Skip to main content
SpringerLink
Log in

Investigation of TiO2 as the buffer layer in wide bandgap chalcopyrite solar cells using SCAPS

  • Published:
Journal of Materials Science: Materials in Electronics Aims and scope Submit manuscript

Abstract

The compound CuGaSe2 (CGS) is a potential wide bandgap semiconductor as a top cell for tandem solar cells in combination with a Cu(In,Ga)Se2 or Si bottom cell. However, the traditional cadmium sulfide (CdS) buffer layer usually forms a “cliff” structure at the heterojunction interface with CGS film, which deteriorates device performance of solar cell obviously. Herein, the non-toxic and wide bandgap TiO2 is studied as the n-type buffer layer of CGS thin film solar cell using SCAPS simulation software. First of all, the impact of different buffer layer thicknesses on the heterojunction interface is investigated systematically. It is found that the TiO2 buffer layer can reduce the conduction band offset (CBO) between the absorber layer and the buffer layer to about 0.03 eV, which can induce the photo-generated electrons across the interface barrier easily, and thus resulting an increase in device performance obviously. Further investigations on carrier concentrations of the buffer layer indicate high quality TiO2 buffer layer should have a lower carrier concentration below 2 × 1017 cm−3. This study offers a promising buffer layer material for CGS.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5

Similar content being viewed by others

Data availability

The data that support the findings of this study are available on request from the corresponding author.

References

  1. V. Bermudez, A. Perez-Rodriguez, Understanding the cell-to-module efficiency gap in Cu(In,Ga)(S,Se)2 photovoltaics scale-up. Nat Energy 3 (2018).

  2. K. Yoshikawa, H. Kawasaki, W. Yoshida, T. Irie, K. Konishi, K. Nakano, T. Uto, D. Adachi, M. Kanematsu, H. Uzu, K. Yamamoto, Silicon heterojunction solar cell with interdigitated back contacts for a photoconversion efficiency over 26%. Nat. Energy 2, 17032 (2017)

    Article  CAS  Google Scholar 

  3. S.R. Tamalampudi, Y.Y. Lu, U.R. Kumar, R. Sankar, C.D. Liao, B.K. Moorthy, C.H. Cheng, F.C. Chou, Y.T. Chen, High performance and bendable few-layered InSe photodetectors with broad spectral response. Nano Lett 14, 2800–2806 (2014)

    Article  CAS  Google Scholar 

  4. N. Liu, F. Xu, Y. Zhu, Y. Hu, G. Liu, L. Wu, K. Wu, S. Sun, F. Hong, Synthesis and characterization of (Cu1−xAgx)2ZnSnS4 nanoparticles with phase transition and bandgap tuning. J. Mater. Sci. 31, 5760–5768 (2020)

    CAS  Google Scholar 

  5. W. Witte, D. Abou-Ras, K. Albe, G.H. Bauer, F. Bertram, C. Boit, R. Brüggemann, J. Christen, J. Dietrich, A. Eicke, D. Hariskos, M. Maiberg, R. Mainz, M. Meessen, M. Müller, O. Neumann, T. Orgis, S. Paetel, J. Pohl, H. Rodriguez-Alvarez, R. Scheer, H.-W. Schock, T. Unold, A. Weber, M. Powalla, Gallium gradients in Cu(In, Ga)Se2 thin-film solar cells. Prog. Photovolt. Res. Appl. 23, 717–733 (2015)

    Article  CAS  Google Scholar 

  6. W.N. Shafarman, R. Klenk, B.E. McCandless, Device and material characterization of Cu(InGa)Se2 solar cells with increasing band gap. J. Appl. Phys. 79, 7324–7328 (1996)

    Article  CAS  Google Scholar 

  7. N. Bandaru, E. Panda, Influence of CIGS film thickness on the microstructure, bulk optoelectronic, and surface electrical properties. J. Mater. Sci. 32, 28618–28632 (2021)

    CAS  Google Scholar 

  8. S.V. Desarada, P.U. Londhe, S. Chaure, N.B. Chaure, CuInGaSe2 (CIGS) thin film on flexible Mo substrates from non-aqueous one-step electrodeposition process. J. Mater. Sci. (2021).

