In this paper, we present the results of the calculations of optical losses in the solar cells layers based
on heterojunction n-ZnMgO / p-CuO with ZnO and ITO frontal contacts. The calculations were carried out
taking into account a light absorption in the auxiliary layers of the device. As a result, the spectral dependencies
of transmittance Т(λ) in the absorber layer of solar cell were defined. It is made possible to optimize
the design of the solar cells based on such heterojunctions

Diachenko, Oleksii Viktorovych

Kheraj, V.A.

Kurbatov, Denys Ihorovych

Opanasiuk, Anatolii Serhiiovych

Panchal, C.J.

Patel, P.B.

Priya, Suryavanshi

Д`яченко, Олексій Вікторович

Дьяченко, Алексей Викторович

Курбатов, Денис Игоревич

Курбатов, Денис Ігорович

Опанасюк, Анатолий Сергеевич

Опанасюк, Анатолій Сергійович

Electronic Sumy State University Institutional Repository

JOURNAL OF NANO- AND ELECTRONIC PHYSICS ЖУРНАЛ НАНО- ТА ЕЛЕКТРОННОЇ ФІЗИКИ Vol. 9 No 4, 04002(4pp) (2017) Том 9 № 4, 04002(4cc) (2017)   2077-6772/2017/9(4)04002(4) 04002-1  2017 Sumy State University The Performance Optimization of Thin-Film Solar Converters Based on n-ZnMgO / p-CuO    Heterojunctions  O.V. Diachenko1, A.S. Opanasyuk1,*, D.I. Kurbatov1, P.B. Patel2, C.J. Panchal3,†,  Priya Suryavanshi3, V.A. Kheraj4  1 Sumy State University, 2, Rymsky Korsakov Str., 40007 Sumy, Ukraine 2 Sardar Patel University, Vallabh Vidyanagar, 388120 Gujarat, India 3 The M.S. University of Baroda Vadodara, 390001, India 4 S. V. National Institute of Technology, 395007 Surat, India  (Received 15 April 2017; revised manuscript received 25 July 2017; published online 27 July 2017)  In this paper, we present the results of the calculations of optical losses in the solar cells layers based on heterojunction n-ZnMgO / p-CuO with ZnO and ITO frontal contacts. The calculations were carried out taking into account a light absorption in the auxiliary layers of the device. As a result, the spectral de-pendencies of transmittance Т() in the absorber layer of solar cell were defined. It is made possible to op-timize the design of the solar cells based on such heterojunctions.  Keywords: Zinc magnesium oxide, Copper oxide, Optical losses, Recombination losses, Efficiency, Thick-ness, Heterojunction.  DOI: 10.21272/jnep.9(4).04002 PACS numbers: 88.40.hj, 42.25.Bs                                                             * opanasyuk_sumdu@ukr.net † cjpanchal_msu@yahoo.com 1. INTRODUCTION  Solar power is one of the most promising areas of renewable energy. Today, solar cells based on silicon dominate in photovoltaics. However, the need to reduce the cost of obtaining solar energy leads to the necessity of finding the new materials for photovoltaic cells. Copper oxides such as CuO and Cu2O are promising photovoltaic materials. They are p-type semiconductors and have band gap ~1.3 eV (CuO) and ~2.3 eV (Cu2O), respectively [1-6]. Because of Cu is abundant in nature, cheap and nontoxic, the first oxide could be used as an absorbing layer, and the second as a window layer of thin-film solar cells for large-scale solar energy conversion [3, 7, 8]. Theoretical studies indicate that the maximum efficiency of thin-film solar cells based on CuO absorbing layer is (32-34) % while using Cu2O the solar cells can be obtained with an efficiency exceeding 20 % [9].  The modern thin-film solar cell is usually construct-ed using heterojunctions [1, 2, 5, 6]. Generally, a trans-parent conductive layer (ITO), are used as the conduc-tive and the window layer of such devices, although in recent years solar cells with a layer of aluminum-doped zinc oxide (ZnO: Al) become increasingly popular [10, 11]. However, a number of studies [12], [13] have found that n-ZnO / p-CuO heterojunctions have good rectify-ing properties despite the fact that the contacting ma-terials have a different crystal structure. This is due to the good agreement of lattice parameters of materials for facets formed by vectors b and c [12]. Unfortunately, the efficiency of solar cells based on n-ZnO / p-CuO heterojunction in our time does not exceed 2.88 % [14]. Increasing the efficiency of real solar cells is possible by minimizing energy loss due to optimization of their design and to improve the properties of layers. One way to improve the performance of solar cells is the adding impurities of isovalent Mg in zinc oxide. This allows controllably change a band gap, lattice parameters and work function of a material and thus optimize heterojunction characteristics. This led to the goal and objectives of the study. The main purpose of this work is to calculate the optical losses in solar cells based on n-ZnMgO / p-CuO heterojunction with frontal ZnO and ITO contacts to optimize their designs.  2. RESULTS AND DISCUSSION  2.1 The Losses of Light Reflection from Layers in Solar Cell  Usually, thin film solar cell consist of a window and absorbing layers, front and back contacts. In this paper, we discuss the thin film solar cells on the basis of hetero-junctions which have the «superstrate» type. Their design is schematically shown in Fig 1.    