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Title: 17.1%-Efficient Multi-Scale-Textured Black Silicon Solar Cells without Dielectric Antireflection Coating: Preprint

Abstract

In this work we present 17.1%-efficient p-type single crystal Si solar cells with a multi-scale-textured surface and no dielectric antireflection coating. Multi-scale texturing is achieved by a gold-nanoparticle-assisted nanoporous etch after conventional micron scale KOH-based pyramid texturing (pyramid black etching). By incorporating geometric enhancement of antireflection, this multi-scale texturing reduces the nanoporosity depth required to make silicon 'black' compared to nanoporous planar surfaces. As a result, it improves short-wavelength spectral response (blue response), previously one of the major limiting factors in 'black-Si' solar cells. With multi-scale texturing, the spectrum-weighted average reflectance from 350- to 1000-nm wavelength is below 2% with a 100-nm deep nanoporous layer. In comparison, roughly 250-nm deep nanopores are needed to achieve similar reflectance on planar surface. Here, we characterize surface morphology, reflectivity and solar cell performance of the multi-scale textured solar cells.

Authors:
; ; ;
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1019151
Report Number(s):
NREL/CP-5200-50707
TRN: US201114%%647
DOE Contract Number:
AC36-08GO28308
Resource Type:
Conference
Resource Relation:
Conference: Presented at the 37th IEEE Photovoltaic Specialists Conference (PVSC 37), 19-24 June 2011, Seattle, Washington
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; ANTIREFLECTION COATINGS; DIELECTRIC MATERIALS; ETCHING; MONOCRYSTALS; MORPHOLOGY; PERFORMANCE; REFLECTIVITY; SILICON; SILICON SOLAR CELLS; SOLAR CELLS; SPECTRAL RESPONSE; WAVELENGTHS; PV; BLACK SILICON; ANTIREFLECTION; MULTI-SCALE TEXTURE; PYRAMID BLACK ETCHING; Solar Energy - Photovoltaics

Citation Formats

Toor, F., Page, M. R., Branz, H. M., and Yuan, H. C.. 17.1%-Efficient Multi-Scale-Textured Black Silicon Solar Cells without Dielectric Antireflection Coating: Preprint. United States: N. p., 2011. Web. doi:10.1109/PVSC.2011.6185835.
Toor, F., Page, M. R., Branz, H. M., & Yuan, H. C.. 17.1%-Efficient Multi-Scale-Textured Black Silicon Solar Cells without Dielectric Antireflection Coating: Preprint. United States. doi:10.1109/PVSC.2011.6185835.
Toor, F., Page, M. R., Branz, H. M., and Yuan, H. C.. Fri . "17.1%-Efficient Multi-Scale-Textured Black Silicon Solar Cells without Dielectric Antireflection Coating: Preprint". United States. doi:10.1109/PVSC.2011.6185835. https://www.osti.gov/servlets/purl/1019151.
@article{osti_1019151,
title = {17.1%-Efficient Multi-Scale-Textured Black Silicon Solar Cells without Dielectric Antireflection Coating: Preprint},
author = {Toor, F. and Page, M. R. and Branz, H. M. and Yuan, H. C.},
abstractNote = {In this work we present 17.1%-efficient p-type single crystal Si solar cells with a multi-scale-textured surface and no dielectric antireflection coating. Multi-scale texturing is achieved by a gold-nanoparticle-assisted nanoporous etch after conventional micron scale KOH-based pyramid texturing (pyramid black etching). By incorporating geometric enhancement of antireflection, this multi-scale texturing reduces the nanoporosity depth required to make silicon 'black' compared to nanoporous planar surfaces. As a result, it improves short-wavelength spectral response (blue response), previously one of the major limiting factors in 'black-Si' solar cells. With multi-scale texturing, the spectrum-weighted average reflectance from 350- to 1000-nm wavelength is below 2% with a 100-nm deep nanoporous layer. In comparison, roughly 250-nm deep nanopores are needed to achieve similar reflectance on planar surface. Here, we characterize surface morphology, reflectivity and solar cell performance of the multi-scale textured solar cells.},
doi = {10.1109/PVSC.2011.6185835},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Jul 01 00:00:00 EDT 2011},
month = {Fri Jul 01 00:00:00 EDT 2011}
}

