Composite TiO2 film with quantum dots fabricated through a sol-gel process

A novel strategy has been developed to fabricate composite TiO2 films with CdTe quantum dots (QDs). Aqueous CdTe QDs with green-, yellow-, and red-emitting were prepared using thioglycolic acid as a capping agent. The QDs revealed high photoluminescence (PL) efficiencies under optimal preparation conditions. TiO2 sol was obtained by the controlling hydrolysis of tetrabutyl titanate in ethanol with poly(vinyl pyrrolidone). Diethanolamine was added to prevent the QDs from PL quenching generated by surface defects. After embedding the QDs in composite TiO2 film, the PL intensity of the QDs decreased because of the excitation and recombination between the QDs and TiO2. The PL peak wavelength of the QDs in films revealed a slight blue shift compared with their initial ones. The blue shift degree of the PL peaks depended on the properties of the QDs. Red-emitting CdTe QDs revealed a small blue shift of 1 nm while green-emitting ones revealed a blue shift of 7 nm. This indicated red-emitting QDs with high stability against incorporation. Facile preparation and excellent properties including high PL brightness, multicolor emission, and high stability make these films important applications in various fields.