Fig. 1 – The schematic design of solar cell based on  n-ZnMgO / p-CuO heterojunction  The thickness of the ZnMgO window layer was cho-sen in the range of d  30 nm up to 400 nm to modeling the process of reflection and absorption of the light in auxiliary layers of photovoltaic devices. The thickness of the ZnO (ITO) layers was taken as d  100 and 200 nm. These values of thicknesses have layers of the real solar cells [11]. The ZnMgO solid solution contain-ing 30 percent of magnesium. Recently, ZnMgO solid solution also being used for creating a solar cell con-taining a copper oxide layer, based on ZnMgO / CuO2  O.V. DIACHENKO, A.S. OPANASYUK, ET AL. J. NANO- ELECTRON. PHYS. 9, 04002 (2017)   04002-2 heterojunction [15]. The sunlight flows before getting into the absorbing layer CuO, where the photogeneration of electron-hole pairs occurs under his influence, passes through a number of auxiliary layers of solar cell: glass, ITO (ZnO) and ZnMgO. With this occurs a reflection of the radiation from boundaries of different materials (air-glass, glass-ITO (ZnO), ITO (ZnO)-ZnMgO and ZnMgO-CuO) and absorption of light in the window and buffer layers of the solar converter and in the glass. These losses lead to reduced effectiveness of solar converter. We have used Fresnel equation for calculating the reflection coefficient at the interface between two con-tacting materials [16, 17]:   21 21 2n nRn n    , (1)  where n1 and n2 – refractive indexes of the contacting materials. For the electrically conductive materials, reflection coefficient was determined using the following expres-sion [17]:   * * 2 21 2 1 2 1 22 2* *1 2 1 21 2( ) ( )( ) ( )n n n n k kRn n k kn n      , (2)  where n1*, n2* – complex refractive index; k1, k2 – is the extinction coefficient. To obtain the spectral dependences of n and k were used refractive index and extinction coefficient of ITO, ZnO, ZnMgO and CuO given in [18]. The values of refractive index and extinction coefficient for air were taken n1  1, and k1  0, respectively. Fig. 2a shows the calculated spectral dependencies of reflection coefficient from layers of a solar cell at their direct contact with air. As shown in the figure, the lowest reflection coefficient on the interface air - glass, and the largest observed at the interface air - CuO. The calculated spectral dependencies of reflection coef-ficient from the interfaces between layers, that located one after another in a solar cell are presented in Fig. 2b. As expected, because of the low refractive index of light in the material we observe the lowest value of reflection coefficients at the interfaces ZnMgO-ZnO (R  1-2∙10 – 3) та ZnMgO-ITO (R  1-10∙10 – 3), and the biggest values at the interface ZnMgO-CuO (R  0.22-0.28). The value of R for interfaces air-ZnMgO and air-glass taking values (0.10-0.15) and (0.03-0.04), respectively. Apart from the absorption processes in solar cell lay-ers, the transmittance of the light in CuO absorbing layer can be defined by the formula T  1 – R. So transmittance of the photovoltaic converter with a multilayer structure can be found by the formula [16, 19]:   12 23 34 45( ) (1 )(1 )(1 )(1 )T R R R R      , (3)  where R12, R23, R34, R45 – reflection from the following interfaces: air-glass, glass-ZnO(ITO), ZnO(ITO)-ZnMgO, ZnMgO-CuO.    Fig. 2 – The spectral dependences of the reflection coefficient (R) for interfaces: air-glass (1), air-ZnMgO (2), air-ZnO (3) air-ITO (4) air-CuO (5) (a) and ZnMgO-CuO (1) glass-ZnO (2) glass-ITO (3), ITO-ZnMgO (4), ZnO-ZnMgO (5) (b)  It should be noted that this equation does not ac-count for multiple reflections in the glass plate, ZnO (ITO) and CuO layers, which is quite acceptable because of the small difference of reflection coefficients at the interfaces (Fig. 2b). It also allows us to ignore interference effects.    Fig. 3 – Spectral dependence transmittance T() and reflec-tance R() of a solar cell with ITO / ZnMgO / CuO (1) and ZnO / ZnMgO / CuO (2) structures. The reflection of light from the interphase interfaces was taking into account  Fig. 3 shows the dependence of the transmission T and reflection R of the wavelength  considered for the solar converter. Solar cells based on n-ZnMgO / p-CuO heterojunction as with the ZnO as well as with ITO layer have very high-value of light transmission coeffi- THE PERFORMANCE OPTIMIZATION OF THIN-FILM SOLAR CONVERTERS … J. NANO- ELECTRON. PHYS. 9, 04002 (2017)   04002-3 cient ( 90 %), which affects their efficiency of convert-ing solar energy into electricity. As shown in Fig. 4, the transmittance of ZnO layer is very close to the values obtained for the device containing ITO. To determine the optimal material of conductive layer solar cell was calculated a so-called coefficient of optical power loss of the device. It was determined by the formula:   max1max1( ) ( )( )niiT TnT , (4)  Knowing that Tmax()  1, then expression (4) is simplified to the form:   111 ( )niiη T λn    , (5)  The results of calculation of the coefficient of optical power loss in the solar cells with various structure are presented in Table 1.  Table 1 – Coefficients of optical power loss in the solar cells  Structure of solar cell Optical power loss coefficient, % The coefficient of light passing, % ITO/ZnMgO/CuO 8.45 91.55 ZnO/ZnMgO/CuO 9.52 90.48  As the table shows, the optical loss in the structures ITO / ZnMgO / CuO and ZnO / ZnMgO / CuO differ by only 1.07 %. But the best value of passage of light to the absorber layer has a structure with ITO (91.55 %).  