Reabsorption Losses in Luminescent Solar Concentrators: Effect of the Band Gap of Semiconductor Quantum Dots, their Size and Dispersion

Abstract

We investigate the effect of semiconductor quantum dots (QDs) radius r and its dispersion r on the re absorption during a luminescence process. QDs are promising as chromophores in luminescence solar concentrators (LSCs). To minimize detrimental reabsorption losses, six semiconduc tors, typically used to fabricate QDs, with a wide range of the bulk bandgaps Eg0 have been considered: CdS (Eg0 = 2.42 eV), CdSe (Eg0 = 1.67 eV), CdTe (Eg0 = 1.5 eV), InP (Eg0 = 1.27 eV), InAs (Eg0 = 0.355 eV), and PbSe (Eg0 = 0.27 eV). We prove that by adjusting the QD radius r and dispersion r, it is possible to optimize nanocrystal dimensions to minimize the reabsorption. It was shown that for the semiconductor bulk band gap range between 2.42 eV to 1.27 eV there is always the optimum QD size and its dispersion, at which the reabsorption is below the total experimental error of the measured normal ized both absorption coefficient and luminescence intensity. Further reduction of Eg0 increases the reabsorption at any val ues of r and r: for instance, for PbSe based QD with Eg0 = 0.27 eV, 1 nm mean radius and its 1% dispersion, the reabsorp tion reaches 54%. We estimate the width of the part of the solar spectrum, from which the photons contribute to the lumines cence processes. This is important for several LSCs, stalked on top of each other.