Improving Dielectric Nanoresonator Array Coatings for Solar Cells

Abstract

Antireflection coatings based on dielectric nanosphere arrays are discussed in application to photovoltaic materials including silicon and gallium arsenide. We perform macro- and nanoscale characterization and finite-difference time-domain calculations demonstrating the enhanced optoelectronic properties. A significant absorptivity enhancement is achieved due to the collective resonant coupling of excited whispering gallery-like modes and thin-film interference effects. The resonant coupling is masked in macroscale measurements by the size variation of nanospheres, but it is clearly seen through imaging photocurrent at the nanoscale with near-field scanning photocurrent microscopy. The resonant coupling can be effectively tuned by the material, configuration, or size of nanospheres. Hybrid coatings combining nanospheres of different materials yield the highest efficiency gain, more than 30 %. We also evaluate an impact of manufacturing defects such as double layer formation. While the performance degrades, the antireflection coating still offers marked improvement in comparison with bare cells.

Large photocurrent density enhancement assisted by non-absorbing spherical dielectric nanoparticles in a GaAs layer

“…30% enhancement in photocurrent 13 . Whereas, Ha et al demonstrated experimentally more than 30% efficiency gain by using SiO 2 NPs on a GaAs solar cell 14 . These NPs were closely packed and worked as an antireflection coating (ARC).…”

“…This have captured the attention of scientific community recently and being investigated widely. Dielectric NPs at the front of solar cells have been demonstrated experimentally [10][11][12][13][14][15] and theoretically 8,[16][17][18][19] with improved device performance. Wan et al's TiO 2 NPs coated solar cell exhibited ca.…”

“…To the best of our knowledge, the simulated device structure in this study has not been yet reported theoretically or experimentally. Other structures such as NPs layer on a solar cell absorber 1 , 8 , 10 – 12 , 14 , 19 , NPs layer on a thin film ARC layer with an absorber layer 13 , 16 , 19 or NPs fully buried inside a thin film ARC layer with an absorber layer 31 have been studied extensively. Ha et al have reported more than 8% enhancement in the current density with 70% surface coverage by SiO 2 NPs on a GaAs solar cell at normal incidence comparing to a bare GaAs solar cell 11 .…”