Solar Cell Fabrication and Characterisation

  • A. A. Ojo
  • W. M. Cranton
  • I. M. Dharmadasa


This chapter provides an insight into next-generation graded bandgap photovoltaic device fabrication. All-electrodeposited devices were fabricated using n-p, n-n-p, n-n + large Schottky barrier (SB) and n-n-n + SB architecture using ZnS, CdS and CdTe thin layers. The fabricated devices were evaluated using both current-voltage (I-V) and capacitance-voltage (C-V) techniques. The inclusion of Ga into the regular CdCl2 post-growth treatment and the effect of pH were also explored with the improved result as compared to the regular CdCl2 PGT. Based on all experimental findings as explored within the limit of this work, the most promising of the configurations examined are the glass/FTO/n-CdS/n-CdTe/p-CdTe/Au with thicknesses of 120 nm (n-CdS), 1200 nm (n-CdTe), 30 nm (p-CdTe) and 100 nm (Au). The highest conversion efficiencies observed for two separate batches were 15.3 and 18.4%. The devices with the 18.4% efficiency showed some instability and therefore require further investigation. The glass/FTO/n-ZnS/n-CdS/n-CdTe/Au configuration with thicknesses of 50 nm (n-ZnS), 65 nm (n-CdS), 1200 nm (n-CdTe) and 100 nm (Au) also shows promising results with the highest efficiency achieved being 14.1% owing to bandgap grading strengths.


ZnS CdS CdTe All-electroplating of semiconductors Graded bandgap solar cells Shockley-Queisser limit 


  1. 1.
    I.M. Dharmadasa, Review of the CdCl2 treatment used in CdS/CdTe thin-film solar cell development and new evidence towards improved understanding. Coatings 4, 282–307 (2014). CrossRefGoogle Scholar
  2. 2.
    O.I. Olusola, Optoelectronic Devices Based on Graded Bandgap Structures Utilising Electroplated Semiconductors (Sheffield Hallam University, Sheffield, 2016)Google Scholar
  3. 3.
    H.I. Salim, Multilayer Solar Cells Based on CdTe Grown from Nitrate Precursor (Sheffield Hallam University, Sheffield, 2016)Google Scholar
  4. 4.
    O.K. Echendu, Thin-Film Solar Cells Using All-Electrodeposited ZnS, CdS and CdTe Materials (Sheffield Hallam University, Sheffield, 2014)Google Scholar
  5. 5.
    A. Bosio, N. Romeo, S. Mazzamuto, V. Canevari, Polycrystalline CdTe thin-films for photovoltaic applications. Prog. Cryst. Growth Charact. Mater. 52, 247–279 (2006). CrossRefGoogle Scholar
  6. 6.
    P. Fernández, Defect structure and luminescence properties of CdTe based compounds. J. Optoelectron. Adv. Mater. 5, 369–388 (2003)Google Scholar
  7. 7.
    I.M. Dharmadasa, Recent developments and progress on electrical contacts to CdTe, CdS and ZnSe with special reference to barrier contacts to CdTe. Prog. Cryst. Growth Charact. Mater. 36, 249–290 (1998). CrossRefGoogle Scholar
  8. 8.
    I.M. Dharmadasa, C.J. Blomfield, C.G. Scott, R. Coratger, F. Ajustron, J. Beauvillain, Metal/n-CdTe interfaces: a study of electrical contacts by deep level transient spectroscopy and ballistic electron emission microscopy. Solid State Electron. 42, 595–604 (1998). CrossRefGoogle Scholar
  9. 9.
    H.I. Salim, V. Patel, A. Abbas, J.M. Walls, I.M. Dharmadasa, Electrodeposition of CdTe thin-films using nitrate precursor for applications in solar cells, J. Mater. Sci. Mater. Electron. 26 (2015) 3119–3128. doi:
  10. 10.
