Transient analysis of organic electrophosphorescence. II. Transient analysis of triplet-triplet annihilation
Transient analysis of organic electrophosphorescence. II. Transient analysis of triplet-triplet annihilation
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DOI：
10.1103/physrevb.62.10967
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发表时间：
2000-10-15
影响因子：
3.7
通讯作者：
Forrest, SR
中科院分区：
文献类型：
--
作者：
Baldo, MA;Adachi, C;Forrest, SR
在前面的论文中，论文I [Phys. Rev. B 62，10 958（2000）]，我们研究了激子在几种磷光主客体分子有机体系中的形成和扩散。在本文中，我们证明了在有机电致发光器件中观察到的在高电流密度下电致磷光强度的降低[M。A. Baldo等人，Nature 395，151（1998）]主要是由于三重态-三重态湮灭。利用从瞬态磷光衰变中提取的参数，我们模拟了电致磷光器件的量子效率与电流特性。研究发现，激发态寿命较短的荧光粉的亮度增加主要是由于三重态-三重态湮没减少。我们还推导出一个表达式的极限电流密度（J（0））以上的三重态-三重态湮灭占主导地位。J（0）的表达式使我们能够建立识别有用的磷光体的标准，并帮助优化设计电致磷光分子和器件结构。
In the preceding paper, Paper I [Phys. Rev. B 62, 10 958 (2000)], we studied the formation and diffusion of excitons in several phosphorescent guest-host molecular organic systems. In this paper, we demonstrate that the observed decrease in electrophosphorescent intensity in organic light-emitting devices at high current densities [M. A. Baldo et al., Nature 395, 151 (1998)] is principally due to triplet-triplet annihilation. Using parameters extracted from transient phosphorescent decays, we model the quantum efficiency versus current characteristics of electrophosphorescent devices. It is found that the increase in luminance observed for phosphors with short excited-state lifetimes is due primarily to reduced triplet-triplet annihilation. We also derive an expression for a limiting current density (J(0)) above which triplet-triplet annihilation dominates. The expression for J(0) allows us to establish the criteria for identifying useful phosphors and to assist in the optimized design of electrophosphorescent molecules and device structures.