Poly-crystalline silicon-oxide films as carrier-selective passivating contacts for c-Si solar cells

Yang, Guangtao; Guo, Peiqing; Procel, Paul; Weeber, Arthur; Isabella, Olindo; Zeman, Miro

doi:10.1063/1.5027547

Cited by 41 publications

(49 citation statements)

References 16 publications

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“…Therefore, into an attempt to obtain more transparent high‐thermal budget CSPCs, poly‐Si layer has been alloyed with oxygen or carbon and applied in FBC devices in combination with a‐Si:H–based CSPC at the textured front side . Notwithstanding the promising results at both passivation level and cell level, these alloys are still not optically optimal presenting higher absorption coefficient than c‐Si in the visible range and FCA in the NIR range, just like poly‐Si . Thus, to minimize these optical losses due to poly‐Si layers while keeping high their passivation quality, a careful surface engineering has to be performed.…”

Section: Introductionmentioning

confidence: 99%

“…33 Furthermore, poly-Si accounts for free carrier absorption (FCA) in the near infrared (NIR) wavelength range. 34 Therefore, into an attempt to obtain more transparent high-thermal budget CSPCs, poly-Si layer has been alloyed with oxygen 35,36 or carbon 37 and applied in FBC devices in combination with a-Si:H-based CSPC at the textured front side. 38,39 Notwithstanding the promising results at both passivation level and cell level, these alloys are still not optically optimal 35,40 presenting higher absorption coefficient than c-Si in the visible range and FCA in the NIR range, just like poly-Si.…”

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confidence: 99%

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Implantation‐based passivating contacts for crystalline silicon front/rear contacted solar cells

Limodio

Yang

Groot

et al. 2020

Progress in Photovoltaics

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In this work, we develop SiOx/poly‐Si carrier‐selective contacts grown by low‐pressure chemical vapor deposition and boron or phosphorus doped by ion implantation. We investigate their passivation properties on symmetric structures while varying the thickness of poly‐Si in a wide range (20‐250 nm). Dose and energy of implantation as well as temperature and time of annealing were optimized, achieving implied open‐circuit voltage well above 700 mV for electron‐selective contacts regardless the poly‐Si layer thickness. In case of hole‐selective contacts, the passivation quality decreases by thinning the poly‐Si layer. For both poly‐Si doping types, forming gas annealing helps to augment the passivation quality. The optimized doped poly‐Si layers are then implemented in c‐Si solar cells featuring SiO2/poly‐Si contacts with different polarities on both front and rear sides in a lean manufacturing process free from transparent conductive oxide (TCO). At cell level, open‐circuit voltage degrades when thinner p‐type poly‐Si layer is employed, while a consistent gain in short circuit current is measured when front poly‐Si thickness is thinned down from 250 to 35 nm (up to +4 mA/cm2). We circumvent this limitation by decoupling front and rear layer thickness obtaining, on one hand, reasonably high current (JSC‐EQE = 38.2 mA/cm2) and, on the other hand, relatively high VOC of approximately 690 mV. The best TCO‐free device using Ti‐seeded Cu‐plated front contact exhibits a fill factor of 75.2% and conversion efficiency of 19.6%.

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Section: Introductionmentioning

confidence: 99%

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confidence: 99%

Implantation‐based passivating contacts for crystalline silicon front/rear contacted solar cells

Limodio

Yang

Groot

et al. 2020

Progress in Photovoltaics

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“…Although further investigation is needed, these preliminary results suggest that the poly‐Si layers are perhaps partially oxidized during deposition or annealing. Based on recent reports in literature, such oxidation would help reduce parasitic absorption and hence improve current collection at the solar cell level …”

Section: Resultsmentioning

confidence: 99%

Approaching 23% with large‐area monoPoly cells using screen‐printed and fired rear passivating contacts fabricated by inline PECVD

Nandakumar

Rodriguez

Kluge

et al. 2018

Progress in Photovoltaics

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We present n‐type bifacial solar cells with a rear interfacial SiOx/n+:poly‐Si passivating contact (‘monoPoly’ cells) where the interfacial oxide and n+:poly‐Si layers are fabricated using an industrial inline plasma‐enhanced chemical vapor deposition (PECVD) tool. We demonstrate outstanding passivation quality with dark saturation current density (J0) values of approximately 3 fA/cm2 and implied open‐circuit voltage (iVoc) of 730 mV at 1‐sun conditions after firing in an industrial belt furnace. Using a simple solar cell process flow that can be easily adapted for mass production, a peak cell efficiency of 22.8% with a cell open circuit voltage (Voc) of 696 mV is achieved on large‐area, screen‐printed, Czochralski‐silicon (Cz‐Si) solar cells using commercial fire‐through metal pastes.

