Tuning the Photoluminescence of Silsesquioxanes with Short Substituted Urea Bridges

Abstract

The polycondensation of a precursor synthesized by the reaction of 3‐(anilinepropyl)trimethoxysilane with 3‐(isocyanatopropyl)triethoxysilane led to a silsesquioxane bearing a substituted urea group in the short organic bridge. The self‐assembly of organic bridges, analyzed by SAXS and FTIR spectra, could be controlled by varying the conditions of the synthesis. Depending on the size of organic clusters, the silsesquioxane exhibited photoluminescence either in the green or red regions of the spectra, or an emission that could be tuned in the whole visible region by the excitation wavelength.magnified image

Efficient spectrally dynamic blue‐to‐green emission of bipyridine‐based bridged silsesquioxanes for solid‐state lighting

“…Moreover, the presence of the aromatic rings has the ability to increase the brightness and the emission quantum yield. Though efficient broad band emission has been reported for metal‐free hybrids 7–10, we are not aware of any reports showing converted blue‐to‐green light fabricated by pre‐coating metal‐free hybrid phosphors onto GaN‐based UV LEDs.…”

“…OIHs, mainly bridged silsesquioxanes, with stable Si–C bonds to ensure the organic loading targeting specific functionalities, are good candidates to achieve metal‐free phosphors for solid‐state lighting and addressed displays 7–10. In a recent study, we have shown that an amorphous bridged silsesquioxane bearing urea groups and a long alkyl chain exhibits a relatively high emission quantum yield (up to 0.24) 11, whereas its corresponding lamellar hybrid has much lower performances 12.…”

Transparent Polysilsesquioxane Films Obtained from Bridged Ureasil Precursors: Tunable Photoluminescence Emission in the Visible Region and Filtering of UV‐Radiation

“…The size of the resulting organic clusters depends on the competition between the rate of inorganic polymerization and the rate of self-assembly of organic bridges, [22] associated with the chemical structure and length of the organic bridge. [23] A distinctive characteristic of ureasils is their intrinsic photoluminescence arising from electron-hole recombinations in the inorganic domains (purplish-blue band) and photoinduced proton-transfer between urea groups convoluted with the emission from the inorganic clusters (blue band). [22][23][24][25][26][27][28][29][30][31] The location of both bands remains constant at low excitation wavelengths but a red-shift of both bands and a decrease in intensity is typically observed by increasing the excitation wavelength above a threshold value.…”

Boosting the Emission Quantum Yield of Urea Cross‐Linked Tripodal Poly(oxypropylene)/Siloxane Hybrids Through the Variation of Catalyst Concentration

“…[10][11][12] Emphasis has been given to those materials with a siliceous backbone and amine/amide functionalities because of both the higher emission quantum yield (up to 0.35) [13] ascribed to the presence of amine/amide groups and a siliceous phase. [10][11][12] Emphasis has been given to those materials with a siliceous backbone and amine/amide functionalities because of both the higher emission quantum yield (up to 0.35) [13] ascribed to the presence of amine/amide groups and a siliceous phase.…”

“…Concerning light‐emitting materials, in the last decade, several examples that illustrate the potential of organic–inorganic hybrids have emerged 10–12. Emphasis has been given to those materials with a siliceous backbone and amine/amide functionalities because of both the higher emission quantum yield (up to 0.35)13 ascribed to the presence of amine/amide groups and a siliceous phase 7,11,14.…”