Highly Luminescent and Stable Organic–Inorganic Hybrid Films for Transparent Luminescent Solar Concentrators

Here, a highly luminescent, stable, and visible-transparent organic-inorganic hybrid film was in situ synthesized in a siloxane-polyether (di-ureasil) sol-gel process by dissolving a 4-hydroxy-2-methyl-1,5-naphthyridine-3-carbonitrile (2mCND) ligand and a europium(III) ion. Doping a europium(III) complex into di-ureasil achieves an boost in photoluminescence quantum efficiency (PLQY) from 23.25 to 68.9%. In particular, the excellent photostability of the hybrid film was demonstrated after a 15 h aging experiment in strong UV-LED irradiation (∼468 mW/cm²). Compared to the polymethyl methacrylate (PMMA) matrix, di-ureasil containing a europium(III) complex shows an improved UV resistance, making it a promising candidate for various photonic applications. By integrating the hybrid film onto an acrylic substrate, a transparent luminescent solar concentrator (LSC) was fabricated, which reveals an optical conversion efficiency of ∼0.51% with a G factor of 3.1 at an optical transmission level of ∼90%. Such an LSC could be of particular interest in future transparent photovoltaic windows.