Na-doping-induced modification of the Cu2ZnSn(S,Se)4/CdS heterojunction towards efficient solar cells

Sun, Yali; Guo, Hongling; Qiu, Pengfei; Zhang, Shengli; Wang, Siyu; Wu, Li; Ao, Jianping; Zhang, Yi

doi:10.1016/j.jechem.2020.09.007

Cited by 46 publications

(29 citation statements)

References 44 publications

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“…The main characteristic peaks at 175, 197, and 236 cm −1 corresponding to the B‐mode, A‐mode, and E‐mode of CZTSSe are observed. [ 39,40 ] Moreover, the A‐mode of Cu 2 ZnSnS 4 shifts from 338 to 331 cm −1 as the Se content incorporated into CZTS increases. [ 41 ] In addition, a weak peak at 247 cm −1 belonging to the ZnSe phase is also observed for both samples, indicating that the surfaces of both films are Zn rich.…”

Section: Resultsmentioning

confidence: 99%

Defect Control for High‐Efficiency Cu₂ZnSn(S,Se)₄ Solar Cells by Atomic Layer Deposition of Al₂O₃ on Precursor Film

et al. 2021

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Cu2ZnSn(S,Se)4 are emerging as promising photovoltaic materials due to their outstanding photoelectrical performances, benign grain boundaries, and Earth‐abundant constituent elements. However, there are largely distributed cation‐disordering defects and defect clusters, which lead to an increase in recombination and a large open‐circuit voltage deficit and thus deteriorate device performance. Herein, defect control for a high‐efficiency Cu2ZnSn(S,Se)4 solar cell by atomic layer deposition of aluminum oxide (ALD‐Al2O3) on the precursor film is reporter. CuZn defects and Sn‐related deep defects are largely suppressed because of the decrease in Sn2+ and the increase in Sn4+ in the film by ALD‐Al2O3 on the precursor are found, and the crystallinity of absorber layer is improved from a double‐layer structure to a completely single‐layer structure. Furthermore, the carrier lifetime and recombination in the bulk and interface are significantly improved for devices with ultrathin Al2O3. Using this approach, the conversion efficiency increases from 8.8% to 11.0% and the open‐circuit voltage deficit decreases from 0.621 to 0.577 V. Herein, a deep understanding of the relationship between Al2O3 incorporation and high‐efficiency Cu2ZnSn(S,Se)4 devices and a new direction for controlling defects to further improve the performance of kesterite solar cells are provided.

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Section: Resultsmentioning

confidence: 99%

Defect Control for High‐Efficiency Cu₂ZnSn(S,Se)₄ Solar Cells by Atomic Layer Deposition of Al₂O₃ on Precursor Film

et al. 2021

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“…The higher surface-free energy indicates better wetting of hydrophilic materials; this condition is conducive to the growth of the precursor films and the reduction of stress. [30][31][32] The specific values of the grain size were discussed in detail in AFM characterization. In addition, other CZTSSe peaks were located between the peaks of the standard kesterite Cu 2 ZnSnSe 4 and Cu 2 ZnSnS 4 phases, according to JCPDS standard card CZTSe no.…”

Section: Resultsmentioning

confidence: 99%

“…When the ratios of Sn 4þ to Sn 2þ was 1:0 and 0:1, the average roughness was 91.46 and 99.26 nm. According to the literature, [30,[33][34][35][36][37] the rough CZTSSe films have a comparatively high number of defects in the heterojunction region, which acts as an interfacial recombination center. The smaller roughness indicates the better film surface quality of absorption layer, which is beneficial for the growth of the much better and more uniform CdS film with the same chemical bath deposition (CBD) process, showing superior heterojunction quality.…”

Section: Resultsmentioning

confidence: 99%

“…The smaller roughness indicates the better film surface quality of absorption layer, which is beneficial for the growth of the much better and more uniform CdS film with the same chemical bath deposition (CBD) process, showing superior heterojunction quality. [30,38,39] The interfacial defect concentration decreases, and the interface recombination has been effectively suppressed.…”

Section: Resultsmentioning

confidence: 99%

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Optimizing the Ratio of Sn⁴⁺ and Sn²⁺ in Cu₂ZnSn(S,Se)₄ Precursor Solution via Air Environment for Highly Efficient Solar Cells

