Universal measure of photon collection efficiency of dye luminescent solar concentrators

Abstract

Luminescent solar concentrators (LSC) are recently getting attention as promising components for use in building integrated photovoltaics (BIPV). Ongoing efforts to reduce their optical losses result in active search for new luminophores with large Stokes shift in order to reduce the reabsorption probability. Here we present a novel figure of merit for a large group of Gaussian dye luminophores that provides an accurate assessment of optical losses. Our approach originates in simplified analytical solution for spectral overlapping integral of absorption/emission bands and results in assessment of average reabsorption probability. The procedure is then generalized for any Gaussian dye LSC, by considering its basic parameters (Stokes shift, absorbance and size), thus resulting in a simple useful tool for designing practical LSC devices. Calculations are correlated with the experimental results of reabsorption probability obtained by measuring edge fluorescence spectra of various LSCs. • Width of gaussian spectral bands of molecules is related to Stokes shift. • Their relation enables prediction of reabsorption losses based on Stokes shift. • We numerically derive universally valid expression for losses of Gaussian dye LSCs. • Experiments on selected dye LSCs confirms the validity of our theoretical approach.