  9. M. Nakamura, K. Yamaguchi, Y. Kimoto, Y. Yasaki, T. Kato, H. Sugimoto, Cd-Free Cu(In, Ga)(Se, S)2 thin-film solar cell with record efficiency of 23.35%. IEEE J. Photovolt. 9, 1863–1867 (2019)

    Article  Google Scholar 

  10. M.A. Contreras, L.M. Mansfield, B. Egaas, J. Li, M. Romero, R. Noufi, E. Rudiger-Voigt, W. Mannstadt, Wide bandgap Cu(In, Ga)Se2 solar cells with improved energy conversion efficiency. Prog. Photovolt. Res. Appl. 20, 843–850 (2012)

    Article  CAS  Google Scholar 

  11. W. Li, W. Li, Y. Feng, C. Yang, Numerical analysis of the back interface for high efficiency wide band gap chalcopyrite solar cells. Sol. Energy 180, 207–215 (2019)

    Article  CAS  Google Scholar 

  12. M. Gloeckler, J.R. Sites, Efficiency limitations for wide-band-gap chalcopyrite solar cells. Thin Solid Films 480–481, 241–245 (2005)

    Article  Google Scholar 

  13. Y. Zhang, S. Lin, S. Cheng, Z. He, Z. Hu, Z. Zhou, W. Liu, Y. Sun, Boosting Cu(In, Ga)Se2 thin film growth in low-temperature rapid-deposition processes: an improved design for the single-heating Knudsen effusion cell. Engineering 7, 534–541 (2021)

    Article  CAS  Google Scholar 

  14. Y. Zhang, S. Lin, Z. Hu, S. Cheng, Z. He, Z. Zhou, S. Sun, W. Liu, Y. Sun, Towards an optimized gallium gradient for Cu(In, Ga)Se2 thin film via an improved constant low-temperature deposition process. Sol. Energy Mater. Sol. Cells 209, 110425 (2020)

    Article  CAS  Google Scholar 

  15. S. Siebentritt, E. Avancini, M. Bär, J. Bombsch, E. Bourgeois, S. Buecheler, R. Carron, C. Castro, S. Duguay, R. Félix, E. Handick, D. Hariskos, V. Havu, P. Jackson, H.-P. Komsa, T. Kunze, M. Malitckaya, R. Menozzi, M. Nesladek, N. Nicoara, M. Puska, M. Raghuwanshi, P. Pareige, S. Sadewasser, G. Sozzi, A.N. Tiwari, S. Ueda, A. Vilalta-Clemente, T.P. Weiss, F. Werner, R.G. Wilks, W. Witte, M.H. Wolter, Heavy alkali treatment of Cu(In, Ga)Se2 solar cells: surface versus bulk effects. Adv. Energy Mater. 10, 1903752 (2020)

    Article  CAS  Google Scholar 

  16. Y. Zhang, Z. Hu, S. Lin, C. Wang, S. Cheng, Z. He, Z. Zhou, Y. Sun, W. Liu, Silver surface treatment of Cu(In, Ga)Se2 (CIGS) thin film: a new passivation process for the CdS/CIGS heterojunction interface. Solar RRL 4, 2000290 (2020)

    Article  CAS  Google Scholar 

  17. J. Gong, Y. Kong, J. Li, K. Wang, X. Wang, Z. Zhang, Z. Ding, X. Xiao, Enhancing photocurrent of Cu(In, Ga)Se2 solar cells with actively controlled Ga grading in the absorber layer. Nano Energy 62, 205–211 (2019)

    Article  CAS  Google Scholar 

  18. J. Chantana, D. Hironiwa, T. Watanabe, S. Teraji, K. Kawamura, T. Minemoto, Controlled back slope of Ga/(In+Ga) profile in Cu(In, Ga)Se2 absorber fabricated by multi layer precursor method for improvement of its photovoltaic performance. Sol. Energy Mater. Sol. Cells 133, 223–228 (2015)

    Article  CAS  Google Scholar 

  19. Y. Liu, B. Li, S. Lin, W. Liu, J. Adam, M. Madsen, H.-G. Rubahn, Y. Sun, Numerical analysis on effects of experimental Ga grading on Cu(In, Ga)Se2 solar cell performance. J. Phys. Chem. Solids 120, 190–196 (2018)

    Article  CAS  Google Scholar 

  20. A. Aissat, H. Arbouz, J.P. Vilcot, Optimization and improvement of a front graded bandgap CuInGaSe2 solar cell. Sol. Energy Mater. Sol. Cells 180, 381–385 (2018)

    Article  CAS  Google Scholar 

  21. A. Sharan, F.P. Sabino, A. Janotti, N. Gaillard, T. Ogitsu, J.B. Varley, Assessing the roles of Cu- and Ag-deficient layers in chalcopyrite-based solar cells through first principles calculations. J. Appl. Phys. 127, 065303 (2020)

    Article  CAS  Google Scholar 

  22. N. Valdes, J. Lee, W. Shafarman, Comparison of Ag and Ga alloying in low bandgap CuInSe2-based solar cells. Sol. Energy Mater. Sol. Cells 195, 155–159 (2019)

    Article  CAS  Google Scholar 

  23. V. Achard, M. Balestrieri, S. Béchu, M. Bouttemy, M. Jubault, T. Hildebrandt, L. Lombez, N. Naghavi, A. Etcheberry, D. Lincot, F. Donsanti, Study of gallium front grading at low deposition temperature on polyimide substrates and impacts on the solar cell properties. IEEE J. Photovolt. 1–6 (2018).

