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Title: Nano-photonic structures for light trapping in ultra-thin crystalline silicon solar cells

Thick wafer-silicon is the dominant solar cell technology. It is of great interest to develop ultra-thin solar cells that can reduce materials usage, but still achieve acceptable performance and high solar absorption. Accordingly, we developed a highly absorbing ultra-thin crystalline Si based solar cell architecture using periodically patterned front and rear dielectric nanocone arrays which provide enhanced light trapping. The rear nanocones are embedded in a silver back reflector. In contrast to previous approaches, we utilize dielectric photonic crystals with a completely flat silicon absorber layer, providing expected high electronic quality and low carrier recombination. This architecture creates a dense mesh of wave-guided modes at near-infrared wavelengths in the absorber layer, generating enhanced absorption. For thin silicon (<2 μm) and 750 nm pitch arrays, scattering matrix simulations predict enhancements exceeding 90%. Absorption approaches the Lambertian limit at small thicknesses (<10 μm) and is slightly lower (by ~5%) at wafer-scale thicknesses. Parasitic losses are ~25% for ultra-thin (2 μm) silicon and just 1%–2% for thicker (>100 μm) cells. There is potential for 20 μm thick cells to provide 30 mA/cm2 photo-current and >20% efficiency. Furthermore, this architecture has great promise for ultra-thin silicon solar panels with reduced material utilization and enhancedmore » light-trapping.« less
Authors:
 [1] ; ORCiD logo [2] ;  [2]
  1. Ames Lab. and Iowa State Univ., Ames, IA (United States); CSIR-National Physical Lab., New Delhi (India)
  2. Ames Lab. and Iowa State Univ., Ames, IA (United States)
Publication Date:
Report Number(s):
IS-J-9314
Journal ID: ISSN 2079-4991; NANOKO; PII: nano7010017
Grant/Contract Number:
AC02-07CH11358
Type:
Accepted Manuscript
Journal Name:
Nanomaterials
Additional Journal Information:
Journal Volume: 7; Journal Issue: 1; Journal ID: ISSN 2079-4991
Publisher:
MDPI
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; nano-photonics; solar cell; light-trapping; scattering
OSTI Identifier:
1357794