Sol–gel derived nanocomposite hybrids for full colour displays

Tuning the Photoluminescence of Silsesquioxanes with Short Substituted Urea Bridges

“…[13][14][15]17,18,20] The two emissions are related to radiative recombination mechanisms typical of donor/acceptor pairs. [17,20] However, the chemical species responsible for this emission have not been yet unequivocally addressed.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12] In particular, materials bearing urea groups in the organic bridge have received considerable attention in recent years due to their white light photoluminescence (PL). [13][14][15][16][17][18][19][20] Photoluminescent ureabridged silsesquioxanes are usually synthesized by the carboxylic acid solvolysis of the corresponding precursors containing terminal trialkoxysilyl groups. [16,18] In this process condensation reactions can be carried out in the absence of water, [21][22][23] leading to hybrid materials exhibiting high PL quantum yields.…”

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

“…[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. [28] For practical applications it is interesting to analyze the possibility of tuning the emission in different wavelength regions covering the whole visible spectrum.…”

Effect of silver nanoparticles on luminescent properties of europium complex in di-ureasil hybrid materials

“…The integrated areas of the organosiloxane T 1 , T 2 , and T 3 signals may be used to estimate the degree of hydrolysis/condensation of organic functional groups, which can be calculated with the equation C ¼ (T 1 +2T 2 +3T 3 )/3 (C designated as the degree of hydrolysis/condensation). Compared with the undoped di-ureasil matrix [6], the C value for the di-ureasil sample doped with lanthanide complex and nanoparticles reduces by ca. 3%, which is probably a result of incorporating complex and nanopaticles preventing the neighboring silanol groups (Si-OH) from condensation and results in the lower C. The excitation and emission spectra for d-U(600)-Eu and d-U(600)-Eu3.2 are shown in Fig.…”