Optical Excitations in Diphenylacetylene Based Dendrimers Studied by a Coupled Exciton Model with Off-Diagonal Disorder
Optical Excitations in Diphenylacetylene Based Dendrimers Studied by a Coupled Exciton Model with Off-Diagonal Disorder
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通过非对角无序耦合激子模型研究基于二苯乙炔的树枝状聚合物中的光学激发
DOI：
10.1142/s0217979299002514
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发表时间：
1999
影响因子：
1.7
通讯作者：
K. Harigaya
中科院分区：
文献类型：
--
作者：
K. Harigaya
提出了一个唯象耦合激子模型来描述扩展树枝状大分子中的光激发。在每个苯环上分配一个激子态，并考虑激子态之间服从高斯分布的最近邻跳跃积分。光激发能量相对于树枝状大分子尺寸的减小表明沿着树枝状大分子的主干存在激子漏斗。因此，扩展后的树枝状大分子可以作为人工分形天线系统来捕捉光能。通过求解光激发波函数的时间发展，研究了激子的动力学。结果表明，为了使在超分子外边缘捕获的光激发移到分子的中心区域，必须有一个一定大小的阻尼项。
A phenomenological coupled exciton model is proposed in order to characterize optical excitations in extended dendrimers. An onsite exciton state is assigned at each phenyl rings and a nearest neighbor hopping integral which obeys the Gaussian distribution is considered between the exciton states. The decreasing optical excitation energy with respect to the dendrimer size indicates the presence of exciton funnels along the backbone of the dendrimers. Therefore, the extended dendrimers can work as artificial fractal antenna systems which capture energy of light. Dynamics of an exciton is also investigated by solving time development of a wavefunction of optical excitations. It is shown that a damping term with a certain magnitude is necessary in order that optical excitations captured at the outer edge of the supermolecule move to the central areas of the molecule.