Liang

Xie

et al. 2021

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The use of different Sn valence states (such as Sn4+ and Sn2+) in the Cu2ZnSn(S,Se)4 (CZTSSe) precursor solution is especially important for the quality of the subsequent growth of the CZTSSe films. The latest study has found that replacing SnCl2·2H2O with anhydrous SnCl4 can remarkably improve the performance of CZTSSe solar cells, but it needs to be operated in the glovebox. Herein, for the precursor solution, SnCl4·5H2O powder is used instead of anhydrous SnCl4 in air environment, and the proportion of Sn4+ and Sn2+ precursor solutions is further systematically studied. When the ratio of Sn4+ to Sn2+ is 1:1, a uniform, compact, and noncracking CZTSSe thin film is obtained, effectively alleviating the interface recombination and reducing the concentration of deep‐level defects. In particular, the concentration of CuZn antisite defects is decreased by an order of magnitude, and the carrier recombination and band tail effect are alleviated. When JSC is maintained, VOC and FF are considerably improved. Finally, CZTSSe thin‐film solar cells are fabricated with an efficiency of over 11%. Herein, the feasibility of controlling the ratio of Sn4+ to Sn2+ in the CZTSSe precursor solution for higher efficiency of CZTSSe thin‐film solar cells is demonstrated.

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“…Experimentally, alkali doping for kesterite has also been intensively investigated. [45,[114][115][116] Gershon et al fabricated a highly Na-containing CZTSe film by predepositing a NaF layer on Nafree substrate. The introducing of NaF shows a strong influence on the electrical properties and morphology of CZTSSe absorbers (Figure 5b-f).…”

Section: Alkali Treatments In Kesterite Solar Cellsmentioning

confidence: 99%

Kesterite Solar Cells: Insights into Current Strategies and Challenges

et al. 2021

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Earth‐abundant and environmentally benign kesterite Cu2ZnSn(S,Se)4 (CZTSSe) is a promising alternative to its cousin chalcopyrite Cu(In,Ga)(S,Se)2 (CIGS) for photovoltaic applications. However, the power conversion efficiency of CZTSSe solar cells has been stagnant at 12.6% for years, still far lower than that of CIGS (23.35%). In this report, insights into the latest cutting‐edge strategies for further advance in the performance of kesterite solar cells is provided, particularly focusing on the postdeposition thermal treatment (for bare absorber, heterojunction, and completed device), alkali doping, and bandgap grading by engineering graded cation and/or anion alloying. These strategies, which have led to the step‐change improvements in the power conversion efficiency of the counterpart CIGS solar cells, are also the most promising ones to achieve further efficiency breakthroughs for kesterite solar cells. Herein, the recent advances in kesterite solar cells along these pathways are reviewed, and more importantly, a comprehensive understanding of the underlying mechanisms is provided, and promising directions for the ongoing development of kesterite solar cells are proposed.

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Na-doping-induced modification of the Cu2ZnSn(S,Se)4/CdS heterojunction towards efficient solar cells

Cited by 46 publications

References 44 publications

Defect Control for High‐Efficiency Cu₂ZnSn(S,Se)₄ Solar Cells by Atomic Layer Deposition of Al₂O₃ on Precursor Film

Defect Control for High‐Efficiency Cu₂ZnSn(S,Se)₄ Solar Cells by Atomic Layer Deposition of Al₂O₃ on Precursor Film

Optimizing the Ratio of Sn⁴⁺ and Sn²⁺ in Cu₂ZnSn(S,Se)₄ Precursor Solution via Air Environment for Highly Efficient Solar Cells

Kesterite Solar Cells: Insights into Current Strategies and Challenges

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Na-doping-induced modification of the Cu2ZnSn(S,Se)4/CdS heterojunction towards efficient solar cells

Cited by 46 publications

References 44 publications

Defect Control for High‐Efficiency Cu2ZnSn(S,Se)4 Solar Cells by Atomic Layer Deposition of Al2O3 on Precursor Film

Defect Control for High‐Efficiency Cu2ZnSn(S,Se)4 Solar Cells by Atomic Layer Deposition of Al2O3 on Precursor Film

Optimizing the Ratio of Sn4+ and Sn2+ in Cu2ZnSn(S,Se)4 Precursor Solution via Air Environment for Highly Efficient Solar Cells

Kesterite Solar Cells: Insights into Current Strategies and Challenges

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Product

Resources

About

Defect Control for High‐Efficiency Cu₂ZnSn(S,Se)₄ Solar Cells by Atomic Layer Deposition of Al₂O₃ on Precursor Film

Defect Control for High‐Efficiency Cu₂ZnSn(S,Se)₄ Solar Cells by Atomic Layer Deposition of Al₂O₃ on Precursor Film

Optimizing the Ratio of Sn⁴⁺ and Sn²⁺ in Cu₂ZnSn(S,Se)₄ Precursor Solution via Air Environment for Highly Efficient Solar Cells