2.2 The Losses of Light Absorption in Solar Cell Layers  In addition to losses on light reflection from layers should take into account the optical losses on light absorp-tion in the auxiliary layers for solar converters. The transmittance coefficient of a multilayer structure in view of losses of reflection and absorption at all layers of the solar cell can be calculated using the expression [20]:  1 1 2 212 23 34 45( ) (1 )(1 )(1 )(1 )( )( )d dT R R R R e e         (6)  where 1, 2 – are absorption coefficients of the materi-als of the window and the conductive layer; d1, d2 – the thicknesses of these layers. The absorption coefficient of solar radiation () in view it's extinction coefficient as a function of wave-length k() is calculated by the following equation:   4( ) k  . (7)  Fig. 4 shows the dependence of T on the wavelength  for solar cell based on n-ZnO / p-CuO heterojunction including losses on light absorption in the auxiliary layers with different thickness values. Analysis of the dependencies indicates that changing the thickness of 30 to 400 nm of ZnMgO layer somewhat reduces the value of transmittance solar converter. It is established that an increase the thickness of the layer from d  30 nm to d  400 nm the optical losses increase for the device with a layer of ITO by 2.16 % при dITO  100 nm and 0.92 % at dITO  200 nm. For the solar cell with a layer of ZnO, the loss value increased to 2.14 % at dZnO  100 nm and to 0.9 % at dZnO  200 nm. At the same time transmittance values of the device with ITO     Fig. 4 – Spectral transmittance coefficients of multilayer struc-tures glass / ITO / ZnMgO / CuO and glass / ZnO / ZnMgO / CuO at ZnMgO thickness: 30-400 nm and ITO (ZnO): 100 nm (a) and 200 nm (b)    Fig. 5 – Dependence of losses of light for structures glass / ITO / ZnMgO / CuO (solid lines) and glass / ZnO / ZnMgO / CuO (dotted lines) at thickness of ITO (ZnO): 100 nm (a) and 200 nm (b)  layer is somewhat greater than the corresponding val-ue for the structure with ZnO layer. Thus, calculations show that a layer of ITO is more attractive compared with ZnO for use in solar cells because improves the volume of a passage of light to the CuO absorber layer.  O.V. DIACHENKO, A.S. OPANASYUK, ET AL. J. NANO- ELECTRON. PHYS. 9, 04002 (2017)   04002-4 3. CONCLUSIONS  In the paper, the optical losses were defined in thin film solar converters based on n-ZnMgO / p-CuO hetero-junction with frontal contacts ZnO and ITO. Such solar cells have a very high value of light transmittance ( 90 %) as in the case of the conductive layer of ZnO as well as ITO. It is established that the value of transmittance device with a layer of ITO by 1.07 % higher than the correspond-ing values obtained for the structure with ZnO layer. The summary (optical and recombination) losses of the solar converter with different structures at dZnMgO  30 nm is equaled 14.26 % and 18.70 % for ZnO and ITO respectively. On the basis of calculations, it is possible to optimize the structure of photovoltaic converter minimizing these losses.  AKNOWLEDGEMENTS  This research was supported by the Ministry of Edu-cation and Science of Ukraine (Grant No. 0116U002619, No. 0115U000665c, No. 0116U006813).   REFERENCES  1. H. Kidowaki, T. Oku, T. Akiyama, Int. J. Res. Rev. Appl. Sci. 13, 67 (2012). 2. V. Kumar, S. Masudi-Panah, C. C. Tan, T. K. S. Wong, D. Z. Chi, and G. K. Dalapati, 2013 IEEE 5th Internation-al Nanoelectronics Conference (INEC), 443 (Singapore: 2013). 3. R. Wick, S.D. Tilley, J. Phys. Chem. C 119, 26243 (2015). 4. Y. Nishi, T. Miyata, J. Nomoto, T. Minami, 2011 37th IEEE Photovoltaic Specialists Conference, 266 (Washing-ton: 2011). 5. Y. Ievskaya, R.L.Z. Hoye, A. Sadhanala, K.P. Musselman, J.L. MacManus-Driscoll, Sol. Energy Mater. Sol. C. 135, 43 (2015). 6. A. Bhaumik, A. Haque, P. Karnati, M.F.N. Taufique, R. Patel, K. Ghosh, Thin Solid Films 572, 126 (2014). 7. S.S. Wilson, J.P. Bosco, Y. Tolstova, D.O. Scanlon, G.W. Watson, H.A. Atwater, J. Chem. Inf. Model. 53, 1689 (2013). 8. Y.-F. Lim, C.S. Chua, C.J.J. Lee, D. Chi, Phys. Chem. Chem. Phys. 16, 25928 (2014). 9. T. Oku, R. Motoyoshi, K. Fujimoto, T. Akiyama, B. Jeyadevan, J. Cuya, J. Phys. Chem. Solids 72, 1206 (2011). 10. A. Rios-Flores, O. Arés, J. Camacho, V. Rejon, J. Peña, Sol. Energy 86, 780 (2012). 11. R. Scheer, H.W. Schock, Chalcogenide Photovoltaics: Physics, Technologies, and Thin Film Devices (Weinheim: Wiley-VCH: 2011). 12. O.L. Lisitski, M.E. Kumekov, S.E. Kumekov, E.I. Terukov, Semiconductors 43, 765 (2009). 13. S.R. Adilov, M.E. Kumekov, S.E. Kumekov, E.I. Terukov, Semiconductors 47, 655 (2013). 14. T. Wong, S. Zhuk, S. Masudy-Panah, G. Dalapati, Materials 9, 271 (2016). 15. H. Tampo, H. Shibata, K. Maejima, T.-W. Chiu, H. Itoh, A. Yamada, K. Matsubara, P. Fons, Y. Chiba, T. Wakamatsu, Y. Takeshita, H. Kanie, S. Niki, Appl. Phys. Lett. 94, 242107 (2009). 16. O.A. Dobrozhan, A.S. Opanasyuk, V.V. Grynenko, J. Nano- Electron. Phys. 6, 04035 (2014). 17. S.O. Kasap, Optoelectronics and Photonics: Principles and Practices (New Jersey: Prentice-Hall: 2001). 18. Handbook of Physical Properties of Semiconductors (Ed. S. Adachi) (Boston: Kluwer Academic Publishers: 2004). 19. T. Mykytyuk, V. Roshko, L. Kosyachenko, Acta Phys. Pol. 122, 1073 (2012).  

