Colloquia

Summary

In 2024, more than half of the electricity generated in the Netherlands came from renewable sources. PV generation is one of the largest renewable energy sources and is expected to continue to grow in the coming decades. In densely populated areas such as the Netherlands, a competition with other sectors for available land arises from this growth. Next to this, cloudy weather is prominent in the Netherlands, mainly in winter. Incoming sunlight is diffused by clouds, decreasing the yield of PV. This results in intermittent power generation, straining the electricity grid. One way to mitigate these challenges is the use of a novel device developed in our research group. The Free-Space Luminescent Solar Concentrator (FSLSC) is a device that absorbs incoming (diffuse) sunlight and concentrates this onto, for example a PV panel, increasing winter yields by up to 60%.

A key material in the FSLSC are luminophore particles, that absorb light and emit them at a longer wavelength. Ytterbium doped lead-halide perovskite nanocrystals possessing high quantum efficiency, large stokes shift and down-conversion are investigated in this research as luminophore materials for the FSLSC. A novel synthesis route for the fabrication of nanocrystals, solvent-assisted mechanochemical synthesis, is investigated and optimized. This is a two-step process of ball milling with solvent to first synthesize a perovskite powder from precursors and then milling the powder into nanocrystals after addition of stabilizing ligands.

Different milling times for the powder step were investigated and it was found that milling times of 8 hours were sufficient to synthesize a pure powder phase. Prolonged milling times did not seem to degrade the powder or result in secondary phase formation. The second step, milling the powder into nanocrystals, was optimized using a design of experiment approach. Ligand concentration and milling time were used as parameters to optimize. Using XRD, PLQY, STEM and absorbance measurements, a local optimum was found at 48h milling time and 0,1 mL of stabilizing ligand. These results form the basis for a cost-effective, scalable production method for these luminophores.

Additionally, the environmental impact of these luminophores was investigated. For this, an inventory analysis was performed for several types of luminophores. The production process of the previously mentioned nanocrystals, an organic dye with high quantum yield, and Cd/Se, Cd/S core-shell quantum dots were investigated through hands-on knowledge and literature review. This information was used as input for a Life Cycle Analysis comparing the impact of these different luminophore materials.