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Flexible Cu2ZnSn(S,Se)4 thin film solar cells with lithium doping via doctor blading

基于刮涂法制备锂掺杂柔性铜锌锡硫硒薄膜太阳电池

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Abstract

Lithium doping is beneficial for enhancing the performance of Cu2ZnSn(S,Se)4 (CZTSSe) thin film solar cells. However, the conventional doping strategy of spin-coating of the precursor ink containing Li source suffers from mass loss due to Li redissolution during the layer-by-layer deposition. In this study, we report an effective Li-doping strategy for preparing CZTSSe thin film on a flexible Mo foil substrate via the doctor-blading approach. In addition, we investigate the effect of Li doping on device performance. The grain size becomes larger with increasing Li-doping content, which could be attributed to the Li–Se liquid phase formation during the selenization process. Moreover, lithium can enter the CZTSSe lattice, and it tends to accumulate on the surface, passivating the defects and improving the functionality of the p–n junction. Thus, an appropriate Li-doping content enhances device performance. Furthermore, the strategy of codoping with Li and Na is preliminarily explored. Interestingly, the results reveal that introducing Na enhances the Raman signal of S vibration at 328 cm−1 compared with that of the 10%-Li sample. The efficiency of the flexible CZTSSe solar cells is further improved to 7.59%. Thus, this work provides a simple and effective strategy for Li doping via the doctor-blading method and demonstrates the interplaying mechanism between the codoped Li and Na.

摘要

锂掺杂有利于提高铜锌锡硫硒薄膜太阳电池的性能. 然而, 传统旋涂含锂前驱体溶液的掺杂策略在前驱膜的逐层沉积过程中, 由于锂的再溶解而导致大量的锂流失. 在本工作中, 我们通过刮涂法在柔性钼箔衬底上制备了铜锌锡硫硒薄膜, 实现锂的有效掺杂, 并进一步研究了锂掺杂对器件性能的影响. 随着锂掺杂含量的增加, 吸收层晶粒尺寸变大, 这可能与硒化过程中锂–硒液相的形成有关. 而且, 锂可以进入铜锌锡硫硒晶格中, 并在吸收层的表面积累, 从而钝化缺陷, 提升p–n结质量. 因此, 适量的锂掺杂可以提高器件的性能. 此外, 本工作探索了锂–钠共掺的影响. 有趣的是, 与Li-10%样品相比, 钠元素的引入增强了吸收层拉曼光谱在328 cm−1处硫的振动信号. 10%锂钠共掺可将柔性Cu2ZnSn(S,Se)4 薄膜太阳电池的效率进一步从6.62%提高到7.59%. 本工作提供了一种基于刮涂法、简单有效的锂掺杂策略, 并证明了锂–钠共掺存在相互作用机制.

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Acknowledgements

This work was supported by the Basic and Applied Basic Research Projects of Guangdong Province of China (2021A1515110520), the National Natural Science Foundation of China (62074168), China Postdoctoral Science Foundation (2021M703655), and the funding from the State Key Laboratory of Optoelectronic Materials and Technologies at Sun Yat-Sen University (OEMT-2022-ZTS-08). We also thank Prof. Zongcun Liang, Prof. Ruijiang Hong, Prof. Wan Yue, Prof. Zhengke Li, and Prof. Fang Yi for the facility and characterization support.

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Authors and Affiliations

  1. Guangzhou Key Laboratory of Flexible Electronic Materials and Wearable Devices, State Key Laboratory of Optoelectronic Materials and Technologies, Nanotechnology Research Center, School of Materials Science and Engineering, Sun Yat-Sen University, Guangzhou, 510275, China

    Han Xu  (徐菡), Sijie Ge  (葛思洁), Tao Wang  (王滔), Ening Gu  (顾鄂宁) & Xianzhong Lin  (林显忠)

  2. Key Laboratory of Polymeric Composite and Functional Materials of Ministry of Education, Sun Yat-Sen University, Guangzhou, 510275, China

    Han Xu  (徐菡), Sijie Ge  (葛思洁), Tao Wang  (王滔), Ening Gu  (顾鄂宁) & Xianzhong Lin  (林显忠)

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  1. Han Xu  (徐菡)
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  2. Sijie Ge  (葛思洁)
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Contributions

Author contributions Lin X conceived and supervised the project; Xu H conducted most of the experiments and wrote the draft of the manuscript with support from all the authors; Ge S, Wang T and Gu E participated in the discussion and analysis of the data. All the authors participate in the general discussion.

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Correspondence to Ening Gu  (顾鄂宁) or Xianzhong Lin  (林显忠).

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Conflict of interest The authors declare that they have no conflict of interest.

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Supplementary information Supporting data are available in the online version of the paper.

Han Xu received her Master’s degree in materials physics and chemistry from Sun Yat-Sen University in 2022. Currently she is pursuing her doctoral degree at the Institute of Photoelectronic Thin Film Devices and Technology, Nankai University. Her research interest includes the synthesis and characterization of energy materials and their applications in optoelectronic devices. Her current research focuses on flexible kesterite Cu2ZnSn(S,Se)4 thin-film solar cells.

Ening Gu received her PhD degree in materials science from Friedrich-Alexander-Universität Erlangen-Nürnberg in 2019 under the supervision of Prof. Christoph J. Brabec. Currently, she works as a postdoctoral fellow at the School of Materials Science and Engineering, Sun Yat-Sen University. Her research interests focus on emerging photovoltaic materials, solution-processed optoelectronic semiconductors and devices.

Xianzhong Lin received his PhD degree from the Technische Universität Berlin, Germany, in 2014. Before joining Sun Yat-Sen University as an associate professor in 2017, he worked as a postdoctoral researcher at Helmholtz-Zentrum Berlin für Materialien und Energie and Friedrich-Alexander-Universität Erlangen-Nürnberg for three years. His research focuses on highly efficient and stable thin-film solar cells based on printing approaches.

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Xu, H., Ge, S., Wang, T. et al. Flexible Cu2ZnSn(S,Se)4 thin film solar cells with lithium doping via doctor blading. Sci. China Mater. 67, 67–75 (2024). https://doi.org/10.1007/s40843-023-2670-6

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