Achieving High Efficiency in Luminescent Solar Concentrators Using Polymer Stabilized Cholesteric Liquid Crystal

Abstract

Luminescent solar concentrators (LSCs) combined with photovoltaic cells are in high demand, and it is a very effective way to increase the efficiency of a commercially available silicon solar panel. This is a promising solution for building integrated photovoltaics (BIPV) and could be a highly important element of our daily life for solar energy harvesting. Despite having high potential, the optical efficiencies of the currently available LSCs are not very high. In this paper, we report a scattering-enhanced optical efficiency of an LSC by incorporating a polymer-stabilized cholesteric liquid crystal with a high fluorescence organic dye between the two glass substrates. In the waveguiding layer, the chiral nematic director of the liquid crystal exhibits a random orientation; hence, scattering is observed in the film. These scattering elements increase the probability of light absorption of the dye in the ultraviolet region and subsequently enhance the re-emission of the light in the visible region. Moreover, the material shows a large Stokes shift and a very low overlap between the absorption and emission spectra. We have achieved a high optical efficiency of 37%, along with a concentration factor of more than 4.5 for the fabricated LSC. A Monte Carlo simulation has been developed to calculate the efficiency of the proposed device theoretically, and it shows good agreement with the experimental results. These findings create opportunities for developing highly efficient LSC windows capable of generating power for BIPV applications.