Exciton annihilation in a polyfluorene: Low threshold for singlet-singlet annihilation and the absence of singlet-triplet annihilation

被引：47

作者：

King, S. M. ^{[1
]}

Dai, D. ^{[1
]}

Rothe, C. ^{[1
]}

Monkman, A. P. ^{[1
]}

机构：

[1] Univ Durham, Dept Phys, Durham DH1 LHE, England

来源：

PHYSICAL REVIEW B | 2007年 / 76卷 / 08期

关键词：

D O I：

10.1103/PhysRevB.76.085204

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

Ultrafast photoinduced absorption measurements have been used to directly investigate singlet-singlet annihilation in polyfluorene. The pump fluence threshold for annihilation to dominate the decay was measured to be similar to 1 mu J cm(-2) corresponding to an excitation density of 1.5x10(17) cm(-3). The annihilation rate was found to be faster than that expected from a simple dipole-dipole interaction. This is ascribed to the additional influence of diffusion which, because of the dispersive nature of the exciton migration, has strong time dependence as the singlet excitons thermalize in the density of states as well as the expected intrinsic time dependence from a diffusion controlled process. Also, a comparable background level of triplets was created in the film to study the effect of singlet-triplet annihilation, which surprisingly, given the low threshold for singlet-singlet annihilation, was found to be negligible.

引用

页数：7

共 45 条

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