含不同杂原子共轭单元的有机光敏染料的超快发光动力学

摘要

The ultrafast photoluminescence dynamics of three organic dyes—C210,C214,and C216—with different conjugated linkers containing various heteroatoms,such as bifuran,bithiophene and biselenophene,in combination with dihexyloxy-substituted triphenylamine (TPA) as the electron donor and cyanoacrylic acid (CA) as the electron acceptor have been studied systematically.The excited-state dynamics of the three dyes were investigated in detail in different media:tetrahydrofuran (THF) and toluene (PhMe) solutions,polymethyl methacrylate (PMMA) and polystyrene (PS) polymer films,and the surfaces of alumina and titania films in contact with an ionic liquid composite electrolyte.These dyes were found to feature dynamic Stokes shifts in all the aforementioned media,indicating stepwise intramolecular relaxations of the non-equilibrium excited state.The electron injection yield was distinctly lower for the non-equilibrium excited state than the equilibrium excited states,which can be ascribed to the competition between torsional relaxation and electron injection.A broad time scale over one magnitude of order was presented for electron injection due to the great energy losses originating from the multiple torsional relaxations,which should be controlled for future dye design and device development.Moreover,despite the shorter lifetimes of the equilibrium excited states for C210 and C216 than C214,the electron injection yields of equilibrium excited states for all the dyes are comparable due to the accelerated electron injection rate.%系统研究了含有不同杂原子的共轭单元(联呋喃、联噻吩及联硒酚)的三种有机染料C210、C214和C216的超快发光动力学,双己氧基取代的三苯胺作为电子给体,氰基丙烯酸作为电子受体.详细考察了三种染料分别在不同媒介中的激发态动力学:四氢呋喃及甲苯溶液、聚甲基丙烯酸甲酯及聚苯乙烯聚合物薄膜、氧化铝及二氧化钛薄膜表面.发现在以上介质中都普遍存在动态斯托克斯位移现象,表明发生了非平衡激发态的分子内多步弛豫过程.由于扭转弛豫和电子注入过程之间的竞争作用,非平衡激发态的电子注入产率比平衡激发态的低得多.此外,由于激发态能量弛豫导致的能量损失,电子注入时间常数变化超过了一个数量级,这在未来的染料设计及器件发展中应进行控制.三种染料在平衡激发态处的电子注入效率相近,由于C210和C216加快的电子注入速率补足了它们较C214小的平衡激发态寿命.