Session: K9-05: RADIATIVE COOLING AND RADIATIVE PROPERTIES OF NANOMATERIALS

Paper Number: 121281

121281 - Modeling Periodic Asymmetric Light Transmitting Nanostructures for Luminescent Solar Concentrators Using COMSOL Multiphysics Wave Optics Module 

Abstract: 

The global push for net-zero initiatives, particularly in building legislation, is a pivotal step in reducing the significant contribution of greenhouse gas emissions from buildings worldwide. Building Integrated Photovoltaics (BIPVs) have been investigated over the years to take advantage of large surface areas for harvesting solar energy to reach net-zero. In particular, Luminescent Solar Concentrators (LSCs) can improve the performance of Photovoltaic (PV) cells at less optimal angles. LSCs act as a waveguide, focusing solar energy on a large transparent plastic surface area towards a much smaller surface area solar cell. LSCs also contain luminescent species within the plastic that provide a shift in small wavelengths, which are more efficiently absorbed by the solar cell. Although LSCs can enhance the efficiency of PV cells at these angles, the system still falls short in its ability to perform.

 

Approximately 50-70% of radiation that enters the LSC escapes from the light-receiving surface through what is known as the "escape cone." To mitigate this type of loss, multiple methods have been investigated. Spectrally selective mirrors, photonic crystals, and utilizing luminescent species are all methods that show improvement in top surface losses, yet current research limits the range of wavelengths and incidence angles that interact with the top surface. Asymmetric Light Transmitting (ALT) nanostructures take into account the vast wavelength range of light emitted from the sun as well as the incidence angle. These nanostructures are laid out periodically on the top surface of an LSC and have a trapezoidal geometry. They allow for all diffraction orders to propagate through the nanostructure, particularly from a low to high index of refraction, and prevent backward transmission of higher diffraction orders. A previous study has proposed and theoretically investigated these nanostructures but only looked at varying the wavelength and polar incident angles.

 

The objective of this work is to define the predicted properties of the ALT nanostructure reported by varying the wavelength, polar incident angle, and azimuthal angle to obtain the transmission behavior of the ALTs. The ALT nanostructure was modeled using COMSOL’s Multiphysics Wave Optics Module and was validated using the azimuth angle study performed in a previous study. The presented geometric model was made of alumina material on top of a Polymethyl methacrylate (PMMA) substrate and surrounded by a box of air. Floquet periodic conditions were applied to the lateral sides for implementing periodicity of the nanostructures. Port boundaries were also applied to the top of the air box as well as the bottom of the substrate to control propagation and collect the light interacting with the nanostructure. Preliminary results show that as the polar incident angle and azimuth angle increase, the difference between forward and backward transmission decreases, thus reducing the chance for light to be trapped within the substrate. It is also important to note that as the wavelength increases, this difference in transmission behavior decreases even further. This study helps to illustrate the true potential of incorporating ALT nanostructures to the light-receiving surface of an LSC for improving efficiency.

Presenting Author: Hannah Arnow Rensselaer Polytechnic Institute

Presenting Author Biography: Hannah Arnow is a PhD student studying Mechanical Engineering at Rensselaer Polytechnic Institute focusing on energy harvesting systems. Specifically, her research explores ways to improve energy conversion in emerging systems, such as luminescent solar concentrators.

Authors:

Hannah Arnow Rensselaer Polytechnic Institute
Vincent Oliveto Air Force Research Laboratory
Duncan Smith Distributed Solar Development, LLC
Michael Hughes Rensselaer Polytechnic Institute
Diana-Andra Borca-Tasciuc Rensselaer Polytechnic Institute