    J.E. Granata, J.R. Sites, Effect of CdS thickness on CdS/CdTe quantum efficiency, in Conf. Rec. Twenty Fifth IEEE Photovolt. Spec. Conf. 1996 (2000), pp. 853–856.
  11. 11.
    W. Shockley, H.J. Queisser, Detailed balance limit of efficiency of p-n junction solar cells. J. Appl. Phys. 32, 510 (1961). CrossRefGoogle Scholar
  12. 12.
    A. De Vos, Detailed balance limit of the efficiency of tandem solar cells. J. Phys. D. Appl. Phys. 13, 839–846 (2000). CrossRefGoogle Scholar
  13. 13.
    J.S. Lee, Y.K. Jun, H.B. Im, Effects of CdS film thickness on the photovoltaic properties of sintered CdS / CdTe solar cells. J. Electrochem. Soc. 134, 248–251 (1987). CrossRefGoogle Scholar
  14. 14.
    S.G. Kumar, K.S.R.K. Rao, Physics and chemistry of CdTe/CdS thin-film heterojunction photovoltaic devices: fundamental and critical aspects. Energy Environ. Sci. 7, 45–102 (2014). CrossRefGoogle Scholar
  15. 15.
    I.M. Dharmadasa, Advances in Thin-Film Solar Cells (Pan Stanford, Singapore, 2013)Google Scholar
  16. 16.
    I.M. Dharmadasa, J.D. Bunning, A.P. Samantilleke, T. Shen, Effects of multi-defects at metal/semiconductor interfaces on electrical properties and their influence on stability and lifetime of thin-film solar cells. Sol. Energy Mater. Sol. Cells 86, 373–384 (2005). CrossRefGoogle Scholar
  17. 17.
    I.M. Dharmadasa, Third generation multi-layer tandem solar cells for achieving high conversion efficiencies. Sol. Energy Mater. Sol. Cells 85, 293–300 (2005). CrossRefGoogle Scholar
  18. 18.
    I.M. Dharmadasa, A.P. Samantilleke, N.B. Chaure, J. Young, New ways of developing glass/conducting glass/CdS/CdTe/metal thin-film solar cells based on a new model. Semicond. Sci. Technol. 17, 1238–1248 (2002). CrossRefGoogle Scholar
  19. 19.
    T. Soga, Nanostructured Materials for Solar Energy Conversion (Elsevier Science, 2006), p. 614.
  20. 20.
    C. Ni, P. Shah, A.M. Sarangan, Effects of different wetting layers on the growth of smooth ultra-thin silver thin-films, in ed. by E.M. Campo, E.A. Dobisz, L.A. Eldada (2014), p. 91700L.
  21. 21.
    T. Yasuda, K. Hara, H. Kukimoto, Low resistivity Al-doped ZnS grown by MOVPE. J. Cryst. Growth 77, 485–489 (1986). CrossRefGoogle Scholar
  22. 22.
    M.L. Madugu, O.I.-O. Olusola, O.K. Echendu, B. Kadem, I.M. Dharmadasa, Intrinsic doping in electrodeposited ZnS thin-films for application in large-area optoelectronic devices. J. Electron. Mater. 45, 2710–2717 (2016). CrossRefGoogle Scholar
  23. 23.
    T.L. Chu, S.S. Chu, Thin-film II–VI photovoltaics. Solid State Electron. 38, 533–549 (1995). CrossRefGoogle Scholar
  24. 24.
    O. Echendu, I. Dharmadasa, Graded-bandgap solar cells using all-electrodeposited ZnS, CdS and CdTe thin-films. Energies 8, 4416–4435 (2015). CrossRefGoogle Scholar
  25. 25.
    X. Liu, Y. Jiang, F. Fu, W. Guo, W. Huang, L. Li, Facile synthesis of high-quality ZnS, CdS, CdZnS, and CdZnS/ZnS core/shell quantum dots: characterization and diffusion mechanism. Mater. Sci. Semicond. Process. 16, 1723–1729 (2013). CrossRefGoogle Scholar
  26. 26.
