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

Building Integrated Photovoltaics (BIPVs) have been developed to aid in meeting new net-zero legislation. BIPVs incorporating Luminescent Solar Concentrators (LSC) are actively investigated to improve utilization of solar cells on vertical walls. However, LSCs suffer from low efficiency due to escape cone losses. One way to increase LSC efficiency is by using Asymmetric Light Transmission (ALT) interfaces that prevent light from escaping the LSC at angles around normal incidence. ALT interfaces consisting of trapezoidal alumina pyramids have been shown effective at light trapping when added to the light-entering surface of a polymethyl methacrylate (PMMA)-based LSC. However, the previous study overlooked the effect of azimuth angle of incidence. Given the geometry of the nanostructured interface, azimuth angle is anticipated to play a role in ALT interface performance. The goal of this paper is to investigate this aspect. Forward and backward transmission data and Poynting vector directional data were collected from COMSOLs Multiphysics Wave Optics Module for a trapezoidal pyramid ALT interface at varying azimuth angles. This data was then used with an in-house Monte Carlo Ray Tracing code to simulate light propagation within the LSC with the ALT interface and calculate the optical efficiency. Average transmission difference for increasing azimuth angles increased at lower polar angles yet decreased at higher polar angles. It was found that the optical efficiency for the ALT interface LSC improves in performance at higher azimuth angles compared to an LSC with a plain interface. This suggests that a horizontal orientation for the ALT interface LSC would be best for optimal performance.