Energy transfer probability in organic electrophosphorescence device with dopant

• 来源期刊: 中国物理(英文版)
• 关键词: electrophosphorescence energy transfer triplet
• 年，卷（期）: 2005,（12）
• 页码范围: 2590-2594
• 页数: 5页
• 语种: 英文

摘要

Based on the energy transfer process from host to dopant in an organic electrophosphorescent (EP) device, the expression of energy transfer probability (η) between the host (TPD) and guest (Ir(ppy)3) EP systems was proposed.The results show that: (1) The rate of the triplet energy transfer (KHG and KGH) increases exponentially with increasing donor-acceptor molecular distance (R), whereas decreases as the intermolecular distance (RHH) increases from 0.8 to 2.4 nm. Furthermore, KGH changes more quickly than KHG. (2) The energy transfer probability (η) increases as R reduces, and the RHH changes can be safely neglected for R ＜0.9 nm. The situation changes for 0.9nm＜ R ＜ 1.1nm,RHH (＜ 1nm) plays an essential role when η changes and increases with the latter. However, if R ＞ 1.1nm, the transfer probability will be below zero. Here, the energy transfer principle may be less important, and the high electroluminescence (EL) quantum efficiency of phosphorescent system will be attributed to the direct electron-hole recombination in phosphorescent molecules. (3) The ηwill increase when the Forster radius (R0) increases or Gibb's energy decreases.