2 h. After thermal treatment, the system was maintained to cool down to room temperature, and the resulting precipitates were collected. Finally, it was washed with absolute ethanol and distilled
n
Corresponding author. Tel.: þ 98 31 55912383; fax: þ 98 31 5555 29 30. E-mail address: [email protected] (M. Salavati-Niasari).
http://dx.doi.org/10.1016/j.matlet.2015.01.076 0167-577X/& 2015 Published by Elsevier B.V.
Please cite this article as: Mousavi-Kamazani M, et al. Synthesis and characterization of CuInS2 quantum dot in the presence of novel precursors and its application in dyes solar cells. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2015.01.076i
67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101
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Fig. 1. Schematic diagram formation of (a) carminic acid–Cu(II) complex, (b) successive adsorption CIS-QD along with dye on the FTO-TiO2, (c) FT-IR spectra of carminic acid–Cu(II) complex and (d) CIS-QD.
water and was dried in vacuum at 80 1C for 10 h (Fig. 1a). CIS-QD was synthesized according to the following procedure: 1 mmol of carminic acid–Cu(II) and 1 mmol of InCl3 were dissolved in 40 mL of distilled water and stirred for about 10 min. Then, 10 mL of TGA was added drop wise into the above solution under magnetic stirring. Finally, the solution was sealed into 150 ml Teflon-lined stainless steel autoclave and heated at 140 (sample 1), 170 (sample 2), and 200 1C (sample 3) for 10 h. In order to investigate the effect of the TGA concentration, an experiment was performed in presence of 20 ml TGA (sample 4). Fabrication of FTO-TiO2/CIS-QD/cochineal dye/Pt-FTO: The autoclave, containing CIS precipitate, was cooled to room temperature naturally and the obtained precipitate was stirred hardly for 5 min. Afterwards, as prepared FTO-TiO2 structure [3] was put into the above precipitate for 10 h. Therefore, as-produced CIS-QD along with the dye subsidence on the FTO-TiO2 were made and washed with distilled water (Fig. 1b). Counter-electrode was made from deposition of a Pt solution on FTO glass. Afterwards, this electrode was placed over FTO-TiO2/CIS/dye electrode. Sealing was accomplished by pressing the two electrodes together on a double hot-plate at 110 1C. The redox electrolyte consisting of 0.05 M of LiI, 0.05 M of I2, and 0.5 M of 4-tert-butylpyridine in acetonitrile as a solvent was introduced into the cell through one of the two small holes drilled in the counter-electrode. Finally, these two holes were sealed by a small square of sealing sheet and characterized by a J–V test.
3. Results and discussion The FT-IR spectra of the carminic acid–Cu(II) precursor and the CIS quantum dot obtained at 200 1C in presence of 10 ml TGA (sample 3) are shown in Fig. 1c and d, respectively. The absorption
bands at 3434 and 1622 cm 1 could be attributed to the & (OH) stretching and bending vibrations, respectively. Moreover, the absorption peak at 503 cm 1 is due to Cu–O bond [4]. Furthermore, the absorption peak at 1334 cm 1 corresponds to –COOH symmetry stretching vibrations, while absorptions at 2925 and 824 cm–1 are related to stretching and bending vibrations of C–H bond, respectively. Fig. 1d shows the FT-IR spectrum of the CIS-QD (sample 3). Since the curve under this condition has no absorption peaks, pure CIS-QD was synthesized without any organic impurities. Fig. 2a–e illustrates the SEM and TEM images of the CIS 1–4 samples, respectively. Fig. 2a suggests that the product is mainly composed of a large amount of agglomerated nanoparticles. By increasing the reaction temperature to 170 1C (sample 2), the product consists of nanoparticles and nanosheets, as shown in Fig. 2b. By further increasing the reaction temperature to 200 1C while keeping the reaction time constant at 10 h (sample 3), the product is composed of small nanoparticles, as shown in Fig. 2c. Based on Fig. 2d, the morphology of the CIS in presence of 20 ml TGA (sample 4), product is composed of agglomerated nanoparticles. According to the TEM image of the CIS (sample 3, Fig. 2e), the particle size of the product is between 8 and 12 nm. Comparison of XRD patterns of 1–4 samples are shown in Fig. 3a–d, respectively. The XRD patterns of CIS (sample 1 and 2 at 140 and 170 1C, Fig. 3a and b) indicate the formation of CIS along with Cu2S, CuS, In2S3, S, and In2O3. By increasing the reaction temperature to 200 1C, pure tetragonal CuInS2 (space group I-42d, JCPDS no. 38-0777) with cell constants a ¼5.5200, b¼5.5200, and c¼ 11.1200 nm was obtained (sample 3, Fig. 3c). The XRD pattern of the as-synthesized product in presence of 20 ml TGA is shown in Fig. 3d, which indicates the product is composed of CIS, Cu2S, and CuS phases. In order to compare the effect of the adsorption mode on TiO2 surface on the
Please cite this article as: Mousavi-Kamazani M, et al. Synthesis and characterization of CuInS2 quantum dot in the presence of novel precursors and its application in dyes solar cells. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2015.01.076i
67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132
M. Mousavi-Kamazani et al. / Materials Letters ∎ (∎∎∎∎) ∎∎∎–∎∎∎
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Fig. 2. SEM images of (a) sample 1, (b) sample 2, (c) sample 3, (d) sample 4 and (e) TEM image of sample 3.
