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Vol. 17 (2025)

Highest Solar-to-Hydrogen Conversion Efficiency in Cu2ZnSnS4 Photocathodes and Its Directly Unbiased Solar Seawater Splitting

https://doi.org/10.1007/s40820-025-01755-8
Muhammad Abbas
Institute of Thin Film Physics and Applications, Shenzhen Key Laboratory of Advanced Thin Films and Applications, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, State Key Laboratory of Radio Frequency Heterogeneous Integration, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, People’s Republic of China
Shuo Chen
Institute of Thin Film Physics and Applications, Shenzhen Key Laboratory of Advanced Thin Films and Applications, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, State Key Laboratory of Radio Frequency Heterogeneous Integration, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, People’s Republic of China
Zhidong Li
Institute of Thin Film Physics and Applications, Shenzhen Key Laboratory of Advanced Thin Films and Applications, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, State Key Laboratory of Radio Frequency Heterogeneous Integration, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, People’s Republic of China
Muhammad Ishaq
Institute of Thin Film Physics and Applications, Shenzhen Key Laboratory of Advanced Thin Films and Applications, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, State Key Laboratory of Radio Frequency Heterogeneous Integration, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, People’s Republic of China
Zhuanghao Zheng
Institute of Thin Film Physics and Applications, Shenzhen Key Laboratory of Advanced Thin Films and Applications, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, State Key Laboratory of Radio Frequency Heterogeneous Integration, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, People’s Republic of China
Juguang Hu
Institute of Thin Film Physics and Applications, Shenzhen Key Laboratory of Advanced Thin Films and Applications, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, State Key Laboratory of Radio Frequency Heterogeneous Integration, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, People’s Republic of China
Zhenghua Su
Institute of Thin Film Physics and Applications, Shenzhen Key Laboratory of Advanced Thin Films and Applications, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, State Key Laboratory of Radio Frequency Heterogeneous Integration, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, People’s Republic of China
Yanbo Li
Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, People’s Republic of China
Liming Ding
School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, People’s Republic of China
Guangxing Liang
Institute of Thin Film Physics and Applications, Shenzhen Key Laboratory of Advanced Thin Films and Applications, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, State Key Laboratory of Radio Frequency Heterogeneous Integration, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, People’s Republic of China

Corresponding Author: Guangxing Liang

lgx@szu.edu.cn

Nano-Micro Letters, Vol. 17 (2025), Article Number: 257

Abstract

Despite being an excellent candidate for a photocathode, Cu2ZnSnS4 (CZTS) performance is limited by suboptimal bulk and interfacial charge carrier dynamics. In this work, we introduce a facile and versatile CZTS precursor seed layer engineering technique, which significantly enhances crystal growth and mitigates detrimental defects in the post-sulfurized CZTS light-absorbing films. This effective optimization of defects and charge carrier dynamics results in a highly efficient CZTS/CdS/TiO2/Pt thin-film photocathode, achieving a record half-cell solar-to-hydrogen (HC-STH) conversion efficiency of 9.91%. Additionally, the photocathode exhibits a highest photocurrent density (Jph) of 29.44 mA cm−2 (at 0 VRHE) and favorable onset potential (Von) of 0.73 VRHE. Furthermore, our CTZS photocathode demonstrates a remarkable Jph of 16.54 mA cm−2 and HC-STH efficiency of 2.56% in natural seawater, followed by an impressive unbiased STH efficiency of 2.20% in a CZTS-BiVO4 tandem cell. The scalability of this approach is underscored by the successful fabrication of a 4 × 4 cm2 module, highlighting its significant potential for practical, unbiased in situ solar seawater splitting applications.


Highlights:
1 A novel approach, precursor seed layer engineering, is applied to prepare Cu2ZnSnS4 (CZTS) light-absorbing films using the solution-processed spin-coating method.
2 Mo/CZTS/CdS/TiO2/Pt photocathode effectively mitigates defects in CZTS light absorber and the CZTS/CdS heterojunction interface, optimizing charge carrier dynamics.
3 Record photoelectrochemical performance including half-cell solar-to-hydrogen (HC-STH) efficiency of 9.91%, photocurrent density of 29.44 mA cm−2 at 0 VRHE in 0.5 M H2SO4 electrolyte, and STH efficiency of 2.20% in CZTS-BiVO4 tandem cell in natural seawater is achieved.

