Antireflection and SiO2 Surface Passivation by Liquid-Phase Chemistry for Efficient Black Silicon Solar Cells: Preprint

Conference · Fri Jun 01 04:00:00 EDT 2012

OSTI ID:1044441

Yuan, Hao-Chih; Oh, Jihun; Zhang, Yuanchang; Kuznetsov, Oleg A.; Flood, Dennis J.; Branz, Howard M.

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 manufacturingcost 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. Prior tothis 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 SiO2on 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 decaymeasurement. 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.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
• DOE Contract Number: AC36-08GO28308
• OSTI ID: 1044441
• Report Number(s): NREL/CP-5200-54147
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
36 MATERIALS SCIENCE
ANTIREFLECTION COATINGS
CHEMISTRY
CURRENT DENSITY
DECAY
DEPOSITION
EFFICIENCY
ELECTRIC POTENTIAL
ETCHING
FURNACES
LIFETIME
MANUFACTURING
OPTIMIZATION
PASSIVATION
PERFORMANCE
PHOTONS
REFLECTION
SILICON SOLAR CELLS
SOLAR CELLS
SPECTRAL RESPONSE
WAVELENGTHS
antireflection coatings
black silicon
liquid-phase deposition
metal-assisted porous silicon etching
photovoltaic cells
surface passivation