harvesting of light over a wide range of wavelengths, several tests were performed. The photovoltaic parameters obtained by measuring J–V curves (Fig. 3e and f) are shown in Table 1. The energy conversion efficiencies of the single-dye-sensitized solar cells using N719, CIS-QD, cochineal, and CIS-cochineal were 3.03, 0.12, 0.47, and 0.78%, respectively. Obviously a remarkable enhancement in efficiency takes place for the mixture of dye-nanoparticles compared to the pure dye or nanoparticles. This enhancement is the result of barrier layer formation by nanoparticles which in turn increases electron lifetime [2]. Furthermore, according to the Fig. 2, the obtained CuInS2 layers on TiO2 are nanograined and contain, therefore, both developed a very crystal/crystal interfaces as well as free surfaces with extremely high specific area which could be another reason for increasing solar cell yield in the presence of CuInS2 layers on TiO2. It has been recently demonstrated that the physical properties of pure and doped nanograined materials are strongly dependent on the presence of defects like interphase boundaries and grain boundaries on the presence of doping atoms in the (invisible for XRD) amorphous surficial, interfacial and intergranular layers [5,6]. The related reaction to form stoichiometric CuInS2 during hydrothermal process might be given in Eq. (5). Cu2 þ þ 2HSCH2COOH-Cu(HS)2 þ2CH2COOH þ
(1)
2Cu(HS)2-Cu2Sþ …
(2)
In3 þ þ3HSCH2COOH-In(HS)3 þ3CH2COOH þ
(3)
In(HS)3-In2S3 þ…
(4)
Cu2Sþ In2S3-2CuInS2
(5)
In comparison with similar works, the current work is easier to control and more affordable. In this study, thioglycolic acid was used instead of polyol solvents as a reducing agent to reduce of Cu2 þ to Cu þ and this product (CuInS2) can be easily synthesized in aqueous media. Besides, carminic acid was extracted from cochineal dye by Cu2 þ and new copper precursor was obtained and its using has many advantages such as: no need to any surfactant, possibility of single step production of three layered solar cells, presentation of a comprehensive method to increase of longevity of natural dyes etc.
4. Conclusions CuInS2 quantum dots were successfully synthesized through the hydrothermal method of carminic acid–Cu(II) complex and TGA as new precursors. The XRD results indicated that pure tetragonal CIS could only be obtained in the reaction temperature of 200 1C for 10 h. Furthermore, a single and double layer of the different dyes as sensitizers were successfully adjusted on TiO2 surface nanoparticles. The energy conversion efficiency of QD-dye adsorption is high (CIS-cochineal, 0.78) because the formation of CIS barrier layer is more than single-dye adsorption (cochineal, 0.47) on the TiO2 electrode.
Please cite this article as: Mousavi-Kamazani M, et al. Synthesis and characterization of CuInS2 quantum dot in the presence of novel precursors and its application in dyes solar cells. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2015.01.076i
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M. Mousavi-Kamazani et al. / Materials Letters ∎ (∎∎∎∎) ∎∎∎–∎∎∎
Fig. 3. XRD patterns of (a) sample 1, (b) sample 2, (c) sample 3, (d) sample 4 and photocurrent–voltage curves of DSSCs adsorbed with (e) N719, and (f) CIS, cochineal and CIS-cochineal.
