中国物理B ›› 2005, Vol. 14 ›› Issue (12): 2590-2594.doi: 10.1088/1009-1963/14/12/034
代国章, 李宏建, 潘艳芝, 戴小玉, 谢强
Dai Guo-Zhang (代国章), Li Hong-Jian (李宏建), Pan Yan-Zhi (潘艳芝), Dai Xiao-Yu (戴小玉), Xie Qiang (谢强)
摘要: Based on the energy transfer process from host to dopant in an organic electrophosphorescent (EP) device, the expression of energy transfer probability ($\eta )$ 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 ($K_{\rm HG}$ and $K_{\rm GH})$ increases exponentially with increasing donor-acceptor molecular distance ($R$), whereas decreases as the intermolecular distance ($R_{\rm HH})$ increases from 0.8 to 2.4 nm. Furthermore, $K_{\rm GH}$ changes more quickly than $K_{\rm HG.}$ ({2}) The energy transfer probability ($\eta )$ increases as $R$ reduces, and the $R_{\rm HH}$ changes can be safely neglected for $R<$0.9 nm. The situation changes for 0.9nm$ < R < 1.1$nm, $R_{\rm HH }$ ($<1$nm) plays an essential role when $\eta $ changes and increases with the latter. However, if $R > 1.1$nm, 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 $\eta $ will increase when the Forster radius ($R_{0})$ increases or Gibb's energy decreases.
中图分类号: (Electroluminescence)