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“…This approach is of particular interest owing to its compatibility with industrial thermal budgets. Moreover, recent results report outstanding V oc values well above 700 mV [14], [18]- [25], anticipating conversion efficiency above 26% [3] when combining CSCs with IBC solar cell architecture. Like silicon heterojunction (SHJ) contacts based on hydrogenated amorphous silicon, the core of such high-efficiency devices stands on transport mechanisms.…”

Section: Introductionmentioning

confidence: 87%

Numerical Simulations of IBC Solar Cells Based on Poly-Si Carrier-Selective Passivating Contacts

Procel

Yang

Isabella

et al. 2019

IEEE J. Photovoltaics

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This paper presents an analysis of physical mechanisms related to operation and optimization of interdigitated back contact (IBC) poly-silicon-based devices. Concepts of carrier selectivity and tunneling are used to identify the parameters that impact on the fill factor. Then, based on technology computer-aided design (TCAD) numerical simulations, we describe the device performance in terms of transport and passivation. A validation of the model is performed by matching measured and simulated R, T, and external quantum efficiency spectra and electrical parameters. As result of such process, the opto-electrical losses of the reference device are identified. Then, we execute a study of the impact of process parameters on the performance of the IBC device under analysis. Assuming a uniform SiO 2 layer, simulation results reveal that both n-type and p-type poly-Si contacts can be theoretically perfect (i.e., approx. lossless), if assuming no interface recombination but considering tunneling of both carrier types. In other words, there exists an optimum oxide thickness (1 nm) for which majority carriers tunneling works already very well, and minority tunneling is still low enough to not result in significant recombination. Moreover, SiO 2 thickness up to maximum 1.6 nm is crucial to achieve high efficiency. Regarding rear geometry analysis, the efficiency curve as a function of emitter width peaks at 70% of pitch coverage. Further, it is shown that diffused dopants inside crystalline silicon make the device resilient to passivation quality. Finally, the calibrated model is used to perform an optimization study aiming at calculating the performance limit. The estimated performance limit is 27.3% for a 100-μm-thick bulk, 20-nm-thick poly-silicon layers, silver as rear contact, and double ARC. where he worked on advanced opto-electrical simulations of interdigitated back contacted solar cells. Since 2017, he has been with the Delft University of Technology as a Postdoctoral Researcher focusing on design and development of silicon heterojunction solar cells. His research interests include opto-electrical simulations and design of solar cells and semiconductor devices.Guangtao Yang received the Ph.D. degree from the Delft University of Technology, Delft, The Netherlands, in 2015, for his research on high-efficiency n-i-p thin-film silicon solar cells.Between 2015 and 2017, he was a Postdoctoral Researcher with the Delft University of Technology, focusing on poly-Si carrier-selective passivating contacts and their application in high-efficiency interdigital back-contacted c-Si solar cells. From January 2018 to June 2018, he was a Postdoctoral Researcher with the Eindhoven University of Technology. Since July 2018, he has been with the Delft University of Technology, working on carrier-selective passivating contacts based on poly-Si and its alloys, and transition metal-oxides.Olindo Isabella received the Ph.D. degree (cum laude) from the

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Poly-crystalline silicon-oxide films as carrier-selective passivating contacts for c-Si solar cells

Cited by 41 publications

References 16 publications

Implantation‐based passivating contacts for crystalline silicon front/rear contacted solar cells

Implantation‐based passivating contacts for crystalline silicon front/rear contacted solar cells

Approaching 23% with large‐area monoPoly cells using screen‐printed and fired rear passivating contacts fabricated by inline PECVD

Numerical Simulations of IBC Solar Cells Based on Poly-Si Carrier-Selective Passivating Contacts

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