Please cite this article as: Mousavi-Kamazani M, et al. Synthesis and characterization of CuInS2 quantum dot in the presence of novel precursors and its application in dyes solar cells. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2015.01.076i
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Table 1 Energy conversion efficiency of DSSCs adsorbed with a: N719, b: CIS, cochineal and CIS-cochineal dye. Dyes
Voc (V)
Jsc (mA/cm2)
FF
η (%)
N719 CIS-QD Cochineal CIS-Cochineal
0.75 0.52 0.64 0.62
9.7 0.494 1.21 1.94
0.42 0.47 0.61 0.65
3.03 0.12 0.47 0.78
5
References [1] Zhou J, Li S, Gong X, Yang Y, Guo Y. Mater Lett 2011;65:2001–3. [2] Guo F, He J, Li J, Wu W, Hang Y, Jianli. H. J Colloid Interface Sci 2013;408:59–65. [3] Panahi-Kalamuei M, Mohandes F, Mousavi-Kamazani M, Salavati-Niasari M, Fereshteh Z, Fathi M. Mater Sci Semicond Process 2014;27:1028–35. [4] Mousavi-Kamazani M, Salavati-Niasari M, Sadeghinia M. Mater Lett 2015;142:145–9. [5] Straumal BB, Mazilkin AA, Protasova SG, Straumal PB, Myatieve AA, Schütz G, et al. Phys Met Metallogr 2012;113:1244–56. [6] Straumal BB, Protasovaa SG, Mazilkina AA, Tietze T, Goering E, Schütz G, et al. Beilstein J Nanotechnol 2013;4:361–9.
Acknowledgment Authors are grateful to council of University of Kashan for providing financial support to undertake this work.
Please cite this article as: Mousavi-Kamazani M, et al. Synthesis and characterization of CuInS2 quantum dot in the presence of novel precursors and its application in dyes solar cells. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2015.01.076i
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Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
Synthesis and characterization of CuInS2 quantum dot in the presence of novel precursors and its application in dyes solar cells Mehdi Mousavi-Kamazani, Masoud Salavati-Niasari n, S.Mostafa Hosseinpour-Mashkani, Mojgan Goudarzi Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P. O. Box. 87317-51167, Islamic Republic of Iran
art ic l e i nf o
a b s t r a c t
Article history: Received 23 December 2014 Accepted 19 January 2015
In this work, CuInS2 (CIS) quantum dot was successfully synthesized with the aid of carminic acid–Cu(II) as a novel copper precursor and thioglycolic acid (TGA( as a capping agent, sulfide source, and reducing agent in order to reduce Cu2 þ to Cu þ by a hydrothermal method. Carminic acid extracted from cochineal dye to synthesize copper precursor. Furthermore, in order to investigate the effect of different dyes and CIS-QDs on the solar cell yield, several experiments were performed. & 2015 Published by Elsevier B.V.
Keywords: CuInS2 Nanoparticles Solar energy materials Electron microscopy Natural dye
1. Introduction
2. Experimental
CuInS2 a critical semiconductor with a direct band gap of 1.5 eV is considered to be an efficient light absorbing semiconductor material for application in photovoltaic solar cells [1]. It is also known that the quantum dot CuInS2 can form a barrier layer on the nanocrystal TiO2 film, which can improve solar cells efficiency [2]. Over the past decades, considerable effort has been focused on synthesizing of CuInS2 through a solvothermal, solution–chemical method, and so on [1]. To the best of authors' knowledge, little is known about the synthesis of CuInS2 nanostructures by the hydrothermal method because it is hard to find a suitable reducing agent to reduce Cu2 þ to Cu þ in water. We suggest carminic acid–Cu(II) as a novel copper precursor to synthesize CuInS2 quantum dot through the hydrothermal technique based on utilizing TGA as a capping agent, sulfide source, and suitable reducing agent for reducing Cu2 þ to Cu þ . Furthermore, copper precursor was synthesized by extracting carminic acid from cochineal dye. The principal component of cochineal dye is carminic acid. Numerous natural dyes were applied as potential candidates in DSSC since ruthenium dyes, like N719, are very expensive and environmentally toxic. Therefore, we used Cu2 þ in order to synthesize the carminic acid–Cu(II) complex from the cochineal dye. Finally, the energy conversion efficiencies were investigated through several photovoltaic tests.