  24. J. Chantana, T. Watanabe, S. Teraji, T. Minemoto, Influence of minimum position in [Ga]/([Ga]+[In]) profile of Cu(In, Ga)Se 2 on flexible stainless steel substrate on its photovoltaic performances. Sol. Energy Mater. Sol. Cells 157, 750–756 (2016)

    Article  CAS  Google Scholar 

  25. X. Zhang, Z.K. Yuan, S. Chen, Low electron carrier concentration near the p-n junction interface: a fundamental factor limiting short-circuit current of Cu(In, Ga)Se2 solar cells. Sol. RRL 3, 1900057 (2019)

    Article  Google Scholar 

  26. Y. Zhao, S. Yuan, D. Kou, Z. Zhou, X. Wang, H. Xiao, Y. Deng, C. Cui, Q. Chang, S. Wu, High efficiency CIGS solar cells by bulk defect passivation through Ag substituting strategy. ACS Appl. Mater. Interfaces. 12, 12717–12726 (2020)

    Article  CAS  Google Scholar 

  27. M. Ballabio, D. Fuertes Marron, N. Barreau, M. Bonn, E. Canovas, composition-dependent passivation efficiency at the CdS/CuIn1 − xGaxSe2 interface, Adv. Mater. e1907763 (2020).

  28. R. Scheer, Activation energy of heterojunction diode currents in the limit of interface recombination. J. Appl. Phys. 105, 104505 (2009)

    Article  Google Scholar 

  29. W. Hsu, C.M. Sutter-Fella, M. Hettick, L. Cheng, S. Chan, Y. Chen, Y. Zeng, M. Zheng, H.P. Wang, C.C. Chiang, A. Javey, Electron-selective TiO2 contact for Cu(In, Ga)Se2 solar cells. Sci. Rep. 5, 16028 (2015)

    Article  CAS  Google Scholar 

  30. T.-M. Cheng, C.-H. Cai, W.-C. Huang, W.-L. Xu, L.-H. Tu, C.-H. Lai, Efficiency enhancement of Cu(In, Ga)(S, Se)2 solar cells by indium-doped CdS buffer layers. ACS Appl. Mater. Interfaces. 12, 18157–18164 (2020)

    Article  CAS  Google Scholar 

  31. J. Keller, L. Stolt, K.V. Sopiha, J.K. Larsen, L. Riekehr, M. Edoff, On the paramount role of absorber stoichiometry in (Ag, Cu)(In, Ga)Se2 wide-gap solar cells. Sol. RRL 4, 2000508 (2020)

    Article  CAS  Google Scholar 

  32. T. Nietzold, N. Valdes, M.E. Stuckelberger, M. Chiu, T. Walker, A.M. Jeffries, A. Sinha, L.T. Schelhas, B. Lai, W.N. Shafarman, M.I. Bertoni, Role of cation ordering on device performance in (Ag, Cu)InSe2 solar cells with KF post-deposition treatment. ACS Appl. Energy Mater. 4, 233–241 (2021)

    Article  CAS  Google Scholar 

  33. A. Chirila, S. Buecheler, F. Pianezzi, P. Bloesch, C. Gretener, A.R. Uhl, C. Fella, L. Kranz, J. Perrenoud, S. Seyrling, R. Verma, S. Nishiwaki, Y.E. Romanyuk, G. Bilger, A.N. Tiwari, Highly efficient Cu(In, Ga)Se2 solar cells grown on flexible polymer films. Nat. Mater. 10, 857–861 (2011)

    Article  CAS  Google Scholar 

  34. J. Löckinger, S. Nishiwaki, T.P. Weiss, B. Bissig, Y.E. Romanyuk, S. Buecheler, A.N. Tiwari, TiO2 as intermediate buffer layer in Cu(In, Ga)Se2 solar cells. Sol. Energy Mater. Sol. Cells 174, 397–404 (2018)

    Article  Google Scholar 

  35. S. Ishizuka, Impact of Cu-deficient p-n heterointerface in CuGaSe2 photovoltaic devices. Appl. Phys. Lett. 118, 133901 (2021)