The Performance Optimization of Thin-Film Solar Converters Based on n-ZnMgO / p-CuO Heterojunctions

In this paper, we present the results of the calculations of optical losses in the solar cells layers based on heterojunction n-ZnMgO / p-CuO with ZnO and ITO frontal contacts. The calculations were carried out taking into account a light absorption in the auxiliary layers of the device. As a result, the spectral dependencies of transmittance Т() in the absorber layer of solar cell were defined. It is made possible to optimize the design of the solar cells based on such heterojunctions

4TH INTERNATIONAL SYMPOSIUM ON SEMICONDUCTOR MATERIALS AND DEVICES (ISSMD-4) 8th -10th March, 2017  School of Materials Sciences and Nanotechnology, Jadavpur University, Kolkata - 700 032, India 84   Fig. 1: Evolution of Ld and  product with flow variation Fig. 2: DOS data of Ar93 and Ar95 in AD and LS state  Fig. 3: Evolution of conversion efficiency and fill factor with time for the solar cells fabricated with (a) Ar93 and (b) Ar95  References: 1. C. Knights, R.A. Lujan, M.P. Rosenblum, R.A. Street, D.K. Beiglese., Appl Phys Lett. 38 (1981) 131. 2. C. Longeaud and J. P. Kleider, Phys. Rev. B 45 (1992) 11672.   The performance optimization of thin-film solar converters based on n-ZnMgO / p-CuO heterojunctions  O.V. Diachenko1, A.S. Opanasyuk1, D.I. Kurbatov1, Patel P.B.2, Panchal C. J.3, Priya Suryavanshi3, Kheraj V.A.4  1Dept. of Electronics and Computer Technology, Sumy State University, Sumy, Ukraine Email: alexey.dyachenko@ukr.net, opanasyuk_sumdu@ukr.net 2Department of Electronics, Sardar Patel University, Vallabh Vidyanagar-388120, Gujarat, India 3Applied Physics Department, The M.S. University of Baroda, Vadodara-390001, India Email: cjpanchal_msu@yahoo.com 4Department of Applied Physics, S. V. National Institute of Technology, Surat 395007, India  In this paper, we present the results of the calculations of optical losses in the solar cells layers based on heterojunction n-ZnMgO / p-CuO with ZnO and ITO frontal contacts. The calculations were carried out taking into account a light absorption in the auxiliary layers 152 4TH INTERNATIONAL SYMPOSIUM ON SEMICONDUCTOR MATERIALS AND DEVICES (ISSMD-4) 8th -10th March, 2017  School of Materials Sciences and Nanotechnology, Jadavpur University, Kolkata - 700 032, India 85  of the device. As a result, the spectral dependencies of transmittance Т() in the absorber layer of solar cell were defined. It is made possible to optimize the design of the solar cells based on such heterojunctions.   Diamond-like Nanocomposite Thin Film as a Promising Anti-Reflecting Coating for Silicon Based Solar Cell  Sukhendu Jana1,3*, Sayan Das1,2, Debasish De1, Anup Mondal2,3 and Utpal Gangopadhyay1  1Advanced Research in Renewable Energy and Sensor System Laboratory, Meghnad Saha Institute of Technology, Techno India Group, Kolkata-150, India 2Dept. of Chemistry, Bengal Engineering and Sciences University, Shibpur-103, Howrah, India 3Centre of Excellence for Green Energy and Sensor System, Bengal Engineering and Sciences University, Shibpur-103, Howrah, India *Email: sukhendu123@gmail.com Tel. +919433130733, Fax. +91-03324431754   In the present study, the anti-reflection property of diamond-like nanocomposite (DLN) thin film on silicon based solar cell has been investigated. The film has been deposited by plasma assisted chemical vapor deposition (PACVD) method and characterized by FTIR, Raman spectroscopy and FESEM. The performance of the DLN thin film as antireflection coating (ARC) on c-textured silicon has been analyzed by measuring the average reflection in the spectral range of 300 to 1100 nm. The result shows that, the average reflection from texture silicon reduces from 13.55 % to 4.58 %, which is significantly lower than conventional SiNx ARC. Moreover, the average EQE of the solar cell increases by 18% after coating with DLN thin film. The film thickness and refractive index were 86 nm and 1.89 respectively. The optical band gap of the film has been estimated using Tauc relation and it was 3.18 eV. The DLN thin film has a great potential to use as anti-reflection coating for silicon based solar cell.   CBD Zinc Sulfide Film Using Non-Toxic Complexing Agent as Low Cost Antireflection Coating On Multi-Crystalline Silicon Solar Cell  Kaustuv Dasgupta1,2*, Soma Ray1,2,  Baishakhi Pal1,3, Subhadeep Nandy1,  Sayan Das1,2, Sukhendu Jana1,2 , Anup Mondal2 and Utpal Gangopadhyay2  1Advanced Research in Renewable Energy and Sensor System Lab, Meghnad Saha Institute of Technology, Nazirabad,Uchhepota, Kolkata-700 150, West Bengal, India 2Centre of Excellence of Green Energy and Sensor System, Shibpur, Howrah – 711 103, West Bengal, India 3Department of Physics, Jadavpur University, Kolkata – 700 032, West Bengal, India *Email: kaustuvdasgupta83@gmail.com   In the present study, the anti-reflection property of diamond-like nanocomposite (DLN) thin film on silicon based solar cell has been investigated. The film has been deposited by plasma assisted chemical vapor deposition (PACVD) method and characterized by FTIR, Raman spectroscopy and FESEM. The performance of the DLN thin film as antireflection 184 179 

The performance optimization of thin-film solar converters based on n-ZnMgO / p-CuO heterojunctions

SocioEconomic Challenges Journal (Sumy State University)

4TH INTERNATIONAL SYMPOSIUM ON SEMICONDUCTOR MATERIALS AND DEVICES (ISSMD-4) 8th -10th March, 2017 
 
School of Materials Sciences and Nanotechnology, Jadavpur University, Kolkata - 700 032, India 84 
 
 
Fig. 1: Evolution of L
d
 and  product with flow variation Fig. 2: DOS data of Ar93 and Ar95 in AD and 
LS state 
 
Fig. 3: Evolution of conversion efficiency and fill factor with time for the solar cells fabricated with (a) 
Ar93 and (b) Ar95 
 
References: 
1. C. Knights, R.A. Lujan, M.P. Rosenblum, R.A. Street, D.K. Beiglese., Appl Phys Lett. 38 (1981) 
131. 
2. C. Longeaud and J. P. Kleider, Phys. Rev. B 45 (1992) 11672. 
 