Materials and characterization: All the chemical reagents were of analytical grade and were used as received without any further purification. The FTO-TiO2 and FTO-TiO2/CIS/Pt-FTO structures were prepared as mentioned in the literature [3]. Cochineal dye was obtained from the dried bodies of female scale insects species, Dactylopius coccus, which feed on wild cacti. The XRD patterns were collected from a diffractometer of Philips Company with X’pert promonochromatized Cu Kα radiation (λ¼ 1.54 Å). A LEO 1455VP scanning electron microscope (SEM) was used to investigate the morphology of the products. TEM image was taken on an EM208S Philips transmission electron microscope with an accelerating voltage of 100 kV. Fourier transform infrared (FT-IR) spectra were recorded on Magna-IR, spectrometer 550 Nicolet with 0.125 cm 1 resolution in KBr pellets in the range of 400–4000 cm 1. Photocurrent density–voltage (J–V) curve was measured by using computerized digital multimeters (Ivium-nStat Multichannel potentiostat) and a variable load. A 300 W metal xenon lamp (Luzchem) served as a simulated sun light source, and its light intensity (or radiant power) was adjusted to simulated AM 1.5 radiation at 100 mW/cm2 with a filters for this purpose. Preparation of the carminic acid–Cu(II) complex: At first, 0.2 g of CuSO4 5H2O was dissolved in 20 ml of distilled water. Then, 1 g of cochineal dye was dissolved in 20 ml of distilled water and filtered through a smooth paper and gradually added into the above solution under magnetic stirring. The mixture was stirred and heated at 60 1C for 2 h. After thermal treatment, the system was maintained to cool down to room temperature, and the resulting precipitates were collected. Finally, it was washed with absolute ethanol and distilled
n
Corresponding author. Tel.: þ 98 31 55912383; fax: þ 98 31 5555 29 30. E-mail address: [email protected] (M. Salavati-Niasari).
http://dx.doi.org/10.1016/j.matlet.2015.01.076 0167-577X/& 2015 Published by Elsevier B.V.
Please cite this article as: Mousavi-Kamazani M, et al. Synthesis and characterization of CuInS2 quantum dot in the presence of novel precursors and its application in dyes solar cells. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2015.01.076i
67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101
M. Mousavi-Kamazani et al. / Materials Letters ∎ (∎∎∎∎) ∎∎∎–∎∎∎
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Fig. 1. Schematic diagram formation of (a) carminic acid–Cu(II) complex, (b) successive adsorption CIS-QD along with dye on the FTO-TiO2, (c) FT-IR spectra of carminic acid–Cu(II) complex and (d) CIS-QD.
water and was dried in vacuum at 80 1C for 10 h (Fig. 1a). CIS-QD was synthesized according to the following procedure: 1 mmol of carminic acid–Cu(II) and 1 mmol of InCl3 were dissolved in 40 mL of distilled water and stirred for about 10 min. Then, 10 mL of TGA was added drop wise into the above solution under magnetic stirring. Finally, the solution was sealed into 150 ml Teflon-lined stainless steel autoclave and heated at 140 (sample 1), 170 (sample 2), and 200 1C (sample 3) for 10 h. In order to investigate the effect of the TGA concentration, an experiment was performed in presence of 20 ml TGA (sample 4). Fabrication of FTO-TiO2/CIS-QD/cochineal dye/Pt-FTO: The autoclave, containing CIS precipitate, was cooled to room temperature naturally and the obtained precipitate was stirred hardly for 5 min. Afterwards, as prepared FTO-TiO2 structure [3] was put into the above precipitate for 10 h. Therefore, as-produced CIS-QD along with the dye subsidence on the FTO-TiO2 were made and washed with distilled water (Fig. 1b). Counter-electrode was made from deposition of a Pt solution on FTO glass. Afterwards, this electrode was placed over FTO-TiO2/CIS/dye electrode. Sealing was accomplished by pressing the two electrodes together on a double hot-plate at 110 1C. The redox electrolyte consisting of 0.05 M of LiI, 0.05 M of I2, and 0.5 M of 4-tert-butylpyridine in acetonitrile as a solvent was introduced into the cell through one of the two small holes drilled in the counter-electrode. Finally, these two holes were sealed by a small square of sealing sheet and characterized by a J–V test.
