Traditional concentrating photovoltaic (CPV) systems utilize multijunction cells to minimize thermalization losses, but cannot efficiently capture diffuse sunlight, which contributes to a high levelized cost of energy (LCOE) and limits their use to geographical regions with high direct sunlight insolation. Luminescent solar concentrators (LSCs) harness light generated by luminophores embedded in a light-trapping waveguide to concentrate light onto smaller cells. LSCs can absorb both direct and diffuse sunlight, and thus can operate as flat plate receivers at a fixed tilt and with a conventional module form factor. However, current LSCs experience significant power loss through parasitic luminophore absorption and incomplete light trapping by the optical waveguide. Here we introduce a tandem LSC device architecture that overcomes both of these limitations, consisting of a PLMA polymer layer with embedded CdSe/CdS quantum dot (QD) luminophores and InGaP micro-cells, which serve as a high bandgap absorber on top of a conventional Si photovoltaic. We experimentally synthesize CdSe/CdS QDs with exceptionally high quantum-yield (99%) and ultra-narrowband emission optimally matched to fabricated III-V InGaP microcells. Using a Monte Carlo ray-tracing model, we show the radiative limit power conversion efficiency for a module with these components to be 30.8% diffuse sunlight conditions. These results indicate that a tandem LSC-on-Si architecture could significantly improve upon the efficiency of a conventional Si photovoltaic module with simple and straightforward alterations of the module lamination steps of a Si photovoltaic manufacturing process, with promise for widespread module deployment across diverse geographical regions and energy markets.

Luminescent solar concentrators are currently limited in their potential concentration factor and solar conversion efficiency by the inherent escape cone losses present in conventional planar dielectric waveguides. We demonstrate that photonic crystal slab waveguides tailored for luminescent solar concentrator applications can exhibit >90% light trapping efficiency. This is achieved by use of quantum dot luminophores embedded within the waveguide that absorb light at photon energies corresponding to photonic crystal leaky modes that couple to incoming sunlight. The luminophores then emit at lower photon energies into photonic crystal bound modes that enable highly efficient light trapping in slab waveguides of wavelength-scale thickness. Photonic crystal waveguides thus nearly eliminate escape cone losses, and overcome the performance limitations of previously proposed wavelength-selective dielectric multilayer filters. We describe designs for hole-array and rod-array photonic crystals comprised of hydrogenated amorphous silicon carbide using CdSe/CdS quantum dots. Our analysis suggests that photonic crystal waveguide luminescent solar concentrators using these materials these can achieve light trapping efficiency above 92% and a concentration factor as high as 100.

This document contains 8 pages of supporting information, including 7 figures, 1 table, and 3 equations.

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Polymorph screening is a crucial step in the characterization and development of pharmaceuticals. The 1998 recall of ritonavir upon the unexpected appearance of the more stable Form II polymorph remains a notorious case of disappearing polymorphs as the presence of Form II inhibited the ability to grow the original Form I. This study presents the characterization of Form III of ritonavir grown from melt/cool crystallization. While Form III was observed in 2014, it was not characterized as a unique polymorph until 2022 when, coincidentally, a team at AbbVie and the authors of this manuscript independently discovered Form III via melt/cool crystallization. This study builds upon the discovery through a thorough characterization and novel thermal profile for quicker nucleation and crystallization of the new form.