Restraining the Band Fluctuation of CBD‐Zn(O,S) Layer: Modifying the Hetero‐Junction Interface for High Performance Cu<sub>2</sub>ZnSnSe<sub>4</sub> Solar Cells With Cd‐Free Buffer Layer

Li, Jianjun; Liu, Xiaoru; Liu, Wei; Wu, Li; Ge, Binghui; Lin, Shuping; Gao, Shoushuai; Zhou, Zhiqiang; Liu, Fangfang; Sun, Yun; Ao, Jianping; Zhu, Hongbing; Mai, Yaohua; Zhang, Yi

doi:10.1002/solr.201700075

Cited by 37 publications

(41 citation statements)

References 30 publications

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“…A few ternary materials have shown potential as alternative buffer candidate material for kesterite-based TFSCs. They have the advantage of having (optoelectronic) properties that can easily be tuned by controlling their stoichiometry [156][157][158][159][160][161]. For Zn(O, S) buffer layers prepared by ALD, e.g.…”

Section: Zns-based Buffer Layersmentioning

confidence: 99%

Back and front contacts in kesterite solar cells: state-of-the-art and open questions

et al. 2019

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We review the present state-of-the-art within back and front contacts in kesterite thin film solar cells, as well as the current challenges. At the back contact, molybdenum (Mo) is generally used, and thick Mo(S, Se) 2 films of up to several hundred nanometers are seen in record devices, in particular for selenium-rich kesterite. The electrical properties of Mo(S, Se) 2 can vary strongly depending on orientation and indiffusion of elements from the device stack, and there are indications that the back contact properties are less ideal in the sulfide as compared to the selenide case. However, the electronic interface structure of this contact is generally not well-studied and thus poorly understood, and more measurements are needed for a conclusive statement. Transparent back contacts is a relatively new topic attracting attention as crucial component in bifacial and multijunction solar cells. Front illuminated efficiencies of up to 6% have so far been achieved by adding interlayers that are not always fully transparent. For the front contact, a favorable energy level alignment at the kesterite/CdS interface can be confirmed for kesterite absorbers with an intermediate [S]/([S]+[Se]) composition. This agrees with the fact that kesterite absorbers of this composition reach highest efficiencies when CdS buffer layers are employed, while alternative buffer materials with larger band gap, such as Cd 1−x Zn x S or Zn 1−x Sn x O y , result in higher efficiencies than devices with CdS buffers when sulfurrich kesterite absorbers are used. Etching of the kesterite absorber surface, and annealing in air or inert atmosphere before or after buffer layer deposition, has shown strong impact on device performance. Heterojunction annealing to promote interdiffusion was used for the highest performing sulfide kesterite device and air-annealing was reported important for selenium-rich record solar cells. Cu 2 ZnSnS 4 (CZTS) absorbers for solar cell applications was first reported by Ito and Nakazawa [1]. Early results on CZTS device performance were reported by Friedlmeier et al [2], Seol et al [3], and Katagiri et al [4]. Later a group at IBM reached record performances with power conversion efficiencies (PCEs) above 10% for CZTSSe devices in 2010 [5] and the current record PCE of 12.6% in 2013 [6]. In 2018, researchers from DGIST reached the same performance, 12.6%, but for a larger device area [7]. The device structure used for kesterite solar cells was originally copied from that of Cu(In, Ga)Se 2 , (CIGSe) TFSCs, and is formed by sequential deposition, upon a soda lime glass substrate, of a Mo back contact, the absorber, a CdS buffer layer, and a ZnO/ZnO:Al bi-layer window (i.e. transparent top contact). This structure, schematically shown for CZTSSe in figure 1, is not necessarily ideal for kesterite solar cells, and extensive work has been invested into studies of alternative backand front contacts and related deposition processes. In this paper, the state-of-the-art and current open questions related to the back and front c...

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Section: Zns-based Buffer Layersmentioning

confidence: 99%

Back and front contacts in kesterite solar cells: state-of-the-art and open questions

et al. 2019

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“…Part of this high RS can also be linked to a barrier at heterojunction due to the presence of a ZnS(e) phase at the surface of the absorber 61,69 or to the CBO with the buffer layer 56 . However, state-of-the-art solar cells with ZnS(O,OH) and ZnSnO buffer layers show similar FF as cells with reference CdS buffer layers [28][29] . It is still not clear whether the presence of voids at the back interface can impact the RS or not 50,70 .…”

Section: Mapping Of Fundamental Failures In Cd-free Kesterite Solar Cmentioning

confidence: 99%

“…For instance CdS is not suitable at high S content in the absorber because of a negative CBO ("cliff" alignment) 12,27 . As far as Cd&CRM-free buffer layers are concerned: CBO with ZnO (-0.1 eV) can lead to low VOC 56 , ZnSnO has a suitable CBO with CZTSSe for various S content in absorber [27][28] and if CBO with ZnS(O,OH) can be correctly adjusted 57 , inhomogeneity in this buffer layer can drastically reduce VOC 29 . Insufficient buffer coverage can also lead to decreased VOC 58 .…”

