Silicon quantum dots with indirect bandgap photoluminescence are promising luminophores for large-area luminescent solar concentrators (LSCs). However, if commercially viable devices are to be achieved, silicon quantum dots must be dispersed within functional, light-guiding matrices such as acrylic slabs without losing their high photoluminescent quantum yield or succumbing to light-scattering agglomeration. With a goal of limiting scattering and producing functional LSC materials, we study silicon quantum dot/poly(methyl methacrylate) (PMMA) bulk polymerized composites. Ray-tracing Monte Carlo modeling predicts that scattering losses are significant for large-area silicon quantum dot LSCs unless the characteristic scattering length is at least as large as the LSC side length. We compare the effect of particle ligand choice on the nanocomposites, using particle loadings ranging from 0.06 to 0.50 wt %. We find that methyl 10-undecenoate functionalized silicon quantum dots in PMMA composites exhibit low levels of particle agglomeration, and thus light scattering, as compared to analogous silicon quantum dots capped with 1-dodecene. As a result, these ester-Si/PMMA composites show an improvement in light guiding compared to the alkane−Si composites, which is beneficial for future LSC applications.

Silicon quantum dots (Si QDs) are attractive, nontoxic luminophores for luminescent solar concentrators (LSCs). Here, we produced Si QD/poly(methyl methacrylate) (PMMA) films on glass by doctor-blading polymer solutions and achieved films with low light scattering at an order of magnitude higher Si QD weight fraction than has been achieved previously in the bulk. We suggest that the fast solidification rate of films as compared to slow bulk polymerization is an enabling factor in avoiding large agglomerates within the nanocomposites. Scanning electron microscopy confirmed that ∼100 nm or larger QD agglomerates exist in light-scattering films, and photoluminescence intensity measurements show that light scattering, if present, significantly reduces waveguiding efficiencies for LSCs. Nonscattering films fabricated in this work exhibit high ultraviolet absorption (>80%) paired with high visible transmission (>87%) and minimal visible haze (∼1%), making them well suited for semitransparent coatings for LSCs realized as solar harvesting windows.

The behavior of photochromic spiropyran (SP) dyes is greatly affected by the local environment in which they reside. Fluid microenvironments such as liquidlike polymers grant favorably fast dye decoloration whereas rigid microenvironments such as glassy polymers inhibit fast dye response. We study the use of disorganized but microphase-separated block polymer thermosets as photochromic dye hosts. These thermosets incorporate low glass transition temperature (T g) aliphatic polyester domains that facilitate rapid dye decoloration in a rigid poly­(methyl methacrylate) matrix by using a polymerization-induced microphase separation (PIMS) strategy. The spontaneous ring closing of SP was monitored in PIMS materials by UV–vis spectroscopy after irradiation with ultraviolet light. The rate of decoloration was found to be sensitive to a variety of molecular parameters including the molar mass and mass fraction of the polyester block, and the cross-link density of the poly­(methyl methacrylate) block allowing for tunability of the dye performance without changing the chemical identity of the components. Dye decoloration in the PIMS system could be controlled from two extremes: low T g homopolymer (t 1/2 = 170 s) behavior to bulk rigid polymer (t 1/2 = 1400 s) behavior. Through control over a variety of molecular parameters, we have been able to achieve fast decoloration rates in rigid and optically clear thermosets.

Thin film luminescent solar concentrators are promising components of distributed power generation systems for building integrated photovoltaic applications. However, thin film geometries require high luminophore loading fractions to achieve sufficient absorption of sunlight, which, in the case of nanocrystal luminophores, can lead to aggregation and light scattering. In this work, we integrate CdSe/CdS nanocrystals into thin films of poly(cyclohexylethylene) at a range of loading fractions and characterize the composites with a combination of spectroscopic and simulation tools. We find that increased incident sunlight scattering is observed for the increasing luminophore loading fraction, but that the scattering is mostly limited to higher energy sunlight such that visible transmittance and haze of the samples are all greater than 89.7% and less than 8.3%, respectively. We then analyze the refractive index of the composite and show that the increase in loading fraction also affects the propagation of photoluminescence in the film, especially if the refractive index of the film is greater than that of the substrate. These studies show the importance of understanding the optical transport within thin films and provide design criteria to fabricate thin films for future implementation into building integrated photovoltaic applications.

We describe the preparation of block polymer beads by aqueous suspension polymerization to create poly­(caprolactone) (PCL)-block-poly­(styrene-co-divinylbenzene) beads that can be selectively etched under basic conditions to yield mesoporous polymer microspheres with uniform pore size. Polyvinylalcohol was used to stabilize the suspension polymerization in which styrene and divinylbenzene monomers were polymerized from a PCL macrochain transfer agent (macroCTA). The resulting polymerization-induced microphase separation process led to a nanostructured bicontinuous morphology. The particle size and pore size were independently tunable: the particle size was controlled by the stir rate of the suspension polymerizationyielding average diameters ranging from 60 to 300 μmwhile the pore size was determined by the molar mass of the PCL block, with the mode pore diameters being 6 nm and 11 nm after etching beads made using 13 and 45 kg/mol PCL blocks, respectively. Based on nitrogen sorption measurements, the surface areas of the beads were ∼300 m2/g when using a PCL macroCTA of 13 kg/mol. The beads were homogenous throughout on the micron length scale as determined by confocal Raman microscopy and lacked an impermeable skin layer as confirmed by scanning electron microscopy. Furthermore, the scalability of suspension polymerization allows for the simple synthesis of large quantities of thermoset microspheres with uniform pore size. We also demonstrate the ability to incorporate functional pore walls into the beads using multiblock precursor polymers. These functionalized mesoporous polymer beads show high affinity for ionic dyes in aqueous solutions (as a proof of principle) and remove dye from the solution at rates exceeding those of commercial ion-exchange resins. The developed procedure could be used to generate other functional surface chemistries with important applications in heterogeneous catalysis, chromatography, and water remediation.