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1. 中国石油大学 北京,102249
2. 西北大学, 光子学与光子技术研究所,陕西 西安,710069
纸质出版日期:2008-9-20,
收稿日期:2007-10-21,
修回日期:2007-12-12,
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钟寿仙, 李广山, 杜恭贺, 任兆玉. 并五噻吩分子光谱和激发态的密度泛函理论[J]. 发光学报, 2008,29(5): 821-826
ZHONG Shou-xian, LI Guang-shan, DU Gong-he, REN Zhao-yu. DFT Study on the Molecular Spectra and Excited State of Pentathienoacene[J]. Chinese Journal of Luminescence, 2008,29(5): 821-826
首次采用密度泛函理论(DFT)中的B3LYP方法
在6-31G(d)水平上对并五噻吩进行了构型优化
并作振动分析
未出现虚频.频率分析得到分子红外光谱和拉曼光谱
同时也得到分子的HOMO-LUMO能隙为3.86eV
所得计算结果与实验值基本符合.利用含时密度泛函理论(TDDFT)计算其激发态
得到振荡强度最大的五个允许跃迁的单激发态
所有激发态光谱均在紫外波段
故在可见光区域分子相对稳定
不易光致分解.对前线分子轨道HOMO和LUMO分析得到
HOMO到LUMO的跃迁是电子从C原子转移到S原子上
C-C原子之间形成离域键
这正是并五噻吩区别于一般有机材料而具有导电性的根本原因.结果表明:相对于并五苯
并五噻吩具有更高的稳定性
同时具有很好的导电性能和发光性能
是新一类有机半导体材料.
Pentacene is one of the most intensively studied systems among various organic semiconductors
for its relatively high field effect mobility and its ability to form ordered films.Nevertheless
pentacene suffers from the disadvantages of oxidative instability and
for display applications
a strong absorbance exists throughout the visible spectrum.Where photoinduced decomposition reactions could occur
this absorbance would make pentacene sensitive to most visible light.Compared to pentacene
there is an important small molecule semiconductor
that is thiophene-based materials exhibiting a variety of intraand intermolecular interactions-van der W aals interactions
weak hydrogen bandings
π-π stacking
sulfur-sulfur interactions-originating from the high polarizability of sulfur electrons in the thiophene rings.From the molecule structure
it can be analyzed that pentathienoacene(PTA) has high stability than pentacene owing to PTA's large band gap.These performances indicate PTA may have potential application in future organic electronics.However
the report on its application and basal physical characteristic obtained from experiment is few
and its theoretic research is much less.Quantum chemistry calculation can provide credible and valuable information for molecule study.In this paper
PTA molecule was calculated
including geometry model
infrared spectra
Raman spectra
HOMO-LUMO gap and the frontier molecular orbits by density function theory(DFT) for the first time
so the results can provide some reference informations for the future organic devices materials design theoretically.The infrared spectra and Raman spectra have been discussed and the spectra peaks of pentathienoacene were identified
the above datum on Raman spectra of PTA can provide the valuable reference for the experiment on PTA molecule identified.And at the same time
the HOMO-LUMO gap is gained:3.86 eV
which is very close to the experimental result.The five strongest allowable singlet excited states have been studied by TDDFT.The results indicate that all the energies of excited states were located in ultraviolet region
so PTA molecule is relatively stable under the visible light illumination because photoinduced decomposition reactions can not occur.The transition electron is diverted from carbon atom to sulfur atom
which can be seen through the frontier molecular orbits of pentathienoacene.Moreover
the formation of π-delocalized band leads to increase PTA molecule conductival.The results indicate that pentathienoacene is a new kind of organic semiconductor material and has perfect luminescence and electrical properties
especially
PTA has higher stability than pentacene.
密度泛函理论(DFT)并五噻吩红外光谱拉曼光谱激发态
density function theory (DFT)pentathienoaceneinfrared spectraraman spectraexcited state
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