    J.M. Woodcock, A.K. Turner, M.E. Ozsan, J.G. Summers, Thin-film solar cells based on electrodeposited CdTe, in Conf. Rec. Twenty-Second IEEE Photovolt. Spec. Conf.—1991, IEEE (1991), pp. 842–847.
  27. 27.
  28. 28.
    I.M. Dharmadasa, A.B. McLean, M.H. Patterson, R.H. Williams, Schottky barriers and interface reactions on chemically etched n-CdTe single crystals. Semicond. Sci. Technol. 2, 404–412 (1987). CrossRefGoogle Scholar
  29. 29.
    S. Tanaka, J.A. Bruce, M.S. Wrighton, Deliberate modification of the behavior of n-type cadmium telluride/electrolyte interfaces by surface etching. Removal of Fermi level pinning. J. Phys. Chem. 85, 3778–3787 (1981). CrossRefGoogle Scholar
  30. 30.
    I.M. Dharmadasa, O.K. Echendu, F. Fauzi, N.A. Abdul-Manaf, O.I. Olusola, H.I. Salim, M.L. Madugu, A.A. Ojo, Improvement of composition of CdTe thin-films during heat treatment in the presence of CdCl2. J. Mater. Sci. Mater. Electron. 28, 2343–2352 (2017). CrossRefGoogle Scholar
  31. 31.
    J. Britt, C. Ferekides, Thin-film CdS/CdTe solar cell with 15.8% efficiency. Appl. Phys. Lett. 62, 2851–2852 (1993). CrossRefGoogle Scholar
  32. 32.
    T. Potlog, L. Ghimpu, P. Gashin, A. Pudov, T. Nagle, J. Sites, Influence of annealing in different chlorides on the photovoltaic parameters of CdS/CdTe solar cells. Sol. Energy Mater. Sol. Cells 80, 327–334 (2003). CrossRefGoogle Scholar
  33. 33.
    N.A. Abdul-Manaf, A.R. Weerasinghe, O.K. Echendu, I.M. Dharmadasa, Electro-plating and characterisation of cadmium sulphide thin-films using ammonium thiosulphate as the sulphur source. J. Mater. Sci. Mater. Electron. 26, 2418–2429 (2015). CrossRefGoogle Scholar
  34. 34.
    B.E. McCandless, K.D. Dobson, Processing options for CdTe thin-film solar cells. Sol. Energy 77, 839–856 (2004). CrossRefGoogle Scholar
  35. 35.
    D.W. Lane, A review of the optical band gap of thin-film CdSxTe 1-x. Sol. Energy Mater. Sol. Cells 90, 1169–1175 (2006). CrossRefGoogle Scholar
  36. 36.
    D.A. Wood, K.D. Rogers, D.W. Lane, D.A. Wood, K.D. Rogers, J.A. Coath, Optical and structural characterization of CdS x Te 1- x thin-films for solar cell applications. J. Phys. Condens. Matter 12, 4433–4450 (2000). Scholar
  37. 37.
    E.Q.B. Macabebe, E.E. van Dyk, Parameter extraction from dark current–voltage characteristics of solar cells. S. Afr. J. Sci. 104, 401–404 (2008). Google Scholar
  38. 38.
    S.M. Sze, K.K. Ng, Physics of Semiconductor Devices (Wiley, Hoboken, 2006). CrossRefGoogle Scholar
  39. 39.
    K. Masuko, M. Shigematsu, T. Hashiguchi, D. Fujishima, M. Kai, N. Yoshimura, T. Yamaguchi, Y. Ichihashi, T. Mishima, N. Matsubara, T. Yamanishi, T. Takahama, M. Taguchi, E. Maruyama, S. Okamoto, Achievement of more than 25% conversion efficiency with crystalline silicon heterojunction solar cell. IEEE J. Photovoltaics 4, 1433–1435 (2014). CrossRefGoogle Scholar
  40. 40.