Section: Mapping Of Fundamental Failures In Cd-free Kesterite Solar Cmentioning

confidence: 99%

“…Only two candidates emerge as possible candidate to be integrated in kesterite solar cells: ZnS(O,OH) 27,28 and ZnSnO 8,29 . Other possibilities such as ZnMgO already used in chalcopyrite solar cells have not been successfully tested so far.…”

Section: Mapping Of Fundamental Failures In Cd-free Kesterite Solar Cmentioning

confidence: 99%

“…12 . PV data and related bandgaps from References [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] . Bandgaps are extracted from EQE spectra.…”

Section: Mapping Of Fundamental Failures In Cd-free Kesterite Solar Cmentioning

confidence: 99%

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Analysis of Failure Modes in Kesterite Solar Cells

Grenet

Suzon

Emieux

et al. 2018

ACS Appl. Energy Mater.

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An intense research activity has been carried out in the past few years to improve efficiencies and understand limitations in kesterite based solar cells. Despite notable efforts to determine and list the different failure modes affecting the photovoltaic properties of these devices, very few works try to quantify and classify the effect of these failure modes. In this study, an exhaustive literature review has first been conducted to determine the different causes leading to limited efficiencies in kesterite devices with an additional focus on cadmium free and critical raw material free devices. Second, an original approach has been employed to quantify the impact of these failure modes on solar cells with the evaluation of feedbacks from 18 scientific experts working on kesterite technology. The result of this survey is analyzed, which allow to determine what should be the research priority for the community to improve efficiencies and drive kesterite technology to the market.

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Gradient Conduction Band Energy Engineering Driven High‐Efficiency Solution‐Processed Cu₂ZnSn(S,Se)₄/Zn_xCd_1–x S Solar Cells

Gao

Cui

et al. 2022

Adv Funct Materials

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The photovoltaic performance of the environmentally friendly Cu 2 ZnSn(S,Se) 4 (CZTSSe) solar cells is lower than its predecessor Cu(In,Ga)Se 2 solar cells. Severe carrier recombination at theCZTSSe/CdS interface is one major reason that results in a large open-circuit voltage loss. Doping zinc into CdS is a feasible strategy to modifying the CdS buffer layer film, but the present methods are not satisfactory. In this study, novel zinc incorporation strategy is developed to deposit a gradient composition ternary Zn x Cd 1-x S buffer layer for optimizing the heterojunction interface. The application of gradient composition Zn x Cd 1-x S buffer layer constructs a gradient conduction band energy configuration in the CZTSSe/buffer layer interface, which highly reduces the interface recombination. The suppressed interface recombination contributes to the enhanced open circuit voltage and device performance. Consequently, the CZTSSe solar cell based on gradient composition Zn x Cd 1-x S buffer layers achieves champion efficiency of 12.35% with V OC of 504.81 mV, J SC of 36.90 mA cm −2 , and FF of 66.28%. It is worth noting that flammable and the toxic hydrazine solvent are replaced by the safe and low-toxic 2-methoxyethanol, making it more promising for the future commercialization of CZTSSe solar cells.

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Restraining the Band Fluctuation of CBD‐Zn(O,S) Layer: Modifying the Hetero‐Junction Interface for High Performance Cu₂ZnSnSe₄ Solar Cells With Cd‐Free Buffer Layer

Cited by 37 publications

References 30 publications

Back and front contacts in kesterite solar cells: state-of-the-art and open questions

Back and front contacts in kesterite solar cells: state-of-the-art and open questions

Analysis of Failure Modes in Kesterite Solar Cells

Gradient Conduction Band Energy Engineering Driven High‐Efficiency Solution‐Processed Cu₂ZnSn(S,Se)₄/Zn_xCd_1–x S Solar Cells

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Restraining the Band Fluctuation of CBD‐Zn(O,S) Layer: Modifying the Hetero‐Junction Interface for High Performance Cu2ZnSnSe4 Solar Cells With Cd‐Free Buffer Layer

Cited by 37 publications

References 30 publications

Back and front contacts in kesterite solar cells: state-of-the-art and open questions

Back and front contacts in kesterite solar cells: state-of-the-art and open questions

Analysis of Failure Modes in Kesterite Solar Cells

Gradient Conduction Band Energy Engineering Driven High‐Efficiency Solution‐Processed Cu2ZnSn(S,Se)4/ZnxCd1–x S Solar Cells

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Product

Resources

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Restraining the Band Fluctuation of CBD‐Zn(O,S) Layer: Modifying the Hetero‐Junction Interface for High Performance Cu₂ZnSnSe₄ Solar Cells With Cd‐Free Buffer Layer

Gradient Conduction Band Energy Engineering Driven High‐Efficiency Solution‐Processed Cu₂ZnSn(S,Se)₄/Zn_xCd_1–x S Solar Cells