 
The performance optimization of thin-film solar converters based on n-ZnMgO / p-
CuO heterojunctions 
 
O.V. Diachenko
1
, A.S. Opanasyuk
1
, D.I. Kurbatov
1
, Patel P.B.
2
, Panchal C. J.
3
, Priya 
Suryavanshi
3
, Kheraj V.A.
4
 
 
1
Dept. of Electronics and Computer Technology, Sumy State University, Sumy, Ukraine 
Email: alexey.dyachenko@ukr.net, opanasyuk_sumdu@ukr.net 
2
Department of Electronics, Sardar Patel University, Vallabh Vidyanagar-388120, Gujarat, 
India 
3
Applied Physics Department, The M.S. University of Baroda, Vadodara-390001, India 
Email: cjpanchal_msu@yahoo.com 
4
Department of Applied Physics, S. V. National Institute of Technology, Surat 395007, India 
 
In this paper, we present the results of the calculations of optical losses in the solar cells 
layers based on heterojunction n-ZnMgO / p-CuO with ZnO and ITO frontal contacts. The 
calculations were carried out taking into account a light absorption in the auxiliary layers 
152 
4TH INTERNATIONAL SYMPOSIUM ON SEMICONDUCTOR MATERIALS AND DEVICES (ISSMD-4) 8th -10th March, 2017 
 
School of Materials Sciences and Nanotechnology, Jadavpur University, Kolkata - 700 032, India 85 
 
of the device. As a result, the spectral dependencies of transmittance Т() in the absorber 
layer of solar cell were defined. It is made possible to optimize the design of the solar cells 
based on such heterojunctions. 
 
 
Diamond-like Nanocomposite Thin Film as a Promising Anti-Reflecting Coating for 
Silicon Based Solar Cell 
 
Sukhendu Jana
1,3*
, Sayan Das
1,2
, Debasish De
1
, Anup Mondal
2,3
 and Utpal Gangopadhyay
1
 
 
1
Advanced Research in Renewable Energy and Sensor System Laboratory, Meghnad Saha 
Institute of Technology, Techno India Group, Kolkata-150, India 
2
Dept. of Chemistry, Bengal Engineering and Sciences University, Shibpur-103, Howrah, 
India 
3
Centre of Excellence for Green Energy and Sensor System, Bengal Engineering and 
Sciences University, Shibpur-103, Howrah, India 
*Email: sukhendu123@gmail.com Tel. +919433130733, Fax. +91-03324431754  
 
In the present study, the anti-reflection property of diamond-like nanocomposite (DLN) thin 
film on silicon based solar cell has been investigated. The film has been deposited by 
plasma assisted chemical vapor deposition (PACVD) method and characterized by FTIR, 
Raman spectroscopy and FESEM. The performance of the DLN thin film as antireflection 
coating (ARC) on c-textured silicon has been analyzed by measuring the average reflection 
in the spectral range of 300 to 1100 nm. The result shows that, the average reflection from 
texture silicon reduces from 13.55 % to 4.58 %, which is significantly lower than 
conventional SiNx ARC. Moreover, the average EQE of the solar cell increases by 18% after 
coating with DLN thin film. The film thickness and refractive index were 86 nm and 1.89 
respectively. The optical band gap of the film has been estimated using Tauc relation and it 
was 3.18 eV. The DLN thin film has a great potential to use as anti-reflection coating for 
silicon based solar cell. 
 
 
CBD Zinc Sulfide Film Using Non-Toxic Complexing Agent as Low Cost Antireflection 
Coating On Multi-Crystalline Silicon Solar Cell 
 
Kaustuv Dasgupta
1,2*
, Soma Ray
1,2
,  Baishakhi Pal
1,3
, Subhadeep Nandy
1
,  Sayan Das
1,2
, 
Sukhendu Jana
1,2
 , Anup Mondal
2
 and Utpal Gangopadhyay
2
 
 
1
Advanced Research in Renewable Energy and Sensor System Lab, Meghnad Saha Institute 
of Technology, Nazirabad,Uchhepota, Kolkata-700 150, West Bengal, India 
2
Centre of Excellence of Green Energy and Sensor System, Shibpur, Howrah – 711 103, 
West Bengal, India 
3
Department of Physics, Jadavpur University, Kolkata – 700 032, West Bengal, India 
*Email: kaustuvdasgupta83@gmail.com  
 
In the present study, the anti-reflection property of diamond-like nanocomposite (DLN) thin 
film on silicon based solar cell has been investigated. The film has been deposited by 
plasma assisted chemical vapor deposition (PACVD) method and characterized by FTIR, 
Raman spectroscopy and FESEM. The performance of the DLN thin film as antireflection 
184 
179 


English

JOURNAL OF NANO- AND ELECTRONIC PHYSICS ЖУРНАЛ НАНО- ТА ЕЛЕКТРОННОЇ ФІЗИКИ 
Vol. 9 No 4, 04002(4pp) (2017) Том 9 № 4, 04002(4cc) (2017) 
 
 
2077-6772/2017/9(4)04002(4) 04002-1  2017 Sumy State University 
The Performance Optimization of Thin-Film Solar Converters Based on n-ZnMgO / p-CuO    
Heterojunctions 
 
O.V. Diachenko1, A.S. Opanasyuk1,*, D.I. Kurbatov1, P.B. Patel2, C.J. Panchal3,†,  
Priya Suryavanshi3, V.A. Kheraj4 
 
1 Sumy State University, 2, Rymsky Korsakov Str., 40007 Sumy, Ukraine 
2 Sardar Patel University, Vallabh Vidyanagar, 388120 Gujarat, India 
3 The M.S. University of Baroda Vadodara, 390001, India 
4 S. V. National Institute of Technology, 395007 Surat, India 
 
(Received 15 April 2017; revised manuscript received 25 July 2017; published online 27 July 2017) 
 
In this paper, we present the results of the calculations of optical losses in the solar cells layers based 
on heterojunction n-ZnMgO / p-CuO with ZnO and ITO frontal contacts. The calculations were carried out 
taking into account a light absorption in the auxiliary layers of the device. As a result, the spectral de-
pendencies of transmittance Т() in the absorber layer of solar cell were defined. It is made possible to op-
timize the design of the solar cells based on such heterojunctions. 
 