    B.M. Basol, Processing high efficiency CdTe solar cells. Int. J. Sol. Energy 12, 25–35 (1992). CrossRefGoogle Scholar
  41. 41.
    S. Mazzamuto, L. Vaillant, A. Bosio, N. Romeo, N. Armani, G. Salviati, A study of the CdTe treatment with a Freon gas such as CHF2Cl. Thin Solid Films 516, 7079–7083 (2008). CrossRefGoogle Scholar
  42. 42.
    J.D. Major, L. Bowen, R.E. Treharne, L.J. Phillips, K. Durose, NH 4 Cl alternative to the CdCl 2 treatment step for CdTe thin-film solar cells. IEEE J. 5, 386–389 (2015). CrossRefGoogle Scholar
  43. 43.
    B. Maniscalco, A. Abbas, J.W. Bowers, P.M. Kaminski, K. Bass, G. West, J.M. Walls, The activation of thin-film CdTe solar cells using alternative chlorine containing compounds. Thin Solid Films 582, 115–119 (2015). CrossRefGoogle Scholar
  44. 44.
    B.E. McCandless, I. Youm, R.W. Birkmire, Optimization of vapor post-deposition processing for evaporated CdS/CdTe solar cells. Prog. Photovolt. Res. Appl. 7, 21–30 (1999).<21::AID-PIP244>3.0.CO;2-D CrossRefGoogle Scholar
  45. 45.
    H. Bayhan, C. Ercelebi, Effects of post deposition treatments on vacuum evaporated CdTe thin-films and CdS/CdTe heterojunction devices. Turk. J. Phys. 22, 441–451 (1998). Google Scholar
  46. 46.
    I.M. Dharmadasa, J.M. Thornton, R.H. Williams, Effects of surface treatments on Schottky barrier formation at metal/n-type CdTe contacts. Appl. Phys. Lett. 54, 137 (1989). CrossRefGoogle Scholar
  47. 47.
    V. Krishnakumar, J. Han, A. Klein, W. Jaegermann, CdTe thin-film solar cells with reduced CdS film thickness. Thin Solid Films 519, 7138–7141 (2011). CrossRefGoogle Scholar
  48. 48.
    G. Carotenuto, M. Palomba, S. De Nicola, G. Ambrosone, U. Coscia, Structural and photoconductivity properties of tellurium/PMMA films. Nanoscale Res. Lett. 10, 1007 (2015). CrossRefGoogle Scholar
  49. 49.
    B. Abad, M. Rull-Bravo, S.L. Hodson, X. Xu, M. Martin-Gonzalez, Thermoelectric properties of electrodeposited tellurium films and the sodium lignosulfonate effect. Electrochim. Acta 169, 37–45 (2015). CrossRefGoogle Scholar
  50. 50.
    S. Chun, S. Lee, Y. Jung, J.S. Bae, J. Kim, D. Kim, Wet chemical etched CdTe thin-film solar cells. Curr. Appl. Phys. 13, 211–216 (2013). CrossRefGoogle Scholar
  51. 51.
    Z.H. Chen, C.P. Liu, H.E. Wang, Y.B. Tang, Z.T. Liu, W.J. Zhang, S.T. Lee, J.A. Zapien, I. Bello, Electronic structure at the interfaces of vertically aligned zinc oxide nanowires and sensitizing layers in photochemical solar cells. J. Phys. D. Appl. Phys. 44, 325108 (2011). CrossRefGoogle Scholar
  52. 52.
    Y. Shan, J.-J. Xu, H.-Y. Chen, Enhanced electrochemiluminescence quenching of CdS:Mn nanocrystals by CdTe QDs-doped silica nanoparticles for ultrasensitive detection of thrombin. Nanoscale 3, 2916 (2011). CrossRefGoogle Scholar
  53. 53.
