Poly(methyl methacrylate) Films with High Concentrations of Silicon Quantum Dots for Visibly Transparent Luminescent Solar Concentrators.

Silicon quantum dots (Si QDs) are attractive, non-toxic 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. Non-scattering 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 semi-transparent coatings for LSCs realized as solar harvesting windows.