Keywords

Cu2ZnSnS4 Solar-to-hydrogen conversion Charge transfer dynamics Precursor seed layer engineering Seawater splitting
Abbas, Muhammad, Shuo Chen, Zhidong Li, Muhammad Ishaq, Zhuanghao Zheng, Juguang Hu, Zhenghua Su, Yanbo Li, Liming Ding, and Guangxing Liang. 2025. “Highest Solar-to-Hydrogen Conversion Efficiency in Cu2ZnSnS4 Photocathodes and Its Directly Unbiased Solar Seawater Splitting”. Nano-Micro Letters 17 (May):257. https://doi.org/10.1007/s40820-025-01755-8.
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References
  1. T. Hisatomi, K. Domen, Reaction systems for solar hydrogen production via water splitting with particulate semiconductor photocatalysts. Nat. Catal. 2(5), 387–399 (2019). https://doi.org/10.1038/s41929-019-0242-6
  2. A. Fujishima, K. Honda, Electrochemical photolysis of water at a semiconductor electrode. Nature 238(5358), 37–38 (1972). https://doi.org/10.1038/238037a0
  3. X. Zhang, Y. Guo, C. Wang, Multi-interface engineering of nickel-based electrocatalysts for alkaline hydrogen evolution reaction. Energy Mater. 4, 400044 (2024). https://doi.org/10.20517/energymater.2023.115
  4. P. Guo, Y. Tang, J. Cheng, R. Mo, J. Luo et al., Improving Cu2ZnSnS4-based photocathodes for solar water splitting via SnO2 overlayers. ACS Energy Lett. 9(12), 6055–6063 (2024). https://doi.org/10.1021/acsenergylett.4c02686
  5. G. Liang, Z. Li, M. Ishaq, Z. Zheng, Z. Su et al., Charge separation enhancement enables record photocurrent density in Cu2ZnSn(S, Se)4 photocathodes for efficient solar hydrogen production. Adv. Energy Mater. 13(19), 2300215 (2023). https://doi.org/10.1002/aenm.202300215
  6. D. Huang, L. Li, K. Wang, Y. Li, K. Feng et al., Wittichenite semiconductor of Cu3BiS3 films for efficient hydrogen evolution from solar driven photoelectrochemical water splitting. Nat. Commun. 12, 3795 (2021). https://doi.org/10.1038/s41467-021-24060-5
  7. S. Ikeda, W. Fujita, R. Katsube, Y. Nose, H. Suzuki et al., Crystalline-face-dependent photoelectrochemical properties of single crystalline CuGaSe2 photocathodes for hydrogen evolution under sunlight radiation. Electrochim. Acta 454, 142384 (2023). https://doi.org/10.1016/j.electacta.2023.142384
  8. J. Song, B. Teymur, Y. Zhou, E. Ngaboyamahina, D.B. Mitzi, Porous Cu2BaSn(S, Se)4 film as a photocathode using non-toxic solvent and a ball-milling approach. ACS Appl. Energy Mater. 4, 81–87 (2021). https://doi.org/10.1021/acsaem.0c01892
  9. U. Chalapathi, C. Hemalatha, S. Alhammadi, G.S. Reddy, A. Divya et al., Understanding phase evolution in CuSbS2 absorbers via rapid sulfurization of Cu/Sb/Cu stacks. Phys. B Condens. Matter 690, 416241 (2024). https://doi.org/10.1016/j.physb.2024.416241
  10. W. Yang, J.H. Kim, O.S. Hutter, L.J. Phillips, J. Tan et al., Benchmark performance of low-cost Sb2Se3 photocathodes for unassisted solar overall water splitting. Nat. Commun. 11, 861 (2020). https://doi.org/10.1038/s41467-020-14704-3
  11. J.-X. Jian, L.-H. Xie, A. Mumtaz, T. Baines, J.D. Major et al., Interface-engineered Ni-coated CdTe heterojunction photocathode for enhanced photoelectrochemical hydrogen evolution. ACS Appl. Mater. Interfaces 15(17), 21057–21065 (2023). https://doi.org/10.1021/acsami.3c01476
