5(6)羧基荧光素敏化TiO2纳米粒子的光致电子转移的荧光特性研究

通过水解TiCl₄制备了锐钛矿结构TiO₂纳米粒子, 并用时间分辨荧光光谱研究了5(6)CFL(5(6)-Carboxyfluorescein, 简称5(6)CFL)染料敏化TiO₂纳米粒子体系的光致电子转移动力学. 5(6)CFL染料敏化TiO₂纳米粒子能形成电荷转移复合物, 这归因于染料分子的激发电子态波函数Ψ(D^*)与电荷分离态波函数Ψ(D⁺ +e^-)之间的耦合作用. 当激发5(6)CFL染料敏化TiO₂纳米粒子体系时, 电子以两种不同方式注入TiO₂纳米粒子导带: 第一, 通过5(6)CFL染料分子的激发态注入; 第二, 从电荷转移复合物(5(6)CFL/TiO₂)直接注入. 时间分辨荧光光谱表明, 在水溶液中纯5(6)CFL染料的荧光以寿命为τ₁=41 ps (74.4%) 和τ₂=3.22 ns (25.6%) 的双e指数衰减, 而5(6)CFL染料敏化TiO₂纳米粒子体系的荧光分别以时间常数为τ₁=44 ps (90.4%), τ₂=478 ps (8.6%) 和τ₃=2.41 ns (1.0%) 的三e指数衰减. 本文的研究工作能够为染料敏化太阳能电池的光致电子转移机理提供有价值的参考.

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

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（Ψ（D^*）） and the charge separated state（Ψ（D⁺+e^-））.On excitation of 5（6）CFL dyesensitized 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 lifetimesτ₁= 41 ps（74.4%） andτ₂ = 3.22 ns（25.6%）.However,5（6）CFL dye-sensitized TiO₂ nanoparticles have triple-exponential decay with lifetimes ofτ₁ = 44 ps（90.4%）,τ₂ = 478 ps（8.6%） andτ₃ = 2.41 ns（1.0%）.Our research will provide a valuable reference for the mechanism of dye-sensitized solar cell.