Energy down converting organic fluorophore functionalized mesoporous silica hybrids for monolith-coated light emitting diodes

Abstract

The covalent attachment of organic fluorophores in mesoporous silica matrices for usage as energy down converting phosphors without employing inorganic transition or rare earth metals is reported in this article. Triethoxysilylpropyl-substituted derivatives of the blue emitting perylene, green emitting benzofurazane, and red emitting Nile red were synthesized and applied in the synthesis of mesoporous hybrid materials by postsynthetic grafting to commercially available MCM-41. These individually dye-functionalized hybrid materials are mixed in variable ratios to furnish a powder capable of emitting white light with CIE chromaticity coordinates of x = 0.33, y = 0.33 and an external quantum yield of 4.6% upon irradiation at 410 nm. Furthermore, as a proof of concept two different device setups of commercially available UV light emitting diodes, are coated with silica monoliths containing the three triethoxysilylpropyl-substituted fluorophore derivatives. These coatings are able to convert the emitted UV light into light with correlated color temperatures of very cold white (41100 K, 10700 K) as well as a greenish white emission with correlated color temperatures of about 5500 K.

Triazolyl Conjugated (Oligo)Phenothiazines Building Blocks for Hybrid Materials—Synthesis and Electronic Properties

“…Encouraged by our successful synthesis of fluorophore-containing silica hybrid materials from triazolyl ligated precursors [ 26 , 27 ] we reasoned this type of precursor ligation could be employ for embedding electrophores in the sense of an in-situ synthesis of meso-porous hybrid materials. Exemplarily the three triazolyl conjugated phenothiazine deri-vatives 3b , 3c , and 3d were chosen as substrates for the material synthesis.…”

“…Recently, we used CuAAC for preparing triethoxysilylated substituted fluorophore-containing precursors for the synthesis of Nile Red-embedded mesoporous silica hybrids as solvent polarity sensors that also operate in aqueous media [ 26 ]. Furthermore, we expanded the CuAAC approach for the synthesis of RGB fluorophore precursors that were used for mesoporous silica hybrid materials for energy down-converting phosphors and application in monolith coated light emitting diodes [ 27 ]. Based upon our experience in covalently anchoring phenothiazine electrophores in silica hybrid materials [ 28 ], either by postsynthetic grafting with carbamate linkers [ 29 ] or in-situ synthesis of the hybrid materials using the more hydrolysis stable urea linkers [ 30 ], we reasoned that CuAAC of phenothiazinyl alkynes with azido functiona-lized triethoxysilanes would provide highly luminescent, reversible redox systems that can be employed in hybrid silica in-situ synthesis.…”

Refined RGB Strategy for the Synthesis of Polymer‐Based Full Organic Luminescent Nanotubes with Broad Emission Bands

“…In this context, it is generally agreed that the brightness of the white light hinges on the green light, while the red and blue light simply play a role of adjusting the colour coordinate and colour temperature. [5] In the goal to apply this design principle to nanostructures, one of two pathways can be taken: (i) creating layer-upon-layer assembly to allow the creation of nanoscopic functional multilayer systems; [6][7][8][9][10] (ii) utilizing a multicomponent system.. [11][12][13][14] Recently, evidence has been obtained indicating that a broad wavelength emission can be successfully realized at the level of a single nanotube. This strategy was based on the spectral selection of two kinds of luminophores in order to minimize the potential charge and energy transfers.…”

“…In this context, it is generally agreed that the brightness of the white light hinges on the green light, while the red and blue light simply play a role of adjusting the colour coordinate and colour temperature [5] . In the goal to apply this design principle to nanostructures, one of two pathways can be taken: (i) creating layer‐upon‐layer assembly to allow the creation of nanoscopic functional multilayer systems; [6–10] (ii) utilizing a multicomponent system. [11–14] .…”

Diversity-Oriented Synthesis and Optical Properties of Bichromophoric Pyrrole-Fluorophore Conjugates

“…At usual concentration two chromophores emit independently in solution (Sarkar et al, 2016 ). Likewise this effect can also be achieved by embedding in micelles, organic or hybrid matrices (For recent examples of photochromic and multichromophoric emitters embedded in micelles or matrices, see e. g., Findlay et al, 2014 ; Shi et al, 2015 ; Bälter et al, 2016 ; Joshi et al, 2016 ; Börgardts and Müller, 2017 ; Pallavi et al, 2018 ). Far more challenging, however, is the conceptual design of unimolecular bi- or multichromophores capable of polychromic emission (for reviews on organic white light emitting devices and materials, see Mukherjee and Thilagar, 2014 , 2015 ; Wu and Ma, 2016 ).…”