  12. B. Koo, S. Byun, S.W. Nam, S.Y. Moon, S. Kim et al., Reduced graphene oxide as a catalyst binder: greatly enhanced photoelectrochemical stability of Cu(In, Ga)Se2 photocathode for solar water splitting. Adv. Funct. Mater. 28(16), 1705136 (2018). https://doi.org/10.1002/adfm.201705136
  13. M. Chen, Y. Liu, C. Li, A. Li, X. Chang et al., Spatial control of cocatalysts and elimination of interfacial defects towards efficient and robust CIGS photocathodes for solar water splitting. Energy Environ. Sci. 11(8), 2025–2034 (2018). https://doi.org/10.1039/c7ee03650g
  14. B. Koo, D. Kim, P. Boonmongkolras, S.R. Pae, S. Byun et al., Unassisted water splitting exceeding 9% solar-to-hydrogen conversion efficiency by Cu(In, Ga)(S, Se)2 photocathode with modified surface band structure and halide perovskite solar cell. ACS Appl. Energy Mater. 3(3), 2296–2303 (2020). https://doi.org/10.1021/acsaem.9b02387
  15. P. Zhou, I.A. Navid, Y. Ma, Y. Xiao, P. Wang et al., Solar-to-hydrogen efficiency of more than 9% in photocatalytic water splitting. Nature 613(7942), 66–70 (2023). https://doi.org/10.1038/s41586-022-05399-1
  16. S. Chamekh, N. Khemiri, M. Kanzari, Effect of annealing under different atmospheres of CZTS thin films as absorber layer for solar cell application. SN Appl. Sci. 2(9), 1507 (2020). https://doi.org/10.1007/s42452-020-03287-9
  17. R.J. Deokate, R.S. Kate, S.C. Bulakhe, Physical and optical properties of sprayed Cu2ZnSnS4 (CZTS) thin film: effect of Cu concentration. J. Mater. Sci. Mater. Electron. 30(4), 3530–3538 (2019). https://doi.org/10.1007/s10854-018-00630-0
  18. S.S. Fouad, I.M. El Radaf, P. Sharma, M.S. El-Bana, Multifunctional CZTS thin films: structural, optoelectrical, electrical and photovoltaic properties. J. Alloys Compd. 757, 124–133 (2018). https://doi.org/10.1016/j.jallcom.2018.05.033
  19. D. Yokoyama, T. Minegishi, K. Jimbo, T. Hisatomi, G. Ma et al., H2 evolution from water on modified Cu2ZnSnS4 photoelectrode under solar light. Appl. Phys. Express 3, 101202 (2010). https://doi.org/10.1143/APEX.3.101202
  20. P. Wang, T. Minegishi, G. Ma, K. Takanabe, Y. Satou et al., Photoelectrochemical conversion of toluene to methylcyclohexane as an organic hydride by Cu2ZnSnS4-based photoelectrode assemblies. J. Am. Chem. Soc. 134(5), 2469–2472 (2012). https://doi.org/10.1021/ja209869k
  21. G. Xiao, X. Ren, Y. Hu, Y. Cao, Z. Li et al., Spin-coated CZTS film with a gradient Cu-deficient interfacial layer for solar hydrogen evolution. ACS Energy Lett. 9(2), 715–726 (2024). https://doi.org/10.1021/acsenergylett.4c00013
  22. L. Li, K. Feng, D. Huang, K. Wang, Y. Li et al., Surface plasmon resonance effect of a Pt-nano-ps-modified TiO2 nanoball overlayer enables a significant enhancement in efficiency to 3.5% for a Cu2ZnSnS4-based thin film photocathode used for solar water splitting. Chem. Eng. J. 396, 125264 (2020). https://doi.org/10.1016/j.cej.2020.125264
  23. L. Li, C. Wang, K. Feng, D. Huang, K. Wang et al., Kesterite Cu2ZnSnS4 thin-film solar water-splitting photovoltaics for solar seawater desalination. Cell Rep. Phys. Sci. 2, 100468 (2021). https://doi.org/10.1016/j.xcrp.2021.100468
  24. W. Chen, A.-S. She, M.-H. Ji, H.-Y. Shi, Y. Yang et al., Optimizing charge separation and transport: enhanced photoelectrochemical water splitting in α-Fe2O3/CZTS nanorod arrays. Catalysts 14(11), 812 (2024). https://doi.org/10.3390/catal14110812
