Efficiency enhancement of CZTSe solar cells based on <i>in situ</i> K-doped precursor

Tao, Shengye; Dong, Liangzheng; Han, Junsu; Wei, Jinquan; Gong, Qianming; Zhao, Ming; Zhuang, Daming

doi:10.1039/d2ta09916k

Cited by 11 publications

(5 citation statements)

References 66 publications

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“…[34,60] The decrease in the density of Sn-related deep defect states may be due to the existence of element K in the absorber layer of the K 2 S device which enhances the element diffusion rate, allowing a larger fraction of the absorber to participate in the evaporation and inclusion during selenization, stabilizing the Sn content. [52] This demonstrates the necessity of selecting K 2 S material for CZTSSe, where the presence of K 2 S is able to passivate deep energy level defects, thus reducing the defect problems that may result from the increased S content. Further calculations of 𝜎×N T to evaluate the trap lifetime are shown in Figure 7j.…”

Section: Resultsmentioning

confidence: 99%

“…This PL shows that K 2 S can effectively passivate the acceptor defect (V Sn ), and it has been demonstrated that K is able to reduce Sn-related defects by promoting elemental diffusion to stabilize the Sn content. [52] Therefore, the supply of K 2 S modified the defect chemistry of CZTSSe by reducing the transition path passing through the defects and passivating the nonradiative defects in CZTSSe. In multi-crystalline CIGS and CZTSSe materials, potential fluctuation usually can act as traps for carriers to hinder carrier transport and diffusion.…”

Section: Resultsmentioning

confidence: 99%

“…Normally CZTSSe devices with high S content exhibit higher bulk defect density while K 2 S device with higher sulfur content but lower bulk defect density is attributed to the existence of alkali metal K which plays a major role in passivating the defects. [34,52] The minority carrier diffusion length (L d ) is one of the important parameters affecting the collection efficiency, biasdependent EQE (Figure S13, Supporting Information), reflectivity (Figure S14, Supporting Information) and C-V measurements (Figure S15, Supporting Information) were performed to investigate the L d of REF and K 2 S device. [55] The REF device has a strong W d dependence (large slope) and the L d value obtained is 0.77 μm.…”

Section: Resultsmentioning

confidence: 99%

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Controllable Double Gradient Bandgap Strategy Enables High Efficiency Solution‐Processed Kesterite Solar Cells

Zhao,

Chen,

Ishaq

et al. 2023

Adv Funct Materials

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The double gradient bandgap absorber has the potential to enhance carrier collection, improve light collection efficiency, and make the performance of solar cells more competitive. However, achieving the double gradient bandgap structure is challenging due to the comparable diffusion rates of cations during high‐temperature selenization in kesterite Cu2ZnSn(S,Se)4 (CZTSSe) films. Here, it has successfully achieved a double gradient bandgap in the CZTSSe absorber by spin‐coating the K2S solution during the preparation process of the precursor film. The K2S insertion serves as an additional S source for the absorber, and the high‐affinity energy of K‐Se causes the position of the spin‐coated K2S solution locally Se‐rich and S‐poor. More importantly, the position of the bandgap minimum (notch) and the depth of the notch can be controlled by varying the concentration of K2S solution and its deposition stage, thereby avoiding the electronic potential barrier produced by an inadvertent notch position and depth. In addition, the K─Se liquid phase expedites the selenization process to the elimination of the fine grain layer. The champion CZTSSe device achieved an efficiency of 13.70%, indicating the potential of double gradient bandgap engineering for the future development of high‐efficiency kesterite solar cells.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Controllable Double Gradient Bandgap Strategy Enables High Efficiency Solution‐Processed Kesterite Solar Cells

Zhao,

Chen,

Ishaq

et al. 2023

Adv Funct Materials

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“…The details of fabrication of CZTSSe layer can be found in other studies. [ 35,36 ] 600 nm‐thick ZnO:Al(AZO) film was prepared by sputtering ZnO:Al (Al 2 O 3 : 2 wt%k ZnO:Al(AZO) film was substrate temperature of 200 °C. CdS layer was obtained by chemical bath deposition which utilized cadmium surface as the source of Cd, thiourea as the source of S, and ammonia to adjust the pH value of the solution.…”

