Anisotropy of singlet exciton diffusion in organic semiconductor crystals from ab initio approaches.
Anisotropy of singlet exciton diffusion in organic semiconductor crystals from ab initio approaches.
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DOI：
10.1063/1.4858464
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发表时间：
2014-01
期刊：
影响因子：
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通讯作者：
V. Stehr;B. Engels;C. Deibel;R. Fink
中科院分区：
文献类型：
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作者：
V. Stehr;B. Engels;C. Deibel;R. Fink
由于单重态激子扩散对有机光电子器件功能的重要性，准确模拟单重态激子扩散对预测新材料的性能至关重要。我们提出了一种协议，它允许用高水平从头算方法对激子输运进行有效的定向分析。它的依据是经常使用的费率公式的另一种选择，因为后者被发现在某些情况下是错误的。新方法可以与主方程结合使用，比相应的蒙特卡罗方法快得多。外推方案考虑了单重态激子耦合的长程特性。该方法被应用于单重态激子在这些物质中的扩散，在这些物质中，这些量在实验上得到了最好的确定：萘和菲。此外，晶体的高质量还减少了计算中使用的几何结构带来的不确定性。对于这些体系，我们的新方法给出了激子扩散长度L，这与实验符合得很好。以蒽为例，计算所得的L在一个方向上的值为58 nm，而实验值为60±10 nm。
Due to its importance for the function of organic optoelectronic devices, accurate simulations of the singlet exciton diffusion are crucial to predict the performance of new materials. We present a protocol which allows for the efficient directional analysis of exciton transport with high-level ab initio methods. It is based on an alternative to the frequently employed rate equation since the latter was found to be erroneous in some cases. The new approach can be used in combination with the master equation which is considerably faster than the corresponding Monte Carlo approach. The long-range character of the singlet exciton coupling is taken into account by an extrapolation scheme. The approach is applied to singlet exciton diffusion in those substances where these quantities are experimentally best established: naphthalene and anthracene. The high quality of the crystals, furthermore, diminish uncertainties arising from the geometrical structures used in the computations. For those systems, our new approach provides exciton diffusion lengths L for naphthalene and anthracene crystals which show an excellent agreement with their experimental counterparts. For anthracene, for example, the computed L value in a direction is computed to 58 nm while the experimental value is 60 ± 10 nm.