Research of fluorescent properties of photo-induced electron transfer of 5(6)-carboxyfluorescein dye-sensitized TiO2 nanoparticles

Abstract

Anatased TiO2 nanoparticles were prepared by controlling hydrolysis of the TiCl4. Time-resolved fluorescence experiments were carried out to study the photo-induced electron transfer dynamics in the system of the 5(6)CFL dye-sensitized TiO2 nanoparticles. For the aboved system, the formation of the charge transfer complex is attributed to the coupling interaction between the wave functions of the excited electronic state of the dye ((D*)) and the charge separated state ((D++e-)). On excitation of 5(6)CFL dye-sensitized TiO2 nanoparticle system. The injection of electrons into the conduction band of TiO2 nanoparticles takes place in two different ways: through the excited state of the 5(6)CFL dye and through direct injection from the charge transfer complex. The time-resolved fluorescence experimental results indicate that the free 5(6)CFL dye in water has double-exponential decay with lifetimes1=41 ps (74.4%) and2=3.22 ns (25.6%). However, 5(6)CFL dye-sensitized TiO2 nanoparticles have triple-exponential decay with lifetimes of1=44 ps (90.4%),2=478 ps (8.6%) and3=2.41 ns (1.0%). Our research will provide a valuable reference for the mechanism of dye-sensitized solar cell.