Yu Ji, Lammi Robin, Gesquiere Andre J, Barbara Paul F
Center for Nano- and Molecular Science and Technology and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, USA.
J Phys Chem B. 2005 May 26;109(20):10025-34. doi: 10.1021/jp0506742.
Single molecule fluorescence correlation spectroscopy has been used to investigate the photodynamics of isolated single multichromophoric polymer chains of the conjugated polymers MEH-PPV and F8BT on the microsecond to millisecond time scale. The experimental results (and associated kinetic modeling) demonstrate that (i) triplet exciton pairs undergo efficient triplet-triplet annihilation on the <<30 micros time scale, (ii) triplet-triplet annihilation is the dominant mechanism for triplet decay at incident excitation powers > or =50 W/cm(2), and (iii) singlet excitons are quenched by triplet excitons with an efficiency on the order of (1)/(2). The high efficiency of this latter process ensures that single molecule fluorescence spectroscopy can be effectively used to indirectly monitor triplet exciton population dynamics in conjugated polymers. Finally, correlation spectroscopy of MEH-PPV molecules in a multilayer device environment reveals that triplet excitons are efficiently quenched by hole polarons.
单分子荧光相关光谱已被用于在微秒至毫秒时间尺度上研究共轭聚合物MEH-PPV和F8BT的孤立单多发色团聚合物链的光动力学。实验结果（以及相关的动力学建模）表明：（i）三重态激子对在<<30微秒时间尺度上经历高效的三重态-三重态湮灭；（ii）在入射激发功率>或 =50 W/cm²时，三重态-三重态湮灭是三重态衰变的主要机制；（iii）单重态激子被三重态激子淬灭，淬灭效率约为1/2。后一过程的高效率确保了单分子荧光光谱可有效地用于间接监测共轭聚合物中的三重态激子群体动力学。最后，多层器件环境中MEH-PPV分子的相关光谱表明，三重态激子被空穴极化子有效淬灭。
