Large metastability in Cu (In,Ga)Se<sub>2</sub> devices: The importance of buffer properties

Repins, Ingrid; Glynn, Stephen; Silverman, Timothy J.; Garris, Rebekah L.; Bowers, Karen; Stevens, Bart; Mansfield, Lorelle M.

doi:10.1002/pip.3145

Cited by 16 publications

(6 citation statements)

References 74 publications

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“…The physical properties of devices for Hall, CV and DLCP were performed under dark environment. To eliminate extra effects on samples, all samples were stored in dark and vacuum environment; , different measurements were performed with at least 3 day intervals. Therefore, photoconductivity was reproducibly obtained.…”

Section: Methodsmentioning

confidence: 99%

Efficiency Enhancement of Cu(In,Ga)(S,Se)₂ Solar Cells by Indium-Doped CdS Buffer Layers

Cheng

Cai

Huang

et al. 2020

ACS Appl. Mater. Interfaces

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Improving power conversion efficiency of photovoltaic devices has been widely investigated; however, most research studies mainly focus on the modification of the absorber layer. Here, we present an approach to enhance the efficiency of Cu(In,Ga)(S,Se)2 (CIGSSe) thin-film solar cells simply by tuning the CdS buffer layer. The CdS buffer layer was deposited by chemical bath deposition. Indium doping was done during the growth process by adding InCl3 into the growing aqueous solution. We show that the solar cell efficiency is increased by proper indium doping. Based on the characteristics of the single CdS (with or without In-doping) layer and of the CIGSSe/CdS interface, we conclude that the efficiency enhancement is attributed to the interface-defect passivation of heterojunction, which significantly improves both open circuit voltage and fill factor. The results were supported by SCAPS simulations, which suggest that our approach can also be applied to other buffer systems.

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Section: Methodsmentioning

confidence: 99%

Efficiency Enhancement of Cu(In,Ga)(S,Se)₂ Solar Cells by Indium-Doped CdS Buffer Layers

Cheng

Cai

Huang

et al. 2020

ACS Appl. Mater. Interfaces

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“…Wavelengths in the UV are not known to harm CIGS, but rather induce metastable effects depending on the absorber/buffer interface. [21][22][23][24] Additionally, the intensity of plasma radiation does barely scale with applied power, but rather with pressure. Together, this leads to the conclusion that the damage is not radiation based.…”

Section: Influence Of Sputter Parameters On Carrier Lifetimementioning

confidence: 99%

Investigation and Mitigation of Sputter Damage on Co‐Evaporated Cu(In,Ga)Se₂ Absorbers for Photovoltaic Applications

Hertwig

Nishiwaki

2022

Solar RRL

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Herein, the detrimental impact of radio frequency (RF)‐sputtering on bare Cu(In,Ga)Se2 photovoltaic absorbers in view of vacuum‐deposited buffer layers is evaluated, and the possible mitigation strategies are explored. Carrier lifetimes are measured using time‐resolved photoluminescence before and after buffer deposition and exposure to the plasma environment. When directly applied on bare Cu(In,Ga)Se2 absorbers, RF‐sputtering is severely limiting the device performance, with oxygen ions emanating from the target having a stronger effect than argon ions from the process gas. The possibilities to avoid sputter damage by atomic layer deposited Zn1−xMgxO and chemical bath deposited CdS buffer layers are shown, and the ability of the latter to restore damaged surfaces is highlighted. Absorber performance is also investigated for absorbers stored in air, N2, or ultra‐high vacuum. The reduction in carrier lifetime is reflected in the reduced open‐circuit voltage of solar cells. SCAPS simulations are used to investigate possibilities to minimize the effect of sputter damage. Finally, options on how to minimize sputter damage during buffer deposition as well as on how to modify the absorber to be less sensitive are discussed.

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“…Metastabilities have been observed in Cu(In,Ga)Se 2 solar cells early on: light soaking describes the effect that the open circuit voltage increases with illumination time [40]. There exists a variety of metastable effects, some of them are clearly related to the buffer or the buffer/absorber interface [41][42][43][44]. Here, we concentrate on metastable effects related to the Cu(In,Ga)Se 2 absorber.…”

Section: Native Defects and Metastabilitiesmentioning

confidence: 99%

Chalcopyrite solar cells —state-of-the-art and options for improvement

Siebentritt

Weiss

2022

Sci. China Phys. Mech. Astron.

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Chalcopyrite solar cells will have to play an important role to mitigate the climate crisis, because of their particularly low carbon emissions. Doping in these semiconductors is due to native defects and intentional alkali impurities. The recent progress in efficiency has been made possible by post-deposition treatments with heavy alkalis. Tail states and band gap distribution are the main limitations for the open circuit voltage in state-of-the-art chalcopyrite solar cells. Further efficiency limitations are due to the increased diode factor because of metastable defect transitions. Alloying with Ag opens new possibilities of band-edge engineering, as well as seems to improve the diode factor. In state-of-the-art cells the back contact is passivated by a Ga gradient; considerable research has been done to passivate the back contact by structured or continuous dielectric layers. A leap forward in efficiency can be expected from tandem cells. Chalcopyrite solar cells show promising potential as bottom cells as well as top cells.

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Large metastability in Cu (In,Ga)Se₂ devices: The importance of buffer properties

Cited by 16 publications

References 74 publications

Efficiency Enhancement of Cu(In,Ga)(S,Se)₂ Solar Cells by Indium-Doped CdS Buffer Layers

Efficiency Enhancement of Cu(In,Ga)(S,Se)₂ Solar Cells by Indium-Doped CdS Buffer Layers

Investigation and Mitigation of Sputter Damage on Co‐Evaporated Cu(In,Ga)Se₂ Absorbers for Photovoltaic Applications

Chalcopyrite solar cells —state-of-the-art and options for improvement

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Large metastability in Cu (In,Ga)Se2 devices: The importance of buffer properties

Cited by 16 publications

References 74 publications

Efficiency Enhancement of Cu(In,Ga)(S,Se)2 Solar Cells by Indium-Doped CdS Buffer Layers

Efficiency Enhancement of Cu(In,Ga)(S,Se)2 Solar Cells by Indium-Doped CdS Buffer Layers

Investigation and Mitigation of Sputter Damage on Co‐Evaporated Cu(In,Ga)Se2 Absorbers for Photovoltaic Applications

Chalcopyrite solar cells —state-of-the-art and options for improvement

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Product

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Large metastability in Cu (In,Ga)Se₂ devices: The importance of buffer properties

Efficiency Enhancement of Cu(In,Ga)(S,Se)₂ Solar Cells by Indium-Doped CdS Buffer Layers

Efficiency Enhancement of Cu(In,Ga)(S,Se)₂ Solar Cells by Indium-Doped CdS Buffer Layers

Investigation and Mitigation of Sputter Damage on Co‐Evaporated Cu(In,Ga)Se₂ Absorbers for Photovoltaic Applications