Resilient and reproducible processing for CZTSe solar cells in the range of 10%

Taskesen, Teoman; Steininger, Vincent; Chen, Wenjian; Ohland, J.; Mikolajczak, Ulf; Pareek, Devendra; Parisi, J.; Gütay, Levent

doi:10.1002/pip.3063

Cited by 20 publications

(19 citation statements)

References 15 publications

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“…7,8 An appropriate conguration of alloy precursors during kesterite processing is also known to improve the thin lm homogeneity; 9,10 moreover, using this alloy structure, reproducible and resilient kesterite absorber processing with device efficiencies above 11% can be achieved. 11,12 In this study, we report the optimization of the selenium amount during the annealing process for precursor stacks with Cu-Sn alloy layers. We have discussed the crucial impact of excess Se on the material properties and ne-tuning of the Se amount for improving the opto-electronic properties of the Cu 2 ZnSnSe 4 (CZTSe) material that nally results in the enhanced performance of solar cell devices.…”

Section: Introductionmentioning

confidence: 99%

The effect of excess selenium on the opto-electronic properties of Cu₂ZnSnSe₄ prepared from Cu–Sn alloy precursors

et al. 2019

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Section: Introductionmentioning

confidence: 99%

The effect of excess selenium on the opto-electronic properties of Cu₂ZnSnSe₄ prepared from Cu–Sn alloy precursors

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“…CZT(S,Se) growth processes based on the sputtering technique can be classified depending on the target(s) type(s) and on the deposition sequence. Either pure metallic (Cu, Zn, Sn), metallic alloys (Cu-Sn, Zn-Sn) [55][56][57][58][59] or chalcogen-containing (binary chalcogenides ZnS(e), SnS(e), SnS(e) 2 or Cu x S(e)) [5,[60][61][62] targets and their combinations [36] have been used for the synthesis of kesterites as absorber layers. Concerning the deposition sequence, processes based on sequential [5,6,9,56] or co-sputtering of different targets [61,62], leading respectively to stacked-layer or homogeneously-mixed precursors, have been extensively investigated.…”

Section: Sequential Sputtering/co-sputteringmentioning

confidence: 99%

“…Besides the progresses related to improvements in solar cell technology such as optimization of new buffer [23] and passivation layers [63], the efficiency progress is also due to the elucidation and improved control of the reaction pathways during the absorber formation. It has been shown that a route involving Cu 2 SnX 3 (X=S or Se) and ZnX is preferred over reaction paths involving binary compounds (Cu 2 X, SnX 2 and ZnX) [64,36], since loss of SnS(Se) volatile species during the annealing treatment can be suppressed.…”

Section: Sequential Sputtering/co-sputteringmentioning

confidence: 99%

“…Using the sequential sputtering route, different strategies have been adopted by different groups to control the reaction mechanisms in order to minimize or avoid the loss of volatile constituents such as metallic Zn and Sn(S,Se) [6,36] and the uncontrolled formation of secondary phases.…”

Section: Sequential Sputtering/co-sputteringmentioning

confidence: 99%

“…The use of a mixed Cu-Sn target was proven to reduce the Sn loss by driving the system towards the formation of related ternary compounds Cu 2 SnX 3 (with X=S or Se), rather than binary volatile SnX phases [36] during the annealing treatment. This strategy was adopted by the EHF/LCP group from the University of Oldenburg, which recently reported a CZTSe-based device with efficiency of 11.4% [9].…”

Section: Sequential Sputtering/co-sputteringmentioning

confidence: 99%

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Physical routes for the synthesis of kesterite

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This paper provides an overview of the physical vapor technologies used to synthesize Cu 2 ZnSn(S,Se) 4 thin films as absorber layers for photovoltaic applications. Through the years, CZT(S,Se) thin films have been fabricated using sequential stacking or co-sputtering of precursors as well as using sequential or co-evaporation of elemental sources, leading to high-efficient solar cells. In addition, pulsed laser deposition of composite targets and monograin growth by the molten salt method were developed as alternative methods for kesterite layers deposition. This review presents the growing increase of the kesterite-based solar cell efficiencies achieved over the recent years. A historical description of the main issues limiting this efficiency and of the experimental pathways designed to prevent or limit these issues is provided and discussed as well. A final section is dedicated to the description of promising process steps aiming at further improvements of solar cell efficiency, such as alkali doping and bandgap grading. intensive research on Cu 2 ZnSn(S,Se) 4 (CZT(S,Se)) kesterite compounds as CRM-free absorber layers for PV applications is essential. This article aims at establishing a complete overview of the physical routes used for the synthesis of kesterite thin films as absorber layers in solar cells. The following sections are devoted to that objective and will take on the main issues which have been raised so far as well as how the processes have evolved through the years to meet the requirements of the market. Some major advancements in terms of deposition or post-deposition treatments are introduced. Advantages and drawbacks of each of the physical methods presented in this review are described in detail and compared to other physical or chemical synthesis routes. Physical routes: status overviewWe performed an extensive identification of the common processes and methods used for the synthesis of kesterite thin films or for the design of solar cell devices. In order to avoid unnecessary repetitions along this paper, this section first explains these well-known and commonly used experimental processes and methods. Historically, based on the similarities between kesterite and chalcopyrite compounds, the standard device structure adopted for Cu(In,Ga)(S,Se) 2 (CIGSSe) was directly extended to CZTSSe, by simply replacing the CIGSSe absorber layer with a p-type CZTSSe thin film. CZTSSe solar cells are then typically produced using a soda-lime glass (SLG) substrate coated with a sputtered Mo layer acting as rear metallic contact. Typical sputter-deposited Mo layer thickness is around 500 nm up to 1 μm [12]. The kesterite absorber is then deposited onto the Mo layer.The fabrication of this absorber consists in the deposition of a precursor layer via a physical or a chemical route, which is then annealed in a reactive atmosphere containing either S (sulfurization) or Se (selenization). As a common result of the reactive annealing, a thin Mo(S,Se) 2 layer is naturally formed at the CZTSSe/Mo interface, betw...

