The initial portion of this talk will discuss the combination of quantum dots with plasmonic nanostructures for enhanced luminescence efficiency, comparing the effects of controlling the radiative rates with designs to enhance and direct luminescence over large area films.
We will then discuss the design and considerations behind photonic luminescent solar concentrators. Luminescent solar concentrators offer many advantages over traditional concentrator geometries, including the ability to capture diffuse illumination, and the potential for integration with architectural materials. In a standard LSC design, incident sunlight is absorbed by a luminophore embedded within a plastic sheet, re-emitted at longer wavelengths that are trapped by total internal reflection, and eventually concentrated to an edge-mounted solar cell. Although promising, such devices suffer from losses including reabsorption of the emitted light by the luminophore, non-unity quantum yields, and incomplete light guiding to the solar cell.
Recent work has focused on the development of luminescent materials based on colloidal nanocrystals with large Stokes shifts to overcome the reabsorption losses. These colloidal nanocrystals hold other advantages as luminescent materials, as their narrow emission bandwidth enables the use of photonic structures that address other light guiding losses. Such photonic designs must operate over a broad spectral range and range of incident angles. By combining luminescent materials with photonic structures, longer propagation lengths and higher concentration factors can be reached.
One of the key advantages of these luminescent nanocrystals is their tunability. Here we focus particularly on core-shell quantum dot heterostructures. We will show the effects of tuning the luminophore shape on the conversion efficiency, with respect to both the changing optical properties due to quantum confinement effects and the scattering due to the volume of the nanocrystal. Using a wavelength-selective photonic mirror, which is designed to accept blue light and trap the luminescent light, we then explore how the combination of a tunable luminophore and tunable photonic structure can be implemented to improve light guiding efficiency. Finally, we will compare different photonic designs for implementation with these nanocrystals.