1. Nanostructures on Moth-eye
Templated Subwavelength-Structured Antireflection Coatings
for High-Efficiency Crystalline Silicon Solar Cells
Peng Jiang, Department of Chemical Engineering, University of Florida
Because of the high refractive index of silicon, more than 30% of incident light are reflected back from crystalline silicon, thus greatly impeding the conversion efficiency of Si photovoltaic devices. This proposal will develop an inexpensive and scalable colloidal templating approach to fabricate broadband moth-eye antireflection coatings (ARCs). We have successfully demonstrated several templating technologies for fabricating subwavelength-structured moth-eye ARCs on a large variety of technologically important substrates, including Si (both single-crystalline and multicrystalline), GaAs, GaSb, glass, and plastics. The templated moth-eye ARCs exhibit much improved broadband antireflection properties than traditional quarter-wavelength dielectric coatings. Normal-incidence reflection of less than 2% can be achieved on Si, GaAs and GaSb substrates. Optical reflection of less than 0.5% for all optical wavelengths can be achieved for polymer and glass substrates. The moth-eye coatings also exhibit superhydrophobic surface state once the aspect ratio of the nanopillars is higher than 10. This is important for developing self-cleaning ARCs for solar cells and other optoelectronic devices. We have also developed three theoretical models – RCWA, FDTD and TFM to simulate the optical reflection, transmission, and diffraction from the templated ARCs. These models help better understanding of the optical diffraction from subwavelength gratings, as well as rational design of moth-eye ARCs for different applications. We have shown that the RCWA and TFM models create almost equivalent results for subwavelenth-structured moth-eye gratings.
Templated Si Moth-eye ARC
Nanostructures on Moth-eye
Excellent Broadband Antireflection