Cd and Impurity Redistribution at the CdS/CIGS Interface After Annealing of CIGS-Based Solar Cells Resolved by Atom Probe Tomography

Koprek, Anna; Cojocaru‐Mirédin, Oana; Wuerz, Roland; Freysoldt, Christoph; Gault, Baptiste; Raabe, Dierk

doi:10.1109/jphotov.2016.2629841

Cited by 21 publications

(9 citation statements)

References 52 publications

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“…After annealing, no traces of Na were found in the bulk and interface region of CIGSe and In 2 S 3 layers, however a small amount (0.2 at.%) Na was found segregated at the In 2 S 3 / CIGSe interface for another region of the same sample (see Figure S3). The presence of Na close to the CIGSe surface has been previously reported by our group 41,42 suggesting the diffusion of Na from grain boundaries to the buffer/absorber interface. The present work agrees with the work from our group which suggests that the presence of Na at the interface does not depend on the annealing temperature but rather on the vicinity of the interface to a Na-rich CIGS grain boundary.…”

Section: Compositional Analysissupporting

confidence: 76%

Sputtering as a viable route for In₂S₃ buffer layer deposition in high efficiency Cu(In,Ga)Se₂ solar cells

Soni

Raghuwanshi

Wuerz

et al. 2019

Energy Science & Engineering

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Alternative buffer layers in CIGSe are deposited mainly using chemical bath deposition because of its benefits like simplicity, good film quality and surface/step coverage. All the layers in CIGSe cell stack such as back contact, absorber and window layers are deposited by vacuum-deposition methods such as coevaporation, sputtering, and sometimes thermal evaporation, except for the buffer layer. Therefore, in the present work we demonstrate the feasibility to deposit In 2 S 3 by RF magnetron sputtering reaching cell efficiencies of 13.6%, which is the highest value available for sputtered In 2 S 3 in literature to date. Absorber surface damage and nonuniform buffer layer thickness are the primary limitations when using sputtering, and hence need to be eliminated for reaching reasonable cell efficiencies. We studied the extent of sputter induced damage on CIGSe absorber as well as the sputtering-and annealing-induced intermixing phenomenon at the In 2 S 3 /Cu(In,Ga)Se 2 interface at the subnanometer level using atom probe tomography. We have also shown that a post deposition annealing not only significantly improves the crystallinity of In 2 S 3 , but also recovers the surface damage caused by sputter-induced intermixing resulting in an improved p-n Junction quality (as shown by the electron beam induced current investigations), and substantially improves cell efficiency. The present work opens a new way for designing efficient and industry-compatible CIGSe cells using sputter-deposited Cdfree buffer layers. Moreover, this work clearly demonstrates that this novel and fully vacuum-deposited CIGSe cell meets the standard requirements, in terms of chemistry, structure, and electrical performance of a working cell for the PV industry.

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Section: Compositional Analysissupporting

confidence: 76%

Sputtering as a viable route for In₂S₃ buffer layer deposition in high efficiency Cu(In,Ga)Se₂ solar cells

Soni

Raghuwanshi

Wuerz

et al. 2019

Energy Science & Engineering

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“…Because a copper sample holder was used here, the Cu signal is overestimated in both scans as well. The high Cu content inside the CdS buffer layer has been observed in many publications before, when FIB‐prepared samples are analyzed by TEM or atom probe tomography (APT) . It is suggested here, that this is likely an artifact of FIB preparation, because the GDOES measurements on the same samples showed no Cu inside the CdS layer.…”

Section: Discussion On the Impact Of Thermal Stress On Samples With (supporting

confidence: 56%

Effect of KF absorber treatment on the functionality of different transparent conductive oxide layers in CIGSe solar cells

Keller

Chalvet

Joel

et al. 2017

Progress in Photovoltaics

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“…They found that excess Cd and Zn diffuse into the CIGSe absorber layer leading to degradation of the device performance 9 . Similar observations were confirmed by other groups 10–12 . They have however not reported the effect of Na on the cell degradation.…”

Section: Introductionsupporting

confidence: 64%

Decay mechanisms in CdS‐buffered Cu(In,Ga)Se₂ thin‐film solar cells after exposure to thermal stress: Understanding the role of Na

Yetkin

Kodalle

Bertram

et al. 2021

Progress in Photovoltaics

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Due to their tunable bandgap energy, Cu(In,Ga)Se2 (CIGSe) thin‐film solar cells are an attractive option for use as bottom devices in tandem configurations. In monolithic tandem devices, the thermal stability of the bottom device is paramount for reliable application. Ideally, it will permit the processing of a top device at the required optimum process temperature. Here, we investigate the degradation behavior of chemical bath deposited (CBD) CdS‐buffered CIGSe thin‐film solar cells with and without Na incorporation under thermal stress in ambient air and vacuum with the aim to gain a more detailed understanding of their degradation mechanisms. For the devices studied, we observe severe degradation after annealing at 300°C independent of the atmosphere. The electrical and compositional properties of the samples before and after a defined application of thermal stress are studied. In good agreement with literature reports, we find pronounced Cd diffusion into the CIGS absorber layer. In addition, for Na‐containing samples, the observed degradation can be mainly explained by the formation of Na‐induced acceptor states in the TCO front contact and a back contact barrier formation due to the out‐diffusion of Na. Supported by numerical device simulation using SCAPS‐1D, various possible degradation models are discussed and correlated with our findings.

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Cd and Impurity Redistribution at the CdS/CIGS Interface After Annealing of CIGS-Based Solar Cells Resolved by Atom Probe Tomography

Cited by 21 publications

References 52 publications

Sputtering as a viable route for In₂S₃ buffer layer deposition in high efficiency Cu(In,Ga)Se₂ solar cells

Sputtering as a viable route for In₂S₃ buffer layer deposition in high efficiency Cu(In,Ga)Se₂ solar cells

Effect of KF absorber treatment on the functionality of different transparent conductive oxide layers in CIGSe solar cells

Decay mechanisms in CdS‐buffered Cu(In,Ga)Se₂ thin‐film solar cells after exposure to thermal stress: Understanding the role of Na

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Cd and Impurity Redistribution at the CdS/CIGS Interface After Annealing of CIGS-Based Solar Cells Resolved by Atom Probe Tomography

Cited by 21 publications

References 52 publications

Sputtering as a viable route for In2S3 buffer layer deposition in high efficiency Cu(In,Ga)Se2 solar cells

Sputtering as a viable route for In2S3 buffer layer deposition in high efficiency Cu(In,Ga)Se2 solar cells

Effect of KF absorber treatment on the functionality of different transparent conductive oxide layers in CIGSe solar cells

Decay mechanisms in CdS‐buffered Cu(In,Ga)Se2 thin‐film solar cells after exposure to thermal stress: Understanding the role of Na

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Product

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Sputtering as a viable route for In₂S₃ buffer layer deposition in high efficiency Cu(In,Ga)Se₂ solar cells

Sputtering as a viable route for In₂S₃ buffer layer deposition in high efficiency Cu(In,Ga)Se₂ solar cells

Decay mechanisms in CdS‐buffered Cu(In,Ga)Se₂ thin‐film solar cells after exposure to thermal stress: Understanding the role of Na