Relationship between absorber layer defect density and performance of a‐Si:H and µc‐Si:H solar cells studied over a wide range of defect densities generated by 2 MeV electron bombardment

Astakhov, Oleksandr; Smirnov, Vladimir; Carius, R.; Pieters, Bart E.; Petrusenko, Yuri; Borysenko, Valeriy; Finger, F.

doi:10.1016/j.solmat.2013.12.024

“…Moreover, when the density of the surface defects increases from 10 13 cm -2 to 5 × 10 16 cm -2 , the short-circuit current density decreases drastically from 16.43 mA/cm 2 to 11.47 mA/cm 2 (Figure 6(a)). This decrease is due to increased recombination centers at the interface buffer layer/i-(a-Si:H), favouring electron traps but also the loss by optical absorption of the incident light [33].…”

Section: Resultsmentioning

confidence: 99%

Numerical Design of Ultrathin Hydrogenated Amorphous Silicon-Based Solar Cell

Abega

¹

,

Ngoupo

²

,

Ndjaka

³

2021

International Journal of Photoenergy

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Numerical modelling is used to confirm experimental and theoretical work. The aim of this work is to present how to simulate ultrathin hydrogenated amorphous silicon- (a-Si:H-) based solar cells with a ITO BRL in their architectures. The results obtained in this study come from SCAPS-1D software. In the first step, the comparison between the J-V characteristics of simulation and experiment of the ultrathin a-Si:H-based solar cell is in agreement. Secondly, to explore the impact of certain properties of the solar cell, investigations focus on the study of the influence of the intrinsic layer and the buffer layer/absorber interface on the electrical parameters ( J SC , V OC , FF, and η ). The increase of the intrinsic layer thickness improves performance, while the bulk defect density of the intrinsic layer and the surface defect density of the buffer layer/ i -(a-Si:H) interface, respectively, in the ranges [109 cm-3, 1015 cm-3] and [1010 cm-2, 5 × 10 13 cm-2], do not affect the performance of the ultrathin a-Si:H-based solar cell. Analysis also shows that with approximately 1 μm thickness of the intrinsic layer, the optimum conversion efficiency is 12.71% ( J SC = 18.95 mA · c m − 2 , V OC = 0.973 V , and FF = 68.95 % ). This work presents a contribution to improving the performance of a-Si-based solar cells.

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“…The plasma might damage the PET substrate , dissolving contaminating atoms like carbon or oxygen from the substrate, which are subsequently incorporated into the silicon layers. Incorporation of these atoms may cause additional electronic defects, reducing the photoelectronic quality of the silicon layer, which consequently would impede the charge carrier collection efficiency . Furthermore, PET is known to be permeable to water and oxygen , so without a diffusion barrier such as ZnSnO x , impurities may also enter the silicon layers though the PET substrate.…”

Section: Discussionmentioning

confidence: 99%

Influence of ZnSnO _x barrier layer on the texturing of ZnO:Al layers for light management in flexible thin-film silicon solar cells

Wilken

¹

,

Finger

²

,

Smirnov

³

2017

Phys. Status Solidi A

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Transparent polymer films such as polyethylene terephthalate (PET) present a cost efficient substrate material for flexible solar cells. In addition to certain process temperature limitations, these materials are permeable to moisture and/or oxygen, and additional barrier layers are required to prevent the diffusion of contaminating atoms into the photovoltaic device. In this study, the influence of a ZnSnOx barrier layer deposited on PET substrates on the properties of the subsequently grown low temperature (<140 °C) aluminum‐doped zinc oxide (ZnO:Al) layers is examined. We investigate the electrical and optical properties, as well as surface topography of ZnO:Al layers grown on PET and PET/ZnSnOx substrates before and after wet‐chemical etching treatment, needed to maintain the advanced light management schemes in solar cells. A‐Si:H solar cells show an improvement in all photovoltaic parameters when ZnSnOx barrier layers are applied on PET substrates, leading to a remarkable increase in efficiency from 4.8 to 6.9%.

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“…Defect density increase in a-Si:H may be achieved with prolonged illumination [7], whereas c-Si:H is stable to the light soaking, and thus requires other methods to be modified. In our previous works [8][9][10][11][12] we presented experiments, utilizing 2 MeV electron irradiation and successive annealing, to achieve a defect density in a-Si:H and c-Si:H material and solar cells, which can be varied over several orders of magnitude. In the experiment, the spin density, N S , measured with electron spin resonance (ESR), was taken as a measure of the defect density.…”

Section: Introductionmentioning

confidence: 99%

“…In the experiment, the spin density, N S , measured with electron spin resonance (ESR), was taken as a measure of the defect density. Both solar cells and ESR samples are exposed to the same electron bombardmentannealing procedure, which enables us to investigate the recombination-related variations of cell performance [9][10][11][12]. In the present study we use data on both defect density [12] and illumination intensity dependencies obtained on the same set of a-Si:H and c-Si:H solar cells to investigate the relation between the absorber layer defect density and V OC using the simplest theoretical formulation given earlier for analysis.…”

Section: Introductionmentioning

confidence: 99%

Dependence of open circuit voltage in a-Si:H and μc-Si:H solar cells on defect density in absorber layer varied by 2 MeV electron bombardment

Astakhov

¹

,

Smirnov

²

,

CariusR.