Section: Methodsmentioning

confidence: 99%

Energy Band Alignment at p–n Heterojunction Interface in CZTSSe Solar Cells with Novel ZnMgO Buffer Layer

Wang,

Tong,

Tao

et al. 2023

Solar RRL

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By substituting Zn1‐xMgxO (ZMO) for the conventional CdS buffer layer, the CZTSSe solar cells with the efficiency of 11.2% was obtained in the work, which could be attributed to the conduction band regulation in the heterojunction. An appropriate conduction band offset (CBO) value can effectively reduce non‐radiative recombination loss of charge carriers at the interface, thereby improving the open‐circuit voltage (Voc). In this study, ZMO buffer layer with the optical bandgap (Eg) ranging from 3.34 eV to 3.90 eV was applied to enhance the CBO in the heterojunction from 0.14 eV to 0.72 eV. The ZMO‐buffered solar cells exhibit higher Voc and short current density (Jsc) compared to CdS‐buffered cells. The optimal efficiency of 11.2% was obtained in CZTSSe solar cell with the CBO of 0.27eV, Jsc of 39.0 mA/cm², fill factor (FF) of 69.6%, and Voc of 412 mV.This article is protected by copyright. All rights reserved.

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“…The substrate may have controlled movement for uniform film deposition (Figure 4). The deposition of CZT(S/Se) films by evaporation can be achieved through two different approaches: single-step deposition [30,31], where all the precursors are simultaneously deposited and then followed by sulfurization, and sequential two-step deposition using different metallic or binary precursors, in different combinations and sequences, such as Cu/Sn/Zn/Cu, Cu/Sn/Cu/Zn [32], Cu-ZnS-Sn [33] or CuSn/Zn/Se/CuSn/Se [34], followed by annealing with a sulfur or selenium source.…”

Section: Evaporationmentioning

confidence: 99%

Recent Progress and Challenges in Controlling Secondary Phases in Kesterite CZT(S/Se) Thin Films: A Critical Review

Zaki,

Velea

2024

Energies

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Kesterite-based copper zinc tin sulfide (CZTS) and copper zinc tin selenide (CZTSe) thin films have attracted considerable attention as promising materials for sustainable and cost-effective thin-film solar cells. However, the successful integration of these materials into photovoltaic devices is hindered by the coexistence of secondary phases, which can significantly affect device performance and stability. This review article provides a comprehensive overview of recent progress and challenges in controlling secondary phases in kesterite CZTS and CZTSe thin films. Drawing from relevant studies, we discuss state-of-the-art strategies and techniques employed to mitigate the formation of secondary phases. These include a range of deposition methods, such as electrodeposition, sol-gel, spray pyrolysis, evaporation, pulsed laser deposition, and sputtering, each presenting distinct benefits in enhancing phase purity. This study highlights the importance of employing various characterization techniques, such as X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy, for the precise identification of secondary phases in CZTS and CZTSe thin films. Furthermore, the review discusses innovative strategies and techniques aimed at mitigating the occurrence of secondary phases, including process optimization, compositional tuning, and post-deposition treatments. These approaches offer promising avenues for enhancing the purity and performance of kesterite-based thin-film solar cells. Challenges and open questions in this field are addressed, and potential future research directions are proposed. By comprehensively analyzing recent advancements, this review contributes to a deeper understanding of secondary phase-related issues in kesterite CZT(S/Se) thin films, paving the way for enhanced performance and commercial viability of thin-film solar cell technologies.

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Efficiency enhancement of CZTSe solar cells based on in situ K-doped precursor

Abstract: An in-situ potassium (K)-doped copper–zinc–tin–sulfide (CZTS) precursor is prepared and annealed through selenization. After comprehensive optimization of the annealing, a cell with an efficiency of up to 12.62% is obtained,...

Cited by 11 publications

References 66 publications

Controllable Double Gradient Bandgap Strategy Enables High Efficiency Solution‐Processed Kesterite Solar Cells

Controllable Double Gradient Bandgap Strategy Enables High Efficiency Solution‐Processed Kesterite Solar Cells

Energy Band Alignment at p–n Heterojunction Interface in CZTSSe Solar Cells with Novel ZnMgO Buffer Layer

Recent Progress and Challenges in Controlling Secondary Phases in Kesterite CZT(S/Se) Thin Films: A Critical Review

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