Conference:
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  • In this work we present 17.1%-efficient p-type single crystal Si solar cells with a multi-scale-textured surface and no dielectric antireflection coating. Multi-scale texturing is achieved by a gold-nanoparticle-assisted nanoporous etch after conventional micron scale KOH-based pyramid texturing (pyramid black etching). By incorporating geometric enhancement of antireflection, this multi-scale texturing reduces the nanoporosity depth required to make silicon `black' compared to nanoporous planar surfaces. As a result, it improves short-wavelength spectral response (blue response), previously one of the major limiting factors in `black-Si' solar cells. With multi-scale texturing, the spectrum-weighted average reflectance from 350- to 1000-nm wavelength is below 2% withmore » a 100-nm deep nanoporous layer. In comparison, roughly 250-nm deep nanopores are needed to achieve similar reflectance on planar surface. Here, we characterize surface morphology, reflectivity and solar cell performance of the multi-scale textured solar cells.« less
  • We report solar cells with both black Si antireflection and SiO2 surface passivation provided by inexpensive liquid-phase chemistry, rather than by conventional vacuum-based techniques. Preliminary cell efficiency has reached 16.4%. Nanoporous black Si antireflection on crystalline Si by aqueous etching promises low surface reflection for high photon utilization, together with lower manufacturing cost compared to vacuum-based antireflection coating. Ag-nanoparticle-assisted black Si etching and post-etching chemical treatment recently developed at NREL enables excellent control over the pore diameter and pore separation. Performance of black Si solar cells, including open-circuit voltage, short-circuit current density, and blue response, has benefited from these improvements.more » Prior to this study, our black Si solar cells were all passivated by thermal SiO2 produced in tube furnaces. Although this passivation is effective, it is not yet ideal for ultra-low-cost manufacturing. In this study, we report, for the first time, the integration of black Si with a proprietary liquid-phase deposition (LPD) passivation from Natcore Technology. The Natcore LPD forms a layer of <10-nm SiO2 on top of the black Si surface in a relatively mild chemical bath at room temperature. We demonstrate black Si solar cells with LPD SiO2 with a spectrum-weighted average reflection lower than 5%, similar to the more costly thermally grown SiO2 approach. However, LPD SiO2 provides somewhat better surface-passivation quality according to the lifetime analysis by the photo-conductivity decay measurement. Moreover, black Si solar cells with LPD SiO2 passivation exhibit higher spectral response at short wavelength compared to those passivated by thermally grown SiO2. With further optimization, the combination of aqueous black Si etching and LPD could provide a pathway for low-cost, high-efficiency crystalline Si solar cells.« less
  • The authors report on the optimization of textured-dielectric coatings for reflectance control in crystalline-silicon (c-Si) photovoltaic modules. Textured-dielectric coatings reduce encapsulated-cell reflectance by promoting optical confinement in the module encapsulation; i.e., the textured-dielectric coating randomizes the direction of rays reflected from the dielectric and from the c-Si cell so that many of these reflected rays experience total internal reflection at the glass-air interface. Some important results of this work include the following: the authors demonstrated textured-dielectric coatings (ZnO) deposited by a high-throughput low-cost deposition process; they identified factors important for achieving necessary texture dimensions; they achieved solar-weighted extrinsic reflectances asmore » low as 6% for encapsulated c-Si wafers with optimized textured-ZnO coatings; and they demonstrated improvements in encapsulated cell performance of up to 0.5% absolute compared to encapsulated planar cells with single-layer antireflection coatings.« less
  • This paper reports the use of SnO{sub 2} antireflection coatings deposited through direct liquid spraying of an aqueous solution of SnCl{sub 4} on randomly upward pyramid textured (100)-Si solar cells. In spite of the adverse characteristic of the process used, the pyramid-like texture was preserved after the film deposition. The hemispherical reflectance of the sprayed-SnO{sub 2}/textured-Si structure was comparable to those obtained using conventional techniques.