  25. Y.F. Tay, M. Zhang, S. Zhang, S. Lie, S.Y. Chiam et al., Charge transfer enhancement at the CZTS photocathode interface using ITO for efficient solar water reduction. J. Mater. Chem. A 11(48), 26543–26550 (2023). https://doi.org/10.1039/d3ta05227c
  26. D. Huang, K. Wang, L. Li, K. Feng, N. An et al., 3.17% efficient Cu2ZnSnS4–BiVO4 integrated tandem cell for standalone overall solar water splitting. Energy Environ. Sci. 14(3), 1480–1489 (2021). https://doi.org/10.1039/d0ee03892j
  27. S. Chen, X. Gong, A. Walsh, S.-H. Wei, Defect physics of the kesterite thin-film solar cell absorber Cu2ZnSnS4. Appl. Phys. Lett. 96, 021902 (2010). https://doi.org/10.1063/1.3275796
  28. M. Kumar, A. Dubey, N. Adhikari, S. Venkatesan, Q. Qiao, Strategic review of secondary phases, defects and defect-complexes in kesterite CZTS–Se solar cells. Energy Environ. Sci. 8(11), 3134–3159 (2015). https://doi.org/10.1039/c5ee02153g
  29. M.A. Olgar, A. Seyhan, A.O. Sarp, R. Zan, Impact of sulfurization parameters on properties of CZTS thin films grown using quaternary target. J. Mater. Sci. Mater. Electron. 31(22), 20620–20631 (2020). https://doi.org/10.1007/s10854-020-04582-2
  30. M.A. Olgar, A.O. Sarp, A. Seyhan, R. Zan, Impact of stacking order and annealing temperature on properties of CZTS thin films and solar cell performance. Renew. Energy 179, 1865–1874 (2021). https://doi.org/10.1016/j.renene.2021.08.023
  31. P. Zhang, Q. Yu, X. Min, L. Guo, J. Shi et al., Fabrication of Cu2ZnSn(S, Se)4 photovoltaic devices with 10% efficiency by optimizing the annealing temperature of precursor films. RSC Adv. 8, 4119–4124 (2018). https://doi.org/10.1039/C7RA13069D
  32. S. Chen, T. Liu, M. Chen, M. Ishaq, R. Tang et al., Crystal growth promotion and interface optimization enable highly efficient Sb2Se3 photocathodes for solar hydrogen evolution. Nano Energy 99, 107417 (2022). https://doi.org/10.1016/j.nanoen.2022.107417
  33. S. Islam, M. Hossain, H. Kabir, M. Rahaman, M. Bashar et al., Optical, structural and morphological properties of spin coated copper zinc tin sulfide thin films. Int. J. Thin Films Sci. Technol. 4, 155 (2015). https://doi.org/10.12785/ijtfst/040301
  34. S. Chen, Y. Chen, H.S. Aziz, H.H. Zhang, Z.L. Li et al., A Cd-free electron transport layer simultaneously enhances charge carrier separation and transfer in Sb2Se3 photocathodes for efficient solar hydrogen production Adv. Funct. Mater. 35, 2420912 (2024). https://doi.org/10.1002/adfm.202420912
  35. T. Zhou, S. Chen, J. Wang, Y. Zhang, J. Li et al., Dramatically enhanced solar-driven water splitting of BiVO4 photoanode via strengthening hole transfer and light harvesting by co-modification of CQDs and ultrathin β-FeOOH layers. Chem. Eng. J. 403, 126350 (2021). https://doi.org/10.1016/j.cej.2020.126350
  36. C. Yan, F. Liu, N. Song, B.K. Ng, J.A. Stride et al., Band alignments of different buffer layers (CdS, Zn (O, S), and In2S3) on Cu2ZnSnS4. Appl. Phys. Lett. 104, 173901 (2014). https://doi.org/10.1063/1.4873715
  37. H.-J. Chen, S.-W. Fu, S.-H. Wu, T.-C. Tsai, H.-T. Wu et al., Structural and photoelectron spectroscopic studies of band alignment at the Cu2ZnSnS4/CdS heterojunction with slight Ni doping in Cu2ZnSnS4. J. Phys. D Appl. Phys. 49, 335102 (2016). https://doi.org/10.1088/0022-3727/2F49/2F33/2F335102
  38. Y. Li, K. Wang, D. Huang, L. Li, J. Tao et al., CdxZn1-xS/Sb2Se3 thin film photocathode for efficient solar water splitting. Appl. Catal. B Environ. 286, 119872 (2021). https://doi.org/10.1016/j.apcatb.2020.119872
