Fabrication of CuInS2/ZnS quantum dot nanocomposite films and investigation of their influence on performance of soda glass-based luminescent solar concentrators

Abstract

The power generation performance of luminescent solar concentrators (LSCs) is decreased by unignorable optical losses including self-absorption of luminescence by the phosphor and optical absorption by the light guide plate. To address the optical loss due to self-absorption, this research focused on the use of core/shell CuInS₂ (CIS)/ZnS quantum dots (QDs) with a large Stokes shift. The QDs were dispersed in ethylene-vinyl acetate (EVA) copolymer to fabricate transparent fluorescent nanocomposite films. LSCs were prepared with the nanocomposite films and soda glass plate, a common building material to investigate the effect of optical absorption by the light guide plate on the power generation performance. Synthesized QDs showed yellow emission at 587 nm with a high photoluminescence quantum yield (PLQY) of 61.1%, and their large Stokes shift of 0.82 eV reduced self-absorption, making them suitable for LSC applications. We evaluated the effects of QD concentration, film thickness, light guide plate material, and film position on the performance of the LSCs. Optimized performance was observed at a QD concentration of 6.2 wt% and film thickness of 324 μm, showing 1.71-fold higher photocurrent and 3.58-fold larger area of incident photon-to-current efficiency spectrum compared to without film. Replacing soda glass with low-absorption white glass increased power generation by fourfold. This reveals the significant absorption losses of the PL and scattered incident light by soda glass. Despite the considerable optical loss, soda glass is a necessary component in a light guide plate to promote the use of LSCs as building materials. Our findings indicate that QDs with a narrow emission peak at ∼520 nm are required to minimize the absorption loss by soda glass.