Abstract
Kesterite Cu2ZnSn(S, Se)4 (CZTSSe) solar cells are highly promising low-cost thin-film photovoltaics. However, the efficiency of these solar cells is challenged by severe charge losses and complex defects. Here we reveal through a data-driven correlation analysis that the dominant deep defect in CZTSSe exhibits a donor character. We further propose that incomplete cation exchange in the multi-step crystallization reactions of CZTSSe is the kinetic mechanism responsible for the defect formation. To facilitate the cation exchange, we introduce a multi-elemental alloying approach aimed at weakening the metal–chalcogen bond strength and the stability of intermediate phases. This strategy leads to a significant reduction in charge losses within the CZTSSe absorber and to a total-area cell efficiency of 14.6% (certified at 14.2%). Overall, these results not only present a significant advancement for kesterite solar cells but could also help identify and regulate defects in photovoltaic materials.
This is a preview of subscription content, access via your institution
Access options
Access Nature and 54 other Nature Portfolio journals
Get Nature+, our best-value online-access subscription
$29.99 / 30 days
cancel any time
Subscribe to this journal
Receive 12 digital issues and online access to articles
$119.00 per year
only $9.92 per issue
Buy this article
- Purchase on SpringerLink
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
Data availability
The data supporting the findings of this study are available within the main text, Supplementary Information and source data files. The structures used in the theoretical modelling are provided as Supplementary Datasets. Source data are provided with this paper.
References
Polman, A., Knight, M., Garnett, E. C., Ehrler, B. & Sinke, W. C. Photovoltaic materials: present efficiencies and future challenges. Science 352, aad4424 (2016).
Park, J. S., Kim, S., Xie, Z. & Walsh, A. Point defect engineering in thin-film solar cells. Nat. Rev. Mater. 3, 194–210 (2018).
Mitzi, D. B., Gunawan, O., Todorov, T. K., Wang, K. & Guha, S. The path towards a high-performance solution-processed kesterite solar cell. Sol. Energy Mater. Sol. Cells 95, 1421–1436 (2011).
Siebentritt, S. & Schorr, S. Kesterites—a challenging material for solar cells. Prog. Photovoltaics Res. Appl. 20, 512–519 (2012).
Gong, Y. et al. Elemental de-mixing-induced epitaxial kesterite/CdS interface enabling 13%-efficiency kesterite solar cells. Nat. Energy 7, 966–977 (2022).
Antunez, P. D., Bishop, D. M., Luo, Y. & Haight, R. Efficient kesterite solar cells with high open-circuit voltage for applications in powering distributed devices. Nat. Energy 2, 884–890 (2017).
Li, J. et al. Unveiling microscopic carrier loss mechanisms in 12% efficient Cu2ZnSnSe4 solar cells. Nat. Energy 7, 754–764 (2022).
Chen, S., Walsh, A., Gong, X.-G. & Wei, S.-H. Classification of lattice defects in the kesterite Cu2ZnSnS4 and Cu2ZnSnSe4 Earth-abundant solar cell absorbers. Adv. Mater. 25, 1522–1539 (2013).
Kim, S., Márquez, J. A., Unold, T. & Walsh, A. Upper limit to the photovoltaic efficiency of imperfect crystals from first principles. Energy Environ. Sci. 13, 1481–1491 (2020).
Larramona, G. et al. Fine-tuning the Sn content in CZTSSe thin films to achieve 10.8% solar cell efficiency from spray-deposited water–ethanol-based colloidal inks. Adv. Energy Mater. 5, 1501404 (2015).
Yuan, Z. et al. Engineering solar cell absorbers by exploring the band alignment and defect disparity: the case of Cu- and Ag-based kesterite compounds. Adv. Funct. Mater. 25, 6733–6743 (2015).
Gong, Y. et al. Ag incorporation with controlled grain growth enables 12.5% efficient kesterite solar cell with open circuit voltage reached 64.2% Shockley–Queisser limit. Adv. Funct. Mater. 31, 2101927 (2021).
Du, Y. et al. Defect engineering in Earth-abundant Cu2ZnSn(S,Se)4 photovoltaic materials via Ga3+-doping for over 12% efficient solar cells. Adv. Funct. Mater. 31, 2010325 (2021).
Wang, W. et al. Device characteristics of CZTSSe thin-film solar cells with 12.6% efficiency. Adv. Energy Mater. 4, 1301465 (2014).
Son, D.-H. et al. Effect of solid-H2S gas reactions on CZTSSe thin film growth and photovoltaic properties of a 12.62% efficiency device. J. Mater. Chem. A 7, 25279–25289 (2019).
Li, J. et al. Defect control for 12.5% efficiency Cu2ZnSnSe4 kesterite thin-film solar cells by engineering of local chemical environment. Adv. Mater. 32, 2005268 (2020).
Su, Z. et al. Device postannealing enabling over 12% efficient solution-processed Cu2ZnSnS4 solar cells with Cd2+ substitution. Adv. Mater. 32, 2000121 (2020).