    Article  CAS  Google Scholar 

  36. Y. Zhang, Y. Zhang, X. Chen, S. Wang, Q. Gao, M. Wu, Z. Wang, J. Ao, Y. Sun, W. Liu, Q. Zhang, Ammonia-induced surface microstructure reconstruction on ACIGS thin film at room temperature. Mater. Sci. Semicond. Process. 140, 106380 (2022)

    Article  CAS  Google Scholar 

  37. N.E.I. Boukortt, S. Patanè, M. Adouane, R. AlHammadi, Numerical optimization of ultrathin CIGS solar cells with rear surface passivation. Sol. Energy 220, 590–597 (2021)

    Article  CAS  Google Scholar 

  38. H. Heriche, Z. Rouabah, N. Bouarissa, New ultra thin CIGS structure solar cells using SCAPS simulation program. Int. J. Hydrogen Energy 42, 9524–9532 (2017)

    Article  CAS  Google Scholar 

  39. A. Chihi, M.F. Boujmil, B. Bessais, Investigation on the performance of CIGS/TiO2 heterojunction using SCAPS software for highly efficient solar cells. J. Electron. Mater. 46, 5270–5277 (2017)

    Article  CAS  Google Scholar 

  40. Y. Zhang, L. Shi, Z. Wang, H. Dai, Z. Hu, S. Zhou, H. Chen, X. Feng, J. Zhu, Y. Sun, W. Liu, Q. Zhang, Silver-assisted optimization of band gap gradient structure of Cu(In, Ga)Se2 solar cells via SCAPS. Sol. Energy 227, 334–342 (2021)

    Article  CAS  Google Scholar 

  41. S. Tripathi, P. Sadanand, D.K. Lohia, Dwivedi, Contribution to sustainable and environmental friendly non-toxic CZTS solar cell with an innovative hybrid buffer layer. Sol. Energy 204, 748–760 (2020)

    Article  CAS  Google Scholar 

  42. P.K. Sadanand, S. Singh, P. Rai, D.K. Lohia, Dwivedi, Comparative study of the CZTS, CuSbS2 and CuSbSe2 solar photovoltaic cell with an earth-abundant non-toxic buffer layer. Sol. Energy 222, 175–185 (2021)

    Article  CAS  Google Scholar 

  43. T. Umehara, F.A.B.M. Zulkifly, K. Nakada, A. Yamada, Conduction band offset engineering in wide-bandgap Ag(In, Ga)Se2 solar cells by hybrid buffer layer. Jpn. J. Appl. Phys. 56, 08MC09 (2017)

    Article  Google Scholar 

  44. T.-Y. Lin, I. Khatri, J. Matsuura, K. Shudo, W.-C. Huang, M. Sugiyama, C.-H. Lai, T. Nakada, Alkali-induced grain boundary reconstruction on Cu(In, Ga)Se2 thin film solar cells using cesium fluoride post deposition treatment. Nano Energy 68, 104299 (2020)

    Article  CAS  Google Scholar 

  45. D.-H. Cho, W.-J. Lee, M.E. Kim, K. Kim, J.H. Yun, Y.-D. Chung, Reactively sputtered Zn(O, S) buffer layers for controlling band alignment of Cu(In, Ga)Se2 thin-film solar cell interface. J. Alloys Compd. 842, 155986 (2020)

    Article  CAS  Google Scholar 

Download references

Acknowledgements

The authors gratefully acknowledge Dr. Marc Burgelman, University of Gent, Belgium, for providing the SCAPS simulation software.

Author information

Authors and Affiliations

  1. Class 23, Senior Two Student, Jiangsu Huaiyin Middle School, Huaian, 223399, People’s Republic of China

    Xuhui Liu

  2. Jiangsu Huaiyin Middle School, Huaian, 223399, People’s Republic of China

    Yong Hu

Authors
  1. Xuhui Liu
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Yong Hu
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

XL: conceptualization, methodology, investigation, writing—original draft. YH: writing—review and editing, resources.

Corresponding author

Correspondence to Yong Hu.

Ethics declarations

Conflict of interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Ethical approval

This article does not contain any studies with human participants or animals performed by any of the authors.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Liu, X., Hu, Y. Investigation of TiO2 as the buffer layer in wide bandgap chalcopyrite solar cells using SCAPS. J Mater Sci: Mater Electron 33, 6253–6261 (2022). https://doi.org/10.1007/s10854-022-07799-5

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s10854-022-07799-5

Search

Navigation