Thin-film luminescent solar concentrators: A device study towards rational design

A study on the effect of different device parameters on the photophysical and photovoltaic behavior of thin-film luminescent solar concentrators (LSCs) is presented in this work. The concentration of the luminescent species, the thickness of the LSC film, the geometric gain of the LSC device and the composition and thickness of the white back reflector are systematically varied and their influence on LSC thin film properties and device performance is examined. It is shown that dye concentration and LSC film thickness have a major effect on the optical response of the LSC devices. The efficiency is found to decrease with increasing geometric gain, although saturation is observed for high geometric gains suggesting that LSC devices perform best for very large LSC areas. The surface roughness of the back reflector is found to play a key role in improving the efficiency of the LSC film because it induces a reduction of specular reflectivity and an increase of isotropic light scattering. The results of this study allow a greater understanding of the relationships between key LSC device parameters and the photophysical and photovoltaic behavior of planar thin-film LSC systems and provide useful guidelines for optimal design of thin-film LSC devices.