Invited Paper EM+EN-ThA7
Controlling Light Absorption with Nanophotonics

Thursday, October 22, 2015, 4:20 pm, Room 211C

Luminescent solar concentrators (LSCs) offer many advantages over traditional concentrator geometries. As opposed to concentrators that rely on tracking, LSCs operate under both direct and diffuse illumination and require the solar cell to only be efficient at a small range of wavelengths. In practice, most LSCs suffer losses from reabsorption of emitted light, non-unity quantum yields, and incomplete light guiding to the solar cell. Here we combine tunable lumophores based on quantum dot heterostructures with photonic designs to improve the concentration efficiency of LSCs and study light propagation within the device.

To achieve high concentration ratios it is critical to have high effective Stokes shifts, high quantum yields, and to reduce escape cone losses. We synthesized a series of core-shell nanocrystal lumophores that exhibit tunable emission. We show how the narrow emission bandwidth of these nanocrystals enables the use of a 1D photonic mirror on the top surface of the device, designed to admit incident sunlight and trap luminesced light from the nanocrystal. In combination, the concentration ratios from these devices exceed the performance of dyes with higher quantum yields but broader emission. Another approach to photonic LSCs is to restrict the angle of emission from the lumophores to promote coupling to the total internal reflection modes of the LSC. This talk will discuss designs for the latter approach and compare achievable concentration factors.

The second portion of the talk will discuss light management strategies for solid-state lighting, and the incorporation of plasmonic nanostructures to enhance light outcoupling from solid-state devices. This section of the talk will compare and contrast plasmonic structures for solar cells and solid-state lighting, and discuss ways that design rules should be adjusted for different materials systems.