Keywords: Zinc magnesium oxide, Copper oxide, Optical losses, Recombination losses, Efficiency, Thick-
ness, Heterojunction. 
 
DOI: 10.21272/jnep.9(4).04002 PACS numbers: 88.40.hj, 42.25.Bs 
 
 
                                                          
* opanasyuk_sumdu@ukr.net 
† cjpanchal_msu@yahoo.com 
1. INTRODUCTION 
 
Solar power is one of the most promising areas of 
renewable energy. Today, solar cells based on silicon 
dominate in photovoltaics. However, the need to reduce 
the cost of obtaining solar energy leads to the necessity 
of finding the new materials for photovoltaic cells. 
Copper oxides such as CuO and Cu2O are promising 
photovoltaic materials. They are p-type semiconductors 
and have band gap ~1.3 eV (CuO) and ~2.3 eV (Cu2O), 
respectively [1-6]. Because of Cu is abundant in nature, 
cheap and nontoxic, the first oxide could be used as an 
absorbing layer, and the second as a window layer of thin-
film solar cells for large-scale solar energy conversion [3, 
7, 8]. Theoretical studies indicate that the maximum 
efficiency of thin-film solar cells based on CuO absorbing 
layer is (32-34) % while using Cu2O the solar cells can be 
obtained with an efficiency exceeding 20 % [9].  
The modern thin-film solar cell is usually construct-
ed using heterojunctions [1, 2, 5, 6]. Generally, a trans-
parent conductive layer (ITO), are used as the conduc-
tive and the window layer of such devices, although in 
recent years solar cells with a layer of aluminum-doped 
zinc oxide (ZnO: Al) become increasingly popular [10, 
11]. However, a number of studies [12], [13] have found 
that n-ZnO / p-CuO heterojunctions have good rectify-
ing properties despite the fact that the contacting ma-
terials have a different crystal structure. This is due to 
the good agreement of lattice parameters of materials 
for facets formed by vectors b and c [12]. Unfortunately, 
the efficiency of solar cells based on n-ZnO / p-CuO 
heterojunction in our time does not exceed 2.88 % [14]. 
Increasing the efficiency of real solar cells is possible by 
minimizing energy loss due to optimization of their 
design and to improve the properties of layers. 
One way to improve the performance of solar cells is 
the adding impurities of isovalent Mg in zinc oxide. 
This allows controllably change a band gap, lattice 
parameters and work function of a material and thus 
optimize heterojunction characteristics. This led to the 
goal and objectives of the study. The main purpose of 
this work is to calculate the optical losses in solar cells 
based on n-ZnMgO / p-CuO heterojunction with frontal 
ZnO and ITO contacts to optimize their designs. 
 
2. RESULTS AND DISCUSSION 
 
2.1 The Losses of Light Reflection from Layers 
in Solar Cell 
 
Usually, thin film solar cell consist of a window and 
absorbing layers, front and back contacts. In this paper, 
we discuss the thin film solar cells on the basis of hetero-
junctions which have the «superstrate» type. Their design 
is schematically shown in Fig 1. 
 
 
 
Fig. 1 – The schematic design of solar cell based on  
n-ZnMgO / p-CuO heterojunction 
 
The thickness of the ZnMgO window layer was cho-
sen in the range of d  30 nm up to 400 nm to modeling 
the process of reflection and absorption of the light in 
auxiliary layers of photovoltaic devices. The thickness 
of the ZnO (ITO) layers was taken as d  100 and 
200 nm. These values of thicknesses have layers of the 
real solar cells [11]. The ZnMgO solid solution contain-
ing 30 percent of magnesium. Recently, ZnMgO solid 
solution also being used for creating a solar cell con-
taining a copper oxide layer, based on ZnMgO / CuO2 
 O.V. DIACHENKO, A.S. OPANASYUK, ET AL. J. NANO- ELECTRON. PHYS. 9, 04002 (2017) 
 
 
04002-2 
heterojunction [15]. 
The sunlight flows before getting into the absorbing 
layer CuO, where the photogeneration of electron-hole 
pairs occurs under his influence, passes through a 
number of auxiliary layers of solar cell: glass, ITO 
(ZnO) and ZnMgO. With this occurs a reflection of the 
radiation from boundaries of different materials (air-
glass, glass-ITO (ZnO), ITO (ZnO)-ZnMgO and ZnMgO-
CuO) and absorption of light in the window and buffer 
layers of the solar converter and in the glass. These 
losses lead to reduced effectiveness of solar converter. 
We have used Fresnel equation for calculating the 
reflection coefficient at the interface between two con-
tacting materials [16, 17]: 
 
 
2
1 2
1 2
n n
R
n n
 
  
 
, (1) 
 
where n1 and n2 – refractive indexes of the contacting 
materials. 
For the electrically conductive materials, reflection 
coefficient was determined using the following expres-
sion [17]: 
 
 
* * 2 2
1 2 1 2 1 2
2 2* *
1 2 1 21 2
( ) ( )
( ) ( )
n n n n k k
R
n n k kn n
   
 
  