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Defect Control for 12.5% Efficiency Cu₂ZnSnSe₄ Kesterite Thin‐Film Solar Cells by Engineering of Local Chemical Environment

et al. 2020

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over 30% detailed balance limiting efficiency, as well as to its earth-abundant and environment-benign constituents. [1-3] The increase in power conversion efficiency to a record of 12.6% in the last decade has demonstrated the huge potential of these materials. [4,5] However, as one of the most complicated compound semiconductors, kesterite has much more intricate defect chemistry than its counterparts, Cu(In,Ga)Se 2 (CIGS) and CdTe, [6-8] making the control of intrinsic defects a major challenge. Deep intrinsic defects like Sn Zn antisites and related [Cu Zn +Sn Zn ] clusters act as deep recombination centers, leading to the short carrier lifetime. [7,9,10] Additionally, the large population of defect clusters like [2Cu Zn +Sn Zn ] introduces considerable potential (i.e., band or electrostatic) fluctuation. [11] Consequently, the performance of CZTSSe solar cells are currently stagnated by the large open-circuit voltage (V OC) deficit. [12,13] To address the detrimental intrinsic defects and defect clusters in CZTSSe absorber, multiple strategies have been employed. As suggested by the first-principle calculations, the formation energy of intrinsic defects and Kesterite-based Cu 2 ZnSn(S,Se) 4 semiconductors are emerging as promising materials for low-cost, environment-benign, and high-efficiency thin-film photo voltaics. However, the current state-of-the-art Cu 2 ZnSn(S,Se) 4 devices suffer from cation-disordering defects and defect clusters, which generally result in severe potential fluctuation, low minority carrier lifetime, and ultimately unsatisfactory performance. Herein, critical growth conditions are reported for obtaining high-quality Cu 2 ZnSnSe 4 absorber layers with the formation of detrimental intrinsic defects largely suppressed. By controlling the oxidation states of cations and modifying the local chemical composition, the local chemical environment is essentially modified during the synthesis of kesterite phase, thereby effectively suppressing detrimental intrinsic defects and activating desirable shallow acceptor Cu vacancies. Consequently, a confirmed 12.5% efficiency is demonstrated with a high V OC of 491 mV, which is the new record efficiency of pure-selenide Cu 2 ZnSnSe 4 cells with lowest V OC deficit in the kesterite family by E g /q-Voc. These encouraging results demonstrate an essential route to overcome the long-standing challenge of defect control in kesterite semiconductors, which may also be generally applicable to other multinary compound semiconductors.

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Resilient and reproducible processing for CZTSe solar cells in the range of 10%

Cited by 20 publications

References 15 publications

The effect of excess selenium on the opto-electronic properties of Cu₂ZnSnSe₄ prepared from Cu–Sn alloy precursors

The effect of excess selenium on the opto-electronic properties of Cu₂ZnSnSe₄ prepared from Cu–Sn alloy precursors

Physical routes for the synthesis of kesterite

Defect Control for 12.5% Efficiency Cu₂ZnSnSe₄ Kesterite Thin‐Film Solar Cells by Engineering of Local Chemical Environment

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Resilient and reproducible processing for CZTSe solar cells in the range of 10%

Cited by 20 publications

References 15 publications

The effect of excess selenium on the opto-electronic properties of Cu2ZnSnSe4 prepared from Cu–Sn alloy precursors

The effect of excess selenium on the opto-electronic properties of Cu2ZnSnSe4 prepared from Cu–Sn alloy precursors

Physical routes for the synthesis of kesterite

Defect Control for 12.5% Efficiency Cu2ZnSnSe4 Kesterite Thin‐Film Solar Cells by Engineering of Local Chemical Environment

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Product

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The effect of excess selenium on the opto-electronic properties of Cu₂ZnSnSe₄ prepared from Cu–Sn alloy precursors

The effect of excess selenium on the opto-electronic properties of Cu₂ZnSnSe₄ prepared from Cu–Sn alloy precursors

Defect Control for 12.5% Efficiency Cu₂ZnSnSe₄ Kesterite Thin‐Film Solar Cells by Engineering of Local Chemical Environment