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Title: Nano-photonic and nano-plasmonic enhancements in thin film silicon solar cells

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Publication Date:
Research Org.:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org.:
OSTI Identifier:
Report Number(s):
IS-J 8484
Journal ID: ISSN 0927-0248; PII: S0927024814002542
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Solar Energy Materials and Solar Cells; Journal Volume: 129; Journal Issue: C
Country of Publication:
United States

Citation Formats

Pattnaik, S., Chakravarty, N., Biswas, R., Dalal, V., and Slafer, D.. Nano-photonic and nano-plasmonic enhancements in thin film silicon solar cells. United States: N. p., 2014. Web. doi:10.1016/j.solmat.2014.05.010.
Pattnaik, S., Chakravarty, N., Biswas, R., Dalal, V., & Slafer, D.. Nano-photonic and nano-plasmonic enhancements in thin film silicon solar cells. United States. doi:10.1016/j.solmat.2014.05.010.
Pattnaik, S., Chakravarty, N., Biswas, R., Dalal, V., and Slafer, D.. Thu . "Nano-photonic and nano-plasmonic enhancements in thin film silicon solar cells". United States. doi:10.1016/j.solmat.2014.05.010.
title = {Nano-photonic and nano-plasmonic enhancements in thin film silicon solar cells},
author = {Pattnaik, S. and Chakravarty, N. and Biswas, R. and Dalal, V. and Slafer, D.},
abstractNote = {},
doi = {10.1016/j.solmat.2014.05.010},
journal = {Solar Energy Materials and Solar Cells},
number = C,
volume = 129,
place = {United States},
year = {Thu Jun 05 00:00:00 EDT 2014},
month = {Thu Jun 05 00:00:00 EDT 2014}
  • 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 densemore » 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 enhanced light-trapping.« less
  • For thin-film silicon solar cells (TFSC), a one-dimensional photonic crystal (1D PC) is a good back reflector (BR) because it increases the total internal reflection at the back surface. We used the plane-wave expansion method and the finite difference time domain (FDTD) algorithm to simulate and analyze the photonic bandgap (PBG), the reflection and the absorption properties of a 1D PC and to further explore the optimal 1D PC design for use in hydrogenated amorphous silicon (a-Si:H) solar cells. With identified refractive index contrast and period thickness, we found that the PBG and the reflection of a 1D PC aremore » strongly influenced by the contrast in bilayer thickness. Additionally, light coupled to the top three periods of the 1D PC and was absorbed if one of the bilayers was absorptive. By decreasing the thickness contrast of the absorptive layer relative to the non-absorptive layer, an average reflectivity of 96.7% was achieved for a 1D PC alternatively stacked with a-Si:H and SiO{sub 2} in five periods. This reflectivity was superior to a distributed Bragg reflector (DBR) structure with 93.5% and an Ag film with 93.4%. n-i-p a-Si:H solar cells with an optimal 1D PC-based BR offer a higher short-circuit current density than those with a DBR-based BR or an AZO/Ag-based BR. These results provide new design rules for photonic structures in TFSC.« less
  • The effects of Ag nano-strips with triangle, rectangular and trapezoid cross sections on the optical absorption, generation rate, and short-circuit current density of ultra-thin solar cells were investigated. By putting the nano-strips as a grating structure on the top of the solar cells, the waveguide, surface plasmon polariton (SPP), and localized surface plasmon (LSP) modes, which are excited with the assistance of nano-strips, were evaluated in TE and TM polarizations. The results show, firstly, the TM modes are more influential than TE modes in optical and electrical properties enhancement of solar cell, because of plasmonic excitations in TM mode. Secondly,more » the trapezoid nano-strips reveal noticeable impact on the optical absorption, generation rate, and short-circuit current density enhancement than triangle and rectangular ones. In particular, the absorption of long wavelengths which is a challenge in ultra-thin solar cells is significantly improved by using Ag trapezoid nano-strips.« less
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  • We investigated the growth mechanism of amorphous silicon thin films by implementing hot-wire chemical vapor deposition and fabricated thin film solar cell devices. The fabricated cells showed efficiencies of 7.5 and 8.6% for the samples without and with the rear-reflector decomposed by sputtering, respectively. The rear-reflector enhances the quantum efficiency in the infrared spectral region from 550 to 750 nm. The more stable quantum efficiency of the sample with the inclusion of a rear-reflector than the sample without the rear-reflector due to the bias effect is related to the enhancement of the short circuit current.