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Author

Yuguo Tao

Other affiliations: University of New South Wales
Bio: Yuguo Tao is an academic researcher from Georgia Institute of Technology. The author has contributed to research in topics: Passivation & Silicon. The author has an hindex of 11, co-authored 22 publications receiving 412 citations. Previous affiliations of Yuguo Tao include University of New South Wales.

Papers
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Journal ArticleDOI
TL;DR: In this article, a carrier-selective tunnel oxide passivated rear contact for high-efficiency screen-printed large area n-type front junction crystalline Si solar cells was proposed.
Abstract: This paper reports on the implementation of carrier-selective tunnel oxide passivated rear contact for high-efficiency screen-printed large area n-type front junction crystalline Si solar cells. It is shown that the tunnel oxide grown in nitric acid at room temperature (25°C) and capped with n+ polysilicon layer provides excellent rear contact passivation with implied open-circuit voltage iVoc of 714 mV and saturation current density J0b′ of 10.3 fA/cm2 for the back surface field region. The durability of this passivation scheme is also investigated for a back-end high temperature process. In combination with an ion-implanted Al2O3-passivated boron emitter and screen-printed front metal grids, this passivated rear contact enabled 21.2% efficient front junction Si solar cells on 239 cm2 commercial grade n-type Czochralski wafers. Copyright © 2016 John Wiley & Sons, Ltd.

83 citations

Journal ArticleDOI
TL;DR: In this article, the fabrication of front junction n-type Si solar cells on 239 cm 2 Cz using ion implanted boron emitter and phosphorus back surface field (BSF) in combination with screen printed metallization was reported.

43 citations

Journal ArticleDOI
TL;DR: In this article, the authors reported on in-depth understanding, modeling, and fabrication of 23.8% efficient 4 cm2 n-type float zone (FZ) silicon cells with a selective boron emitter and photolithography contact on front and tunnel oxide passivating contact on the back.
Abstract: This paper reports on in-depth understanding, modeling, and fabrication of 23.8% efficient 4 cm2 n-type Float Zone (FZ) silicon cells with a selective boron emitter and photolithography contact on front and tunnel oxide passivating contact on the back. Tunnel oxide passivating contact composed of a very thin chemically grown silicon oxide (∼15 A) capped with plasma-enhanced chemical vapor deposition (PECVD) grown 20 nm n+ poly Si gave excellent surface passivation and carrier selectivity with very low saturation current density (∼5 fA/cm2). A high-quality boron selective emitter was formed using ion implantation and solid source diffusion to minimize metal recombination and emitter saturation current density. Process optimization resulted in a cell $V_{{\rm{oc}}}$ of 712 mV, $J_{{\rm{sc}}}$ of 41.2 mA/cm2, and FF of 0.811. A simple methodology is used to model these cells which replaces tunnel oxide passivating contact region by electron and hole recombination velocities extracted from measured saturation current density of tunnel oxide passivating contact region and analysis. Using this approach and two-dimensional device modeling gave an excellent match between the measured and simulated cell parameters and efficiency, supporting excellent passivation and carrier selectivity of these contacts. Extended simulations showed that 26% cell efficiency can be achieved with this cell structure by further optimization of wafer quality, emitter profile, and contact design.

37 citations

Journal ArticleDOI
TL;DR: In this paper, a selective boron emitter (p+/p++) was developed by a screen-printed resist masking and wet chemical etch-back process, which first grows a porous Si layer and subsequently removes it.
Abstract: Front metal contact induced recombination and resistance are major efficiency limiting factors of large-area screen-printed n-type front junction Si solar cells with homogeneous emitter and tunnel oxide passivated back contact (TOPCON). This paper shows the development of a selective boron emitter (p+/p++) formed by a screen-printed resist masking and wet chemical etch-back process, which first grows a porous Si layer and subsequently removes it. Various wet-chemical solutions for forming porous Si layer are investigated. An industrial compatible process with sodium nitrite (NaNO2) catalyst is developed to uniformly etch-back the ∼47 Ω/◻ atmospheric pressure chemical vapor deposited heavily doped boron emitter to ∼135 Ω/◻ by growing a 320 nm porous Si layer within 3 min and subsequently removing it. After etching back, the boron emitter was subjected to a thermal oxidation to lower the surface concentration and the emitter saturation current density J0e. Various etched-back emitters were evaluated by meas...

33 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, the efficiency of n-type silicon solar cells with a front side boron-doped emitter and a full-area tunnel oxide passivating electron contact was studied experimentally as a function of wafer thickness W and resistivity ρ b.

470 citations

Journal ArticleDOI
TL;DR: It is demonstrated experimentally that a back reflector with plasmonic Ag nanoparticles can provide light-trapping performance comparable to state-of-the-art random textures in n-i-p amorphous silicon solar cells.
Abstract: Plasmonic metal nanoparticles are of great interest for light trapping in thin-film silicon solar cells. In this Letter, we demonstrate experimentally that a back reflector with plasmonic Ag nanoparticles can provide light-trapping performance comparable to state-of-the-art random textures in n-i-p amorphous silicon solar cells. This conclusion is based on the comparison to high performance n-i-p solar cell and state-of-the-art efficiency p-i-n solar cells deposited on the Asahi VU-type glass. With the plasmonic back reflector a gain of 2 mA/cm2 in short-circuit current density was obtained without any deterioration of open circuit voltage or fill factor compared to the solar cell on a flat back reflector. The excellent light trapping is a result of strong light scattering and low parasitic absorption of self-assembled Ag nanoparticles embedded in the back reflector. The plasmonic back reflector provides a high degree of light trapping with a haze in reflection greater than 80% throughout the wavelength r...

402 citations

Journal ArticleDOI
TL;DR: In this paper, the authors discuss the design guidelines for passivating contacts and outline their prospects, and present an overview and classification of work to date on passivating contact structures in c-Si solar cells.
Abstract: To further increase the conversion efficiency of crystalline silicon (c-Si) solar cells, it is vital to reduce the recombination losses associated with the contacts. Therefore, a contact structure that simultaneously passivates the c-Si surface while selectively extracting only one type of charge carrier (i.e., either electrons or holes) is desired. Realizing such passivating contacts in c-Si solar cells has become an important research objective, and an overview and classification of work to date on this topic is presented here. Using this overview, we discuss the design guidelines for passivating contacts and outline their prospects.

263 citations

Journal ArticleDOI
TL;DR: In this paper, the state-of-the-art bifacial solar PV technology is described based on a comprehensive examination of nearly 400 papers published since 1979 (approximately 40% are referenced in this work) focused on illuminating additional research and development opportunities to enhance and assess performance and expand Bifacial technology's overall contribution within a rapidly expanding global solar market.
Abstract: Bifacial solar photovoltaics (PV) is a promising mature technology that increases the production of electricity per square meter of PV module through the use of light absorption from the albedo. This review describes current state-of-the-art bifacial solar PV technology based on a comprehensive examination of nearly 400 papers published since 1979 (approximately 40% are referenced in this work) focused on illuminating additional research and development opportunities to enhance and assess performance and expand bifacial technology׳s overall contribution within a rapidly expanding global solar market. Research and development efforts on bifacial PV should continue to emphasize improved efficiency in cells, module reliability and deployment configuration of bifacial arrays in a PV plant to co-optimize front-backside energy production during the entire day for fixed and tracking systems. Research on improved conversion efficiencies associated with monofacial PV cells will also continue to benefit bifacial PV performance. Standardization of certification procedures for bifacial PV technology performance efficiency and expansion of niche applications is required to promote wider deployment worldwide.

253 citations