, (2) 
 
where n1*, n2* – complex refractive index; k1, k2 – is the 
extinction coefficient. 
To obtain the spectral dependences of n and k were 
used refractive index and extinction coefficient of ITO, 
ZnO, ZnMgO and CuO given in [18]. The values of 
refractive index and extinction coefficient for air were 
taken n1  1, and k1  0, respectively. 
Fig. 2a shows the calculated spectral dependencies 
of reflection coefficient from layers of a solar cell at 
their direct contact with air. As shown in the figure, 
the lowest reflection coefficient on the interface air - 
glass, and the largest observed at the interface air - 
CuO. 
The calculated spectral dependencies of reflection coef-
ficient from the interfaces between layers, that located 
one after another in a solar cell are presented in Fig. 2b. 
As expected, because of the low refractive index of light in 
the material we observe the lowest value of reflection 
coefficients at the interfaces ZnMgO-ZnO (R  1-2∙10 – 3) 
та ZnMgO-ITO (R  1-10∙10 – 3), and the biggest values at 
the interface ZnMgO-CuO (R  0.22-0.28). The value of R 
for interfaces air-ZnMgO and air-glass taking values 
(0.10-0.15) and (0.03-0.04), respectively. 
Apart from the absorption processes in solar cell lay-
ers, the transmittance of the light in CuO absorbing layer 
can be defined by the formula T  1 – R. So transmittance 
of the photovoltaic converter with a multilayer structure 
can be found by the formula [16, 19]: 
 
 
12 23 34 45
( ) (1 )(1 )(1 )(1 )T R R R R      , (3) 
 
where R12, R23, R34, R45 – reflection from the following 
interfaces: air-glass, glass-ZnO(ITO), ZnO(ITO)-
ZnMgO, ZnMgO-CuO. 
 
 
 
Fig. 2 – The spectral dependences of the reflection coefficient 
(R) for interfaces: air-glass (1), air-ZnMgO (2), air-ZnO (3) air-
ITO (4) air-CuO (5) (a) and ZnMgO-CuO (1) glass-ZnO (2) 
glass-ITO (3), ITO-ZnMgO (4), ZnO-ZnMgO (5) (b) 
 
It should be noted that this equation does not ac-
count for multiple reflections in the glass plate, 
ZnO (ITO) and CuO layers, which is quite acceptable 
because of the small difference of reflection coefficients 
at the interfaces (Fig. 2b). It also allows us to ignore 
interference effects. 
 
 
 
Fig. 3 – Spectral dependence transmittance T() and reflec-
tance R() of a solar cell with ITO / ZnMgO / CuO (1) and 
ZnO / ZnMgO / CuO (2) structures. The reflection of light from 
the interphase interfaces was taking into account 
 
Fig. 3 shows the dependence of the transmission T 
and reflection R of the wavelength  considered for the 
solar converter. Solar cells based on n-ZnMgO / p-CuO 
heterojunction as with the ZnO as well as with ITO 
layer have very high-value of light transmission coeffi-
 THE PERFORMANCE OPTIMIZATION OF THIN-FILM SOLAR CONVERTERS … J. NANO- ELECTRON. PHYS. 9, 04002 (2017) 
 
 
04002-3 
cient ( 90 %), which affects their efficiency of convert-
ing solar energy into electricity. As shown in Fig. 4, the 
transmittance of ZnO layer is very close to the values 
obtained for the device containing ITO. 
To determine the optimal material of conductive 
layer solar cell was calculated a so-called coefficient of 
optical power loss of the device. It was determined by 
the formula: 
 
 
max
1
max
1
( ) ( )
( )
n
i
i
T T
n
T
 






, (4) 
 
Knowing that Tmax()  1, then expression (4) is 
simplified to the form: 
 
 
1
1
1 ( )
n
i
i
η T λ
n 
   , (5) 
 
The results of calculation of the coefficient of optical 
power loss in the solar cells with various structure are 
presented in Table 1. 
 
Table 1 – Coefficients of optical power loss in the solar cells 
 
Structure of solar 
cell 
Optical power loss 
coefficient, % 
The coefficient of 
light passing, % 
ITO/ZnMgO/CuO 8.45 91.55 
ZnO/ZnMgO/CuO 9.52 90.48 
 
As the table shows, the optical loss in the structures 
ITO / ZnMgO / CuO and ZnO / ZnMgO / CuO differ by 
only 1.07 %. But the best value of passage of light to 
the absorber layer has a structure with ITO (91.55 %). 
 
2.2 The Losses of Light Absorption in Solar Cell 
Layers 
 
In addition to losses on light reflection from layers 
should take into account the optical losses on light absorp-
tion in the auxiliary layers for solar converters. The 
transmittance coefficient of a multilayer structure in view 
of losses of reflection and absorption at all layers of the 
solar cell can be calculated using the expression [20]: 
 
1 1 2 2
12 23 34 45
( ) (1 )(1 )(1 )(1 )( )( )d dT R R R R e e         (6) 
 
where 1, 2 – are absorption coefficients of the materi-
als of the window and the conductive layer; d1, d2 – the 
thicknesses of these layers. 
The absorption coefficient of solar radiation () in 
view it's extinction coefficient as a function of wave-
length k() is calculated by the following equation: 
 
 
4
( ) k

 

 . (7) 
 
Fig. 4 shows the dependence of T on the wavelength 
 for solar cell based on n-ZnO / p-CuO heterojunction 
including losses on light absorption in the auxiliary 
layers with different thickness values. Analysis of the 
dependencies indicates that changing the thickness of 
30 to 400 nm of ZnMgO layer somewhat reduces the 
value of transmittance solar converter. It is established 
that an increase the thickness of the layer from 
d  30 nm to d  400 nm the optical losses increase for 
the device with a layer of ITO by 2.16 % при dITO  100 
nm and 0.92 % at dITO  200 nm. For the solar cell with 
a layer of ZnO, the loss value increased to 2.14 % at 
dZnO  100 nm and to 0.9 % at dZnO  200 nm. At the 
same time transmittance values of the device with ITO  
 
