Luminescent solar concentrators (LSCs) improve solar cell performance by transforming the spectrally broad and partially diffuse solar spectrum into a spectrally narrow and focused light source, which is then concentrated onto a small-area solar cell. However, LSCs do not currently reach their full concentrating potential due to losses in the system that prevent luminescent light from reaching the edge of the concentrator, including light scattering and coupling to the escape cone. In order to reduce escape cone losses within LSCs, nanophotonic structures were designed for concentrators with CdSe/CdS core/shell nanocrystals. Using a combination of Monte Carlo ray-tracing simulations and FDTD simulations we show that concentration factor improvements of 3.7 times the standard concentrator are achievable when spectrally-selective mirrors are placed on top of the LSC. Further enhancements to the optical efficiency are possible when the emitted light is controlled either by a phase gradient metasurface or the directional emission of a nanophotonic stack of alternating high and low refractive index layers. Finally, we show that directional emission is also expected for a nanoscale thin film LSC on glass, which can also be fabricated by embedding CdSe/CdS in poly (cyclohexylethylene), a new polymer for LSC applications. To reduce scattering losses for LSCs, new surface ligands have been proposed for Si nanocrystals that improve dispersion in polymer matrices. In this collaboration, I characterized Si/poly (methyl methacrylate) composites and showed that the scattering losses are reduced by six fold using these new surface ligands when compared to previous methods. The design criteria established in this work demonstrate that nanophotonic structures can control the optical transport in LSCs, and that low scattering quantum dot/polymer composites are essential to realize high performance. The ability to control the light guiding properties in LSCs will be crucial for high quality LSCs and future implementation into building integrated photovoltaic technologies.