3. Results and discussion The FT-IR spectra of the carminic acid–Cu(II) precursor and the CIS quantum dot obtained at 200 1C in presence of 10 ml TGA (sample 3) are shown in Fig. 1c and d, respectively. The absorption
bands at 3434 and 1622 cm 1 could be attributed to the & (OH) stretching and bending vibrations, respectively. Moreover, the absorption peak at 503 cm 1 is due to Cu–O bond [4]. Furthermore, the absorption peak at 1334 cm 1 corresponds to –COOH symmetry stretching vibrations, while absorptions at 2925 and 824 cm–1 are related to stretching and bending vibrations of C–H bond, respectively. Fig. 1d shows the FT-IR spectrum of the CIS-QD (sample 3). Since the curve under this condition has no absorption peaks, pure CIS-QD was synthesized without any organic impurities. Fig. 2a–e illustrates the SEM and TEM images of the CIS 1–4 samples, respectively. Fig. 2a suggests that the product is mainly composed of a large amount of agglomerated nanoparticles. By increasing the reaction temperature to 170 1C (sample 2), the product consists of nanoparticles and nanosheets, as shown in Fig. 2b. By further increasing the reaction temperature to 200 1C while keeping the reaction time constant at 10 h (sample 3), the product is composed of small nanoparticles, as shown in Fig. 2c. Based on Fig. 2d, the morphology of the CIS in presence of 20 ml TGA (sample 4), product is composed of agglomerated nanoparticles. According to the TEM image of the CIS (sample 3, Fig. 2e), the particle size of the product is between 8 and 12 nm. Comparison of XRD patterns of 1–4 samples are shown in Fig. 3a–d, respectively. The XRD patterns of CIS (sample 1 and 2 at 140 and 170 1C, Fig. 3a and b) indicate the formation of CIS along with Cu2S, CuS, In2S3, S, and In2O3. By increasing the reaction temperature to 200 1C, pure tetragonal CuInS2 (space group I-42d, JCPDS no. 38-0777) with cell constants a ¼5.5200, b¼5.5200, and c¼ 11.1200 nm was obtained (sample 3, Fig. 3c). The XRD pattern of the as-synthesized product in presence of 20 ml TGA is shown in Fig. 3d, which indicates the product is composed of CIS, Cu2S, and CuS phases. In order to compare the effect of the adsorption mode on TiO2 surface on the
Please cite this article as: Mousavi-Kamazani M, et al. Synthesis and characterization of CuInS2 quantum dot in the presence of novel precursors and its application in dyes solar cells. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2015.01.076i
67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132
M. Mousavi-Kamazani et al. / Materials Letters ∎ (∎∎∎∎) ∎∎∎–∎∎∎
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3
Fig. 2. SEM images of (a) sample 1, (b) sample 2, (c) sample 3, (d) sample 4 and (e) TEM image of sample 3.
harvesting of light over a wide range of wavelengths, several tests were performed. The photovoltaic parameters obtained by measuring J–V curves (Fig. 3e and f) are shown in Table 1. The energy conversion efficiencies of the single-dye-sensitized solar cells using N719, CIS-QD, cochineal, and CIS-cochineal were 3.03, 0.12, 0.47, and 0.78%, respectively. Obviously a remarkable enhancement in efficiency takes place for the mixture of dye-nanoparticles compared to the pure dye or nanoparticles. This enhancement is the result of barrier layer formation by nanoparticles which in turn increases electron lifetime [2]. Furthermore, according to the Fig. 2, the obtained CuInS2 layers on TiO2 are nanograined and contain, therefore, both developed a very crystal/crystal interfaces as well as free surfaces with extremely high specific area which could be another reason for increasing solar cell yield in the presence of CuInS2 layers on TiO2. It has been recently demonstrated that the physical properties of pure and doped nanograined materials are strongly dependent on the presence of defects like interphase boundaries and grain boundaries on the presence of doping atoms in the (invisible for XRD) amorphous surficial, interfacial and intergranular layers [5,6]. The related reaction to form stoichiometric CuInS2 during hydrothermal process might be given in Eq. (5). Cu2 þ þ 2HSCH2COOH-Cu(HS)2 þ2CH2COOH þ
(1)
2Cu(HS)2-Cu2Sþ …
(2)
In3 þ þ3HSCH2COOH-In(HS)3 þ3CH2COOH þ
(3)
In(HS)3-In2S3 þ…
(4)
Cu2Sþ In2S3-2CuInS2
(5)
In comparison with similar works, the current work is easier to control and more affordable. In this study, thioglycolic acid was used instead of polyol solvents as a reducing agent to reduce of Cu2 þ to Cu þ and this product (CuInS2) can be easily synthesized in aqueous media. Besides, carminic acid was extracted from cochineal dye by Cu2 þ and new copper precursor was obtained and its using has many advantages such as: no need to any surfactant, possibility of single step production of three layered solar cells, presentation of a comprehensive method to increase of longevity of natural dyes etc.