  39. L. Tang, M. Zhu, W. Chen, S. Tang, Y. Feng et al., Solid solution ZnW1−x MoxO4 for enhanced photocatalytic H2 evolution. New J. Chem. 44, 19796–19801 (2020). https://doi.org/10.1039/D0NJ04622A
  40. R.V. Digraskar, B.B. Mulik, P.S. Walke, A.V. Ghule, B.R. Sathe, Enhanced hydrogen evolution reactions on nanostructured Cu2ZnSnS4 (CZTS) electrocatalyst. Appl. Surf. Sci. 412, 475–481 (2017). https://doi.org/10.1016/j.apsusc.2017.03.262
  41. G. Liang, X. Chen, D. Ren, X. Jiang, R. Tang et al., Ion doping simultaneously increased the carrier density and modified the conduction type of Sb2Se3 thin films towards quasi-homojunction solar cell. J. Materiomics. 7, 1324–1334 (2021). https://doi.org/10.1016/j.jmat.2021.02.009
  42. V. Pakštas, G. Grincienė, A. Selskis, S. Balakauskas, M. Talaikis et al., Improvement of CZTSSe film quality and superstrate solar cell performance through optimized post-deposition annealing. Sci. Rep. 12, 16170 (2022). https://doi.org/10.1038/s41598-022-20670-1
  43. X. Zhao, D. Kou, W. Zhou, Z. Zhou, Y. Meng et al., Nanoscale electrical property enhancement through antimony incorporation to pave the way for the development of low-temperature processed Cu2ZnSn(S, Se)4 solar cells. J. Mater. Chem. A 7(7), 3135–3142 (2019). https://doi.org/10.1039/c8ta11783g
  44. Y. Sun, P. Qiu, W. Yu, J. Li, H. Guo et al., N-Type surface design for p-Type CZTSSe thin film to attain high efficiency. Adv. Mater. 33, 2104330 (2021). https://doi.org/10.1002/adma.202104330
  45. Z. Yu, C. Li, S. Chen, Z. Zheng, P. Fan et al., Unveiling the selenization reaction mechanisms in ambient air-processed highly efficient kesterite solar cells. Adv. Energy Mater. 13(19), 2300521 (2023). https://doi.org/10.1002/aenm.202300521
  46. R. Tang, S. Chen, Z.H. Zheng, Z.H. Su, J.T. Luo et al., Heterojunction annealing enabling record open-circuit voltage in antimony triselenide solar cells. Adv. Mater. 34(14), 2109078 (2022). https://doi.org/10.1002/adma.202109078
  47. P. Luo, T. Imran, D.L. Ren, J. Zhao, K.W. Wu et al., Electron transport layer engineering induced carrier dynamics optimization for efficient Cd-free Sb2Se3 thin-film solar cells. Small 20(4), 2306516 (2024). https://doi.org/10.1002/smll.202306516
  48. H.-S. Duan, H. Zhou, Q. Chen, P. Sun, S. Luo et al., The identification and characterization of defect states in hybrid organic–inorganic perovskite photovoltaics. Phys. Chem. Chem. Phys. 17(1), 112–116 (2015). https://doi.org/10.1039/c4cp04479g
  49. M. Igalson, A. Czudek, Electrical spectroscopy methods for the characterization of defects in thin-film compound solar cells. J. Appl. Phys. 131(24), 240901 (2022). https://doi.org/10.1063/5.0085963
  50. S. Chen, A. Walsh, X.-G. Gong, S.-H. Wei, Classification of lattice defects in the kesterite Cu2ZnSnS4 and Cu2ZnSnSe4 earth-abundant solar cell absorbers. Adv. Mater. 25(11), 1522–1539 (2013). https://doi.org/10.1002/adma.201203146
  51. S. Agrawal, D.O. De Souza, C. Balasubramanian, S. Mukherjee, Effect of secondary phases controlled by precursor composition on the efficiency of CZTS thin film solar cell. Sol. Energy Mater. Sol. Cells 267, 112719 (2024). https://doi.org/10.1016/j.solmat.2024.112719
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