Guo, H. et al. Band-gap-graded Cu2ZnSn(S,Se)4 drives highly efficient solar cells. Energy Environ. Sci. 15, 693–704 (2022).
Zhou, J. et al. Control of the phase evolution of kesterite by tuning of the selenium partial pressure for solar cells with 13.8% certified efficiency. Nat. Energy 8, 526–535 (2023).
Bourdais, S. et al. Is the Cu/Zn disorder the main culprit for the voltage deficit in kesterite solar cells? Adv. Energy Mater. 6, 1502276 (2016).
Duan, B. et al. Underlying mechanism of the efficiency loss in CZTSSe solar cells: disorder and deep defects. Sci. China Mater. 63, 2371–2396 (2020).
He, M. et al. Kesterite solar cells: insights into current strategies and challenges. Adv. Sci. 8, 2004313 (2021).
Yoo, H. et al. Investigation of the solid state reactions by time-resolved X-ray diffraction while crystallizing kesterite Cu2ZnSnSe4 thin films. Thin Solid Films 535, 73–77 (2013).
Gunawan, O., Todorov, T. K. & Mitzi, D. B. Loss mechanisms in hydrazine-processed Cu2ZnSn(Se,S)4 solar cells. Appl. Phys. Lett. 97, 233506 (2010).
Kumar, A. & Thakur, A. D. Comprehensive loss modeling in Cu2ZnSnS4 solar cells. Curr. Appl. Phys. 19, 1111–1119 (2019).
Xu, X. et al. Efficient and composition-tolerant kesterite Cu2ZnSn(S, Se)4 solar cells derived from an in situ formed multifunctional carbon framework. Adv. Energy Mater. 11, 2102298 (2021).
Zhou, J. et al. Regulating crystal growth via organic lithium salt additive for efficient kesterite solar cells. Nano Energy 89, 106405 (2021).
Levcenko, S. et al. Deep defects in Cu2ZnSn(S,Se)4 solar cells with varying Se content. Phys. Rev. Appl. 5, 024004 (2016).
Kim, S., Park, J. S. & Walsh, A. Identification of killer defects in kesterite thin-film solar cells. ACS Energy Lett. 3, 496–500 (2018).
Xu, Y., Yang, J., Chen, S. & Gong, X. G. Defect-assisted nonradiative recombination in Cu2ZnSnSe4: a comparative study with Cu2ZnSnS4. Phys. Rev. Mater. 5, 025403 (2021).
Yin, X., Tang, C., Sun, L., Shen, Z. & Gong, H. Study on phase formation mechanism of non- and near-stoichiometric Cu2ZnSn(S,Se)4 film prepared by selenization of Cu−Sn−Zn−S precursors. Chem. Mater. 26, 2005–2014 (2014).
Hages, C. J., Koeper, M. J., Miskin, C. K., Brew, K. W. & Agrawal, R. Controlled grain growth for high performance nanoparticle-based kesterite solar cells. Chem. Mater. 28, 7703–7714 (2016).
Giraldo, S. et al. How small amounts of Ge modify the formation pathways and crystallization of kesterites. Energy Environ. Sci. 11, 582–593 (2018).
Hsu, W. C., Bob, B., Yang, W., Chung, C. H. & Yang, Y. Reaction pathways for the formation of Cu2ZnSn(Se,S)4 absorber materials from liquid-phase hydrazine-based precursor inks. Energy Environ. Sci. 5, 8564–8571 (2012).
Goodenough, J. B. Electronic and ionic transport properties and other physical aspects of perovskites. Rep. Prog. Phys. 67, 1915–1993 (2004).
Cheng, Y. Q. & Ma, E. Atomic-level structure and structure–property relationship in metallic glasses. Prog. Mater. Sci. 56, 379–473 (2011).
Liu, M. & Meng, S. Atomly Modernize the Materials Science (Chinese Academy of Sciences, 2020); https://atomly.net/#/matdata
Liu, M. & Meng, S. Atomly.net materials database and its application in inorganic chemistry. Sci. Sin. Chim. 53, 19–25 (2023).
Hasaneen, M. F., Ali, H. M., Abd El-Raheem, M. M. & Abdel Hakeem, A. M. Structure and optical properties of thermally evaporated Te doped ZnSe thin films. Mater. Sci. Eng. B 262, 114704 (2020).
Paier, J., Asahi, R., Nagoya, A. & Kresse, G. Cu2ZnSnS4 as a potential photovoltaic material: a hybrid Hartree-Fock density functional theory study. Phys. Rev. B 79, 115126 (2009).
Yee, Y. S., Magyari-Köpe, B., Nishi, Y., Bent, S. F. & Clemens, B. M. Deep recombination centers in Cu2ZnSnSe4 revealed by screened-exchange hybrid density functional theory. Phys. Rev. B 92, 195201 (2015).