4. Conclusions CuInS2 quantum dots were successfully synthesized through the hydrothermal method of carminic acid–Cu(II) complex and TGA as new precursors. The XRD results indicated that pure tetragonal CIS could only be obtained in the reaction temperature of 200 1C for 10 h. Furthermore, a single and double layer of the different dyes as sensitizers were successfully adjusted on TiO2 surface nanoparticles. The energy conversion efficiency of QD-dye adsorption is high (CIS-cochineal, 0.78) because the formation of CIS barrier layer is more than single-dye adsorption (cochineal, 0.47) on the TiO2 electrode.
Please cite this article as: Mousavi-Kamazani M, et al. Synthesis and characterization of CuInS2 quantum dot in the presence of novel precursors and its application in dyes solar cells. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2015.01.076i
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M. Mousavi-Kamazani et al. / Materials Letters ∎ (∎∎∎∎) ∎∎∎–∎∎∎
Fig. 3. XRD patterns of (a) sample 1, (b) sample 2, (c) sample 3, (d) sample 4 and photocurrent–voltage curves of DSSCs adsorbed with (e) N719, and (f) CIS, cochineal and CIS-cochineal.
Please cite this article as: Mousavi-Kamazani M, et al. Synthesis and characterization of CuInS2 quantum dot in the presence of novel precursors and its application in dyes solar cells. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2015.01.076i
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M. Mousavi-Kamazani et al. / Materials Letters ∎ (∎∎∎∎) ∎∎∎–∎∎∎
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Table 1 Energy conversion efficiency of DSSCs adsorbed with a: N719, b: CIS, cochineal and CIS-cochineal dye. Dyes
Voc (V)
Jsc (mA/cm2)
FF
η (%)
N719 CIS-QD Cochineal CIS-Cochineal
0.75 0.52 0.64 0.62
9.7 0.494 1.21 1.94
0.42 0.47 0.61 0.65
3.03 0.12 0.47 0.78
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References [1] Zhou J, Li S, Gong X, Yang Y, Guo Y. Mater Lett 2011;65:2001–3. [2] Guo F, He J, Li J, Wu W, Hang Y, Jianli. H. J Colloid Interface Sci 2013;408:59–65. [3] Panahi-Kalamuei M, Mohandes F, Mousavi-Kamazani M, Salavati-Niasari M, Fereshteh Z, Fathi M. Mater Sci Semicond Process 2014;27:1028–35. [4] Mousavi-Kamazani M, Salavati-Niasari M, Sadeghinia M. Mater Lett 2015;142:145–9. [5] Straumal BB, Mazilkin AA, Protasova SG, Straumal PB, Myatieve AA, Schütz G, et al. Phys Met Metallogr 2012;113:1244–56. [6] Straumal BB, Protasovaa SG, Mazilkina AA, Tietze T, Goering E, Schütz G, et al. Beilstein J Nanotechnol 2013;4:361–9.
Acknowledgment Authors are grateful to council of University of Kashan for providing financial support to undertake this work.
Please cite this article as: Mousavi-Kamazani M, et al. Synthesis and characterization of CuInS2 quantum dot in the presence of novel precursors and its application in dyes solar cells. Mater Lett (2015), http://dx.doi.org/10.1016/j.matlet.2015.01.076i
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