Optical properties of TiO2 and disperse red-19 composite

Abstract Characteristic absorption and photoluminescence (PL) of TiO 2 and disperse red-19 (DR-19) composite have been investigated. Two step synthetic processes were employed to incorporate the DR-19 to the TiO 2 sol–gel. Firstly, urethane bonds between the DR-19 ( OH) and 3-isocyanatopropyl triethoxysilane (ICPTES, N C O) were fabricated (ICPDR) prior incorporation to the TiO 2 sol–gel. Secondary, hydrolysis of the ethoxy group from the ICPDR and condensation reaction between silanol groups from ICPDR and TiO 2 sol–gel were performed by adding ICPDR to the TiO 2 sol–gel and aged for several days at room temperature (ICPDRTiO 2 ). There was no absorption peak shift with increasing the DR-19 concentration in methanol. However, UV–visible absorption band was shifted toward red approximately 0.09 eV for the ICPDRTiO 2 film, which indicated the formation of dimmer or more aggregates. The PL peaks of ICPDRTiO 2 were red-shifted compared with DR-19 in methanol (0.12 eV) and ICPDR film (0.09 eV). The relatively large emission peak shift toward red could be due to the fluorescence resonance energy transfer (FRET) between DR-19 and TiO 2 in ICPDRTiO 2 matrix.