 
 
Fig. 4 – Spectral transmittance coefficients of multilayer struc-
tures glass / ITO / ZnMgO / CuO and glass / ZnO / ZnMgO / CuO 
at ZnMgO thickness: 30-400 nm and ITO (ZnO): 100 nm (a) and 
200 nm (b) 
 
 
 
Fig. 5 – Dependence of losses of light for structures 
glass / ITO / ZnMgO / CuO (solid lines) and 
glass / ZnO / ZnMgO / CuO (dotted lines) at thickness of ITO 
(ZnO): 100 nm (a) and 200 nm (b) 
 
layer is somewhat greater than the corresponding val-
ue for the structure with ZnO layer. 
Thus, calculations show that a layer of ITO is more 
attractive compared with ZnO for use in solar cells 
because improves the volume of a passage of light to 
the CuO absorber layer. 
 O.V. DIACHENKO, A.S. OPANASYUK, ET AL. J. NANO- ELECTRON. PHYS. 9, 04002 (2017) 
 
 
04002-4 
3. CONCLUSIONS 
 
In the paper, the optical losses were defined in thin 
film solar converters based on n-ZnMgO / p-CuO hetero-
junction with frontal contacts ZnO and ITO. Such solar 
cells have a very high value of light transmittance 
( 90 %) as in the case of the conductive layer of ZnO as 
well as ITO. 
It is established that the value of transmittance device 
with a layer of ITO by 1.07 % higher than the correspond-
ing values obtained for the structure with ZnO layer. 
The summary (optical and recombination) losses of 
the solar converter with different structures at 
dZnMgO  30 nm is equaled 14.26 % and 18.70 % for ZnO 
and ITO respectively. 
On the basis of calculations, it is possible to optimize 
the structure of photovoltaic converter minimizing these 
losses. 
 
AKNOWLEDGEMENTS 
 
This research was supported by the Ministry of Edu-
cation and Science of Ukraine (Grant No. 0116U002619, 
No. 0115U000665c, No. 0116U006813). 
 
 
REFERENCES 
 
1. H. Kidowaki, T. Oku, T. Akiyama, Int. J. Res. Rev. 
Appl. Sci. 13, 67 (2012). 
2. V. Kumar, S. Masudi-Panah, C. C. Tan, T. K. S. Wong, 
D. Z. Chi, and G. K. Dalapati, 2013 IEEE 5th Internation-
al Nanoelectronics Conference (INEC), 443 (Singapore: 
2013). 
3. R. Wick, S.D. Tilley, J. Phys. Chem. C 119, 26243 (2015). 
4. Y. Nishi, T. Miyata, J. Nomoto, T. Minami, 2011 37th 
IEEE Photovoltaic Specialists Conference, 266 (Washing-
ton: 2011). 
5. Y. Ievskaya, R.L.Z. Hoye, A. Sadhanala, K.P. Musselman, 
J.L. MacManus-Driscoll, Sol. Energy Mater. Sol. C. 135, 
43 (2015). 
6. A. Bhaumik, A. Haque, P. Karnati, M.F.N. Taufique, 
R. Patel, K. Ghosh, Thin Solid Films 572, 126 (2014). 
7. S.S. Wilson, J.P. Bosco, Y. Tolstova, D.O. Scanlon, 
G.W. Watson, H.A. Atwater, J. Chem. Inf. Model. 53, 1689 
(2013). 
8. Y.-F. Lim, C.S. Chua, C.J.J. Lee, D. Chi, Phys. Chem. 
Chem. Phys. 16, 25928 (2014). 
9. T. Oku, R. Motoyoshi, K. Fujimoto, T. Akiyama, 
B. Jeyadevan, J. Cuya, J. Phys. Chem. Solids 72, 1206 
(2011). 
10. A. Rios-Flores, O. Arés, J. Camacho, V. Rejon, J. Peña, 
Sol. Energy 86, 780 (2012). 
11. R. Scheer, H.W. Schock, Chalcogenide Photovoltaics: 
Physics, Technologies, and Thin Film Devices (Weinheim: 
Wiley-VCH: 2011). 
12. O.L. Lisitski, M.E. Kumekov, S.E. Kumekov, E.I. Terukov, 
Semiconductors 43, 765 (2009). 
13. S.R. Adilov, M.E. Kumekov, S.E. Kumekov, E.I. Terukov, 
Semiconductors 47, 655 (2013). 
14. T. Wong, S. Zhuk, S. Masudy-Panah, G. Dalapati, 
Materials 9, 271 (2016). 
15. H. Tampo, H. Shibata, K. Maejima, T.-W. Chiu, H. Itoh, 
A. Yamada, K. Matsubara, P. Fons, Y. Chiba, 
T. Wakamatsu, Y. Takeshita, H. Kanie, S. Niki, Appl. 
Phys. Lett. 94, 242107 (2009). 
16. O.A. Dobrozhan, A.S. Opanasyuk, V.V. Grynenko, 
J. Nano- Electron. Phys. 6, 04035 (2014). 
17. S.O. Kasap, Optoelectronics and Photonics: Principles and 
Practices (New Jersey: Prentice-Hall: 2001). 
18. Handbook of Physical Properties of Semiconductors 
(Ed. S. Adachi) (Boston: Kluwer Academic Publishers: 
2004). 
19. T. Mykytyuk, V. Roshko, L. Kosyachenko, Acta Phys. Pol. 
122, 1073 (2012). 
 


http://essuir.sumdu.edu.ua/bitstream/123456789/65510/1/Opanasyuk-84-85.pdf

The Performance Optimization of Thin-Film Solar Converters Based on n-ZnMgO / p-CuO Heterojunctions

Abstract

Similar works

Full text

Available Versions

Electronic Sumy State University Institutional Repository

Electronic Sumy State University Institutional Repository

SocioEconomic Challenges Journal (Sumy State University)

SocioEconomic Challenges Journal (Sumy State University)