    N.A. Abdul-Manaf, H.I. Salim, M.L. Madugu, O.I. Olusola, I.M. Dharmadasa, Electro-plating and characterisation of CdTe thin-films using CdCl2 as the cadmium source. Energies 8, 10883–10903 (2015). CrossRefGoogle Scholar
  54. 54.
    P.J. Sellin, A.W. Dazvies, A. Lohstroh, M.E. Özsan, J. Parkin, Drift mobility and mobility-lifetime products in CdTe:Cl grown by the travelling heater method. IEEE Trans. Nucl. Sci. 52, 3074–3078 (2005). CrossRefGoogle Scholar
  55. 55.
    J. Verschraegen, M. Burgelman, J. Penndorf, Temperature dependence of the diode ideality factor in CuInS2-on-Cu-tape solar cells. Thin Solid Films 480–481, 307–311 (2005). CrossRefGoogle Scholar
  56. 56.
    R.B. Godfrey, M.A. Green, Enhancement of MIS solar-cell “efficiency” by peripheral collection. Appl. Phys. Lett. 31, 705–707 (1977). CrossRefGoogle Scholar
  57. 57.
    I.M. Dharmadasa, A.A. Ojo, H.I. Salim, R. Dharmadasa, Next generation solar cells based on graded bandgap device structures utilising rod-type nano-materials. Energies 8, 5440–5458 (2015). CrossRefGoogle Scholar
  58. 58.
    D. Congreve, J. Lee, N. Thompson, E. Hontz, External quantum efficiency above 100% in a singlet-exciton-fission–based organic photovoltaic cell. Science 340, 334–337 (2013). CrossRefGoogle Scholar
  59. 59.
    N.J.L.K. Davis, M.L. Bohm, M. Tabachnyk, F. Wisnivesky-Rocca-Rivarola, T.C. Jellicoe, C. Ducati, B. Ehrler, N.C. Greenham, Multiple-exciton generation in lead selenide nanorod solar cells with external quantum efficiencies exceeding 120%. Nat. Commun. 6, 81–87 (2015). CrossRefGoogle Scholar
  60. 60.
    I. Strzalkowski, S. Joshi, C.R. Crowell, Dielectric constant and its temperature dependence for GaAs, CdTe, and ZnSe. Appl. Phys. Lett. 28, 350–352 (1976). CrossRefGoogle Scholar
  61. 61.
    B.M. Basol, B. McCandless, Brief review of cadmium telluride-based photovoltaic technologies. J. Photonics Energy. 4, 40996 (2014). CrossRefGoogle Scholar
  62. 62.
    M. Gloeckler, I. Sankin, Z. Zhao, CdTe solar cells at the threshold to 20% efficiency. IEEE J. Photovoltaics 3, 1389–1393 (2013). CrossRefGoogle Scholar
  63. 63.
    T.J. Coutts, S. Naseem, High efficiency indium tin oxide/indium phosphide solar cells. Appl. Phys. Lett. 46, 164–166 (1985). CrossRefGoogle Scholar
  64. 64.
    H. Liu, Y. Tian, Y. Zhang, K. Gao, K. Lu, R. Wu, D. Qin, H. Wu, Z. Peng, L. Hou, W. Huang, Solution processed CdTe/CdSe nanocrystal solar cells with more than 5.5% efficiency by using an inverted device structure. J. Mater. Chem. C 3, 4227–4234 (2015). CrossRefGoogle Scholar
  65. 65.
    H. Xue, R. Wu, Y. Xie, Q. Tan, D. Qin, H. Wu, W. Huang, Recent progress on solution-processed CdTe nanocrystals solar cells. Appl. Sci. 6, 197 (2016). CrossRefGoogle Scholar
  66. 66.
    I.M. Dharmadasa, O.K. Echendu, F. Fauzi, N.A. Abdul-Manaf, H.I. Salim, T. Druffel, R. Dharmadasa, B. Lavery, Effects of CdCl2 treatment on deep levels in CdTe and their implications on thin-film solar cells: a comprehensive photoluminescence study. J. Mater. Sci. Mater. Electron. 26, 4571–4583 (2015). CrossRefGoogle Scholar
  67. 67.
