Molecular stacking effect on photoluminescence quantum yield and charge mobility of organic semiconductors
Molecular stacking effect on photoluminescence quantum yield and charge mobility of organic semiconductors
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分子堆积效应对有机半导体光致发光量子产率和电荷迁移率的影响
DOI：
10.1039/c7cp05451c
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发表时间：
2017-11-28
影响因子：
3.3
通讯作者：
Wang, Chuan-Kui
中科院分区：
文献类型：
--
作者：
Fan, Jianzhong;Lin, Lili;Wang, Chuan-Kui
从理论上研究了高迁移率发光有机半导体2，6-二苯基蒽（DPA）和2，6-二苯基-9，10-双（苯乙炔基）蒽（DP-BPEA）的光致发光量子产率（PLQY）和电荷转移性质。采用量子力学/分子力学（QM/MM）方法研究了该体系的物理性质，用Marcus方程描述空穴和电子的转移速率，用动力学Monte Carlo模拟计算了电荷迁移率.计算了DPA和DP-BPEA在溶液和固相中的PLQY和电荷迁移率，分析了分子堆积效应。对于DPA，末端苯环的旋转运动在固相中受到明显的限制，导致Huang-Rhys因子和重组能的降低。这种受限的分子内旋转（RIR）效应抑制了激发态能量的耗散途径。结果表明，该发光体从四氢呋喃（THF）溶液到固相具有聚集诱导增强发射（AIEE）。而DP-BPEA的基态和激发态之间的几何变化从THF溶液到固相几乎没有变化，只有一个受限的键长（e. G. -C=C-）显示。DP-BPEA在THF溶液和固相中的荧光效率相近，但RIV不像RIR那样明显。此外，DPA和DP-BPEA晶体被证明是p型半导体。DPA的空穴迁移率（3.39 cm（2）V ~（-1）s ~（-1））大于DP-BPEA的空穴迁移率（1.62 cm（2）V ~（-1）s ~（-1））。我们的研究表明，有机半导体的不同分子堆积对其电子物理和电荷转移性质有重要影响。
The photoluminescence quantum yield (PLQY) and charge transfer property of the high mobility emissive organic semiconductors, 2,6-diphenylanthracene (DPA) and 2,6-diphenyl-9,10-bis(phenylethynyl) anthracene (DP-BPEA), are theoretically investigated. A quantum mechanics/molecular mechanics (QM/MM) method is adopted to investigate the photophysical properties, the Marcus equation is used to describe hole and electron transfer rates, and kinetic Monte Carlo simulation is performed to obtain charge mobility. In both solution and solid phase, the PLQY and the charge mobility of DPA and DP-BPEA are calculated, and the molecular stacking effect is analyzed. For DPA, the rotation motions of the terminal phenyl ring are obviously restricted in the solid phase, which results in the decrease of the Huang-Rhys factor and reorganization energy. This restricted intramolecular rotation (RIR) effect suppresses dissipation pathways of the excited state energy. As a result, the aggregation induced enhancement emission (AIEE) is thus revealed for this emitter from the tetrahydrofuran (THF) solution to the solid phase. However for DP-BPEA, the geometrical variations between the ground and excited states are almost unchanged from the THF solution to the solid phase, and only a restricted intramolecular vibration (RIV) of bond length (e. g. -C=C-) is displayed. As RIV is not obvious as RIR, a similar fluorescence efficiency is obtained for DP-BPEA in THF solution and the solid phase. In addition, DPA and DP-BPEA crystals are proven to be p-type semiconductors. The calculated mobility of the hole for DPA (3.39 cm(2) V-1 s(-1)) is larger than that of DP-BPEA (1.62 cm(2) V-1 s(-1)) because the number of effective transition pathways of DPA is more than that of DP-BPEA. Our study demonstrates that the different molecular stacking of organic semiconductors has an important effect on their photophysical and charge transfer properties.