³

et al. 2014

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Theoretically predicted values of the open circuit voltage (V OC ) for a-Si:H or c-Si:H based solar cells are substantially higher than the values achieved in of state-of-the-art devices. Fundamentally, open circuit voltage is determined by generation-recombination kinetics, where recombination is often controlled by the defect density in the absorber layer of a solar cell. The latter aspect is the focus of the paper. The relation between the V OC and the bulk recombination in the absorber layer is addressed in experiment by varying the defect density. The absorber layer defect density (spin density, N S , monitored with ESR) in a-Si:H and c-Si:H solar cells was varied over two orders of magnitude using a 2 MeV electron bombardment and successive stepwise annealing. The results of the electron bombardment experiment are analyzed with respect to the illumination intensity dependency of the V OC , measured for the same set of a-Si:H and c-Si:H solar cells. We find that the V OC of a-Si:H solar cells is not limited by defects in the bulk of the absorber layer, even at relatively high defect density up to 3-5 × 10 16 cm −3 and, therefore, other limiting mechanisms have to be identified to improve voltage in these devices. In contrast, c-Si:H solar cells show nearly classical V OC -N S relation. The bulk defect density in c-Si:H absorber layer is thus likely the key limiting factor for V OC in these devices at present status of material quality (N S of 3-7 × 10 15 cm −3 ). Further optimization of c-Si:H in terms of bulk defect density is highly relevant for V OC improvement in solar cells. PACS Nos.: 88.40.jj, 72.20.Jv, 61.80.Fe.Résumé : Les valeurs théoriques prédites pour le voltage en circuit ouvert (V OC ) de cellules solaires basées sur du a-Si : H ou du c-Si : H sont substantiellement plus élevées que celles que l'on obtient dans les dispositifs à la fine pointe. Fondamentalement, le voltage en circuit ouvert est contrôlé par la cinétique de la génération-recombinaison, où la recombinaison est souvent déterminée par la densité de défauts dans la couche absorbante de la cellule solaire. Ce dernier point est le sujet principal de cette publication. Nous étudions la relation entre V OC et la recombinaison en volume dans la couche absorbante en variant la densité de défauts. Par bombardement avec des électrons de 2 MeV, suivi de recuits successifs, nous varions sur deux ordres de grandeur la densité de défauts dans la couche absorbante (densité de spin, N S , vérifié par ESR) dans des cellules solaires de a-Si : H et de c-Si : H. Les résultats du bombardement électronique sont analysés en fonction de la dépendance de V OC sur l'intensité du bombardement, mesuré pour deux ensembles de cellules solaires a-Si : H et c-Si : H. Nous trouvons que V OC dans les cellules a-Si : H n'est pas limité par les défauts en volume de la couche absorbante, même à relativement grande densité jusqu'à 3-5 × 10 16 cm -3 et, par conséquent, d'autres mécanismes limitatifs doivent être identifiés pour améliorer le voltage dans ces dispositi...

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Relationship between absorber layer defect density and performance of a‐Si:H and µc‐Si:H solar cells studied over a wide range of defect densities generated by 2 MeV electron bombardment

Cited by 16 publications

References 57 publications

Numerical Design of Ultrathin Hydrogenated Amorphous Silicon-Based Solar Cell

Numerical Design of Ultrathin Hydrogenated Amorphous Silicon-Based Solar Cell

Influence of ZnSnO _x barrier layer on the texturing of ZnO:Al layers for light management in flexible thin-film silicon solar cells

Dependence of open circuit voltage in a-Si:H and μc-Si:H solar cells on defect density in absorber layer varied by 2 MeV electron bombardment

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Relationship between absorber layer defect density and performance of a‐Si:H and µc‐Si:H solar cells studied over a wide range of defect densities generated by 2 MeV electron bombardment

Cited by 16 publications

References 57 publications

Numerical Design of Ultrathin Hydrogenated Amorphous Silicon-Based Solar Cell

Numerical Design of Ultrathin Hydrogenated Amorphous Silicon-Based Solar Cell

Influence of ZnSnO x barrier layer on the texturing of ZnO:Al layers for light management in flexible thin-film silicon solar cells

Dependence of open circuit voltage in a-Si:H and μc-Si:H solar cells on defect density in absorber layer varied by 2 MeV electron bombardment

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Influence of ZnSnO _x barrier layer on the texturing of ZnO:Al layers for light management in flexible thin-film silicon solar cells