Cd-free quantum dots for transparent luminescent solar concentrators

Cd-free UV-absorbing quantum dots (QDs) were synthesized and applied to transparent luminescent solar concentrators (LSCs). At first, a synthesis method to fabricate CuInS2/ZnS QDs was developed and optimized, tuning time and temperature and characterizing the reaction product. Afterwards, the prepared QDs were employed as luminescent compound in polymeric thin film LSCs and reference systems with the benchmark luminophore Lumogen red were built. The matrices employed were PMMA, fluoro-copolymer A and the polymeric blend PMMA-fluoro-copolymer A. Once the system was optimized, an extensive study aimed at evaluating the variation of the device efficiency as function of the luminophore concentration was performed. Concerning QDs, it was found an increase of the efficiency increasing the luminophore concentration as expected. This is mainly due to the high Stokes shift of CuInS2/ZnS that avoids re-absorption losses and their no-quenching of fluorescence by aggregation. This aspect is in contrast to the maximum-like trend of efficiency vs concentration for the organic luminophores. Therefore QDs LSC demonstrates to be a highly promising in BIPV application as LSC windows. Thereafter, the durability of the LSCs systems having PMMA and fluoro-copolymer matrices was assessed through accelerated weathering (1000h). It was proved the high durability of the fluorinated matrix and it was found that the luminophore has to be optimized for the matrix employed due to the high interaction luminophore-matrix. Finally, a preliminary study of the application of QDs in down-shifting was performed.