    N.V.V. Sochinskii, V.N.N. Babentsov, N.I.I. Tarbaev, M.D. Serrano, E. Dieguez, The low temperature annealing of p-cadmium telluride in gallium-bath. Mater. Res. Bull. 28, 1061–1066 (1993). CrossRefGoogle Scholar
  68. 68.
    J.C. Tranchart, P. Bach, A gas bearing system for the growth of CdTe. J. Cryst. Growth 32, 8–12 (1976). CrossRefGoogle Scholar
  69. 69.
    J. Han, C. Spanheimer, G. Haindl, G. Fu, V. Krishnakumar, J. Schaffner, C. Fan, K. Zhao, A. Klein, W. Jaegermann, Optimized chemical bath deposited CdS layers for the improvement of CdTe solar cells. Sol. Energy Mater. Sol. Cells 95, 816–820 (2011). CrossRefGoogle Scholar
  70. 70.
    T. Toyama, K. Matsune, H. Oda, M. Ohta, H. Okamoto, X-ray diffraction study of CdS/CdTe heterostructure for thin-film solar cell: influence of CdS grain size on subsequent growth of (111)-oriented CdTe film. J. Phys. D. Appl. Phys. 39, 1537–1542 (2006). CrossRefGoogle Scholar
  71. 71.
    I.M. Dharmadasa, P. Bingham, O.K. Echendu, H.I. Salim, T. Druffel, R. Dharmadasa, G. Sumanasekera, R. Dharmasena, M.B. Dergacheva, K. Mit, K. Urazov, L. Bowen, M. Walls, A. Abbas, Fabrication of CdS/CdTe-based thin-film solar cells using an electrochemical technique. Coatings 4, 380–415 (2014). CrossRefGoogle Scholar
  72. 72.
    A. Monshi, Modified Scherrer equation to estimate more accurately nano-crystallite size using XRD. World J. Nano Sci. Eng. 2, 154–160 (2012). CrossRefGoogle Scholar
  73. 73.
    T.M. Razykov, N. Amin, B. Ergashev, C.S. Ferekides, D.Y. Goswami, M.K. Hakkulov, K.M. Kouchkarov, K. Sopian, M.Y. Sulaiman, M. Alghoul, H.S. Ullal, Effect of CdCl2 treatment on physical properties of CdTe films with different compositions fabricated by chemical molecular beam deposition. Appl. Sol. Energy 49, 35–39 (2013). CrossRefGoogle Scholar
  74. 74.
    J.D. Major, R.E. Treharne, L.J. Phillips, K. Durose, A low-cost non-toxic post-growth activation step for CdTe solar cells. Nature 511, 334–337 (2014). CrossRefGoogle Scholar
  75. 75.
    T.L. Chu, S.S. Chu, C. Ferekides, J. Britt, C.Q. Wu, Thin-film junctions of cadmium telluride by metalorganic chemical vapor deposition. J. Appl. Phys. 71, 3870–3876 (1992). CrossRefGoogle Scholar
  76. 76.
    T. Ferid, M. Saji, Transport properties in gallium doped CdTe MOVPE layers. J. Cryst. Growth 172, 83–88 (1997). CrossRefGoogle Scholar
  77. 77.
    I.M. Dharmadasa, A.A. Ojo, Unravelling complex nature of CdS/CdTe based thin-film solar cells. J. Mater. Sci. Mater. Electron. 28, 16598–16617 (2017). CrossRefGoogle Scholar

Copyright information

© Springer International Publishing AG, part of Springer Nature 2019

Authors and Affiliations

  • A. A. Ojo
    • 1
  • W. M. Cranton
    • 1
  • I. M. Dharmadasa
    • 1
  1. 1.Sheffield Hallam UniversitySheffieldUK

Personalised recommendations