Sol–Gel Preparation of Transparent and Monolithic Nanocomposites with Fluorescent CuInS ₂ /ZnS Quantum Dots in Silica and for Luminescent Solar Concentrators

Transparent and fluorescent nanocomposite plates containing quantum dots (QDs) dispersed in a matrix are promising candidates for luminescent solar concentrators (LSCs), which have attracted considerable attention as transparent photovoltaic (PV) panels. However, the inherent tendency of nanoparticles to aggregate reduces transparency through enhanced light scattering and causes fluorescence quenching. To overcome this challenge, hydrophobic CuInS 2 /ZnS QDs, synthesized by thermal decomposition of Cu–In thiolate precursors, were hydrophilized through ligand exchange and homogeneously dispersed in tetramethylammonium silicate (TMAS) solution. The resulting fluorescent silica nanocomposites (QDs@silica) through the aqueous sol–gel process were transparent, monolithic, and suitable for LSC fabrication. LSC devices were prepared by coupling QDs@silica plates with a monocrystalline silicon PV module, and the effect of QD concentration on power generation was systematically investigated. Increasing QD concentration enhanced both photocurrent and power conversion efficiency. Spectral analysis revealed that this performance improvement originated from both QD luminescence and incident light scattering by QD aggregates. The maximum internal concentration factor C reached 0.35, comparable to reported values for nanophosphor-based LSCs. The TMAS-based sol–gel route will enable incorporation of various negatively charged nanoparticles, opening pathways toward LSCs with tailored luminescent and scattering properties. This approach provides a versatile strategy for advancing transparent PV technologies.