Adjustable emission of carbon dots and rhodamine B embedded in organic-inorganic hybrid gels for solid-state light devices

Transparent organic-inorganic SiO₂-PMMA nanocomposites with different fluorescent carbon dots (CD) and rhodamine B (RB) volume ratios were obtained. Their structural and photoluminescent properties were analyzed. FT-IR characterization reveals the presence of peaks associated with Si-OH and Si-O-Si from the silica inorganic network and peaks for C=C and C=O from the organic network given by poly methyl methacrylate (PMMA) and 3-trimethoxysilylpropyl methacrylate (TMSPM) coupling agent. Deconvolution analysis of the intrinsic luminescence of the hybrid matrix and the single embedded CD and RB hybrids was performed. The nanocomposite xerogels emission spectra show two emission peaks at 440 nm and 560 nm attributed to the CD and RB, respectively. The intensity of the emission bands is related to the variation in the CD/dye concentration ratio. Also, the estimated CIE 1931 chromaticity coordinates show that the global emission tonality of nanocomposites varies from blue to yellowish-orange. The CD/dye 2:2 volume ratio sample shows an emission tonality close to the white region (x = 0.35, y = 0.33). The low manufacturing cost of these nanocomposites and the incorporation of molecules with good luminescent intensity allow their potential application as coatings in solid-state lighting devices. Graphical Abstract: [Figure not available: see fulltext.]