Enhanced fluorescence emission and collection in luminescent solar concentrators: A theoretical investigation of integrated surface gratings and wavelength-selective reflectors

The Distributed Bragg Reflector (DBR) is a popular one-dimensional photonic crystal having a forbidden effect on photons within certain wavelength bands that can significantly reduce the surface escape loss in Luminescent Solar Concentrators (LSCs). However, DBR usually generates substantial reflectance sidelobes, which block photon incidence within the fluorescence absorption band and diminish LSC absorption capacity. In this study, a surface triangle grating integrated DBR for LSCs is designed, which increases the intensity of the electromagnetic field in the fluorescence layer due to waveguide mode resonance while also providing a complete reflective band with low reflectance sidelobes. As a result, more photons enter and are absorbed in the fluorescence layer, helping LSCs emit and collect fluorescence. In addition, a Monte Carlo ray-tracing algorithm is utilized to calculate various optical losses and light-collecting efficiency for LSCs. The results show that the triangle grating integrated DBR increases fluorescence emission, suppresses fluorescence escape, and improves light collection in the LSC, resulting in superior efficiency.