Walter, T., Herberholz, R., Müller, C. & Schock, H. W. Determination of defect distributions from admittance measurements and application to Cu(In,Ga)Se2 based heterojunctions. J. Appl. Phys. 80, 4411–4420 (1996).
Shi, J., Li, D., Luo, Y., Wu, H. & Meng, Q. Opto-electro-modulated transient photovoltage and photocurrent system for investigation of charge transport and recombination in solar cells. Rev. Sci. Instrum. 87, 123107 (2016).
Li, Y. et al. Exploiting electrical transients to quantify charge loss in solar cells. Joule 4, 472–489 (2020).
Luckert, F. et al. Optical properties of high quality Cu2ZnSnSe4 thin films. Appl. Phys. Lett. 99, 062104 (2011).
Tennyson, E. M. et al. Nanoimaging of open-circuit voltage in photovoltaic devices. Adv. Energy Mater. 5, 1501142 (2015).
Kang, Z. et al. Kelvin probe force microscopy for perovskite solar cells. Sci. Chin. Mater. 62, 776–789 (2019).
Teymur, B. et al. Top stack optimization for Cu2BaSn(S, Se)4 photovoltaic cell leads to improved device power conversion efficiency beyond 6%. Adv. Energy Mater. 12, 2201602 (2022).
Zhu, H., Kalkan, A. K., Hou, J. Y. & Fonash, S. J. Applications of AMPS-1D for solar cell simulation. AIP Conf. Proc. 462, 309–314 (1999).
Liu, Y., Sun, Y. & Rockett, A. A new simulation software of solar cells—WxAMPS. Sol. Energy Mater. Sol. Cells 98, 124–128 (2012).
Clark, S. J. et al. First principles methods using CASTEP. Z. Kristallogr. 220, 567–570 (2005).
Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865–3868 (1996).
Baroni, S., de Gironcoli, S., Corso, A. D. & Giannozzi, P. Phonons and related crystal properties from density-functional perturbation theory. Rev. Mod. Phys. 73, 515–562 (2001).
Wang, Y. et al. Cation disorder engineering yields AgBiS2 nanocrystals with enhanced optical absorption for efficient ultrathin solar cells. Nat. Photon. 16, 235–241 (2022).
Zhao, Y. et al. Regulating deposition kinetics via a novel additive-assisted chemical bath deposition technology enables fabrication of 10.57%-efficiency Sb2Se3 solar cells. Energy Environ. Sci. 15, 5118–5128 (2022).
Chen, X. et al. Solvent-assisted hydrothermal deposition approach for highly-efficient Sb2(S,Se)3 thin-film solar cells. Adv. Energy Mater. 13, 2300391 (2023).
Yan, C. et al. Cu2ZnSnS4 solar cells with over 10% power conversion efficiency enabled by heterojunction heat treatment. Nat. Energy 3, 764–772 (2018).
Acknowledgements
We acknowledge the Excellent Science and Technology Innovation Group of Jiangsu Province in Nanjing University of Science and Technology for their help in the theoretical calculations and appreciate the valuable help from B. Yang and Z. Li at Hebei University in the deep level transient spectroscopy measurements. This work is supported by the National Natural Science Foundation of China (numbers 52222212 (J.S.), U2002216 (Q.M.), 52227803 (Q.M.), 51972332 (H.W.), 52172261 (Y.L.), 52103284 (F.M.)). J.S. sincerely appreciates the support from the Youth Innovation Promotion Association of the Chinese Academy of Sciences (2022006).
Author information
Authors and Affiliations
Contributions
J.S., J.W. and Q.M. conceived the idea. J.S. did the device simulation, data analysis, device characterization and theoretical calculations and proposed the kinetic mechanism. J.W. and J.Z. fabricated solar cells and did the material/device characterization. F.M. did the STEM characterization and data analysis. X.X., K.Y. and L.L. participated in the device fabrication, optimization and data collection. M.J. and B.Z. participated in the device fabrication. H.W., Y.L. and D.L. participated in the experiment design and discussions. J.S. and Q.M. participated in paper writing and revising. All authors were involved in the discussions and approved the paper.
Corresponding author
Ethics declarations
Competing interests
The authors declare no competing interests.
Peer review
Peer review information
Nature Energy thanks Jonathan Staaf Scragg and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Additional information
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary information
Supplementary Information
Supplementary Note 1, Figs. 1–33 and Tables 1 and 2.
Supplementary Dataset 1
Cif files for the DFT calculations.
Source data
Source Data Fig. 1
Source data for device performance and temperature-dependent PL intensity.
Source Data Fig. 4
Unprocessed current–voltage and EQE data of the champion cell.
Rights and permissions
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
About this article
Cite this article
Shi, J., Wang, J., Meng, F. et al. Multinary alloying for facilitated cation exchange and suppressed defect formation in kesterite solar cells with above 14% certified efficiency. Nat Energy 9, 1095–1104 (2024). https://doi.org/10.1038/s41560-024-01551-5
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1038/s41560-024-01551-5