CAJ | 학술논문

蒽(anthracene)具有良好的热稳定性以及较高的荧光量子产率的优点,是最早用于研究有机发光器件(organic light-emitting device, OLED)的材料之一.在本文中,主要利用量子化学方法研究了不同外电场对蒽分子激发特性的影响规律.首先采用密度泛函理论(density functional theory, DFT)在6-311G(d, p)基组水平上对蒽分子基态结构进行优化,基于稳定基态结构,利用含时密度泛函(time-dependent density functional theory, TDDFT)以及同一基组水平,计算出蒽分子的前十个激发态的激发能、跃迁偶极矩、振子强度和紫外吸收光谱等数据.然后以密度泛函B3P86方法优化出的不同外电场下蒽分子基态结构为基础,使用TDDFT方法研究了不同外电场对蒽分子前线轨道能级和激发特性的影响规律.结果显示,无场时蒽分子在紫外区域234.50 nm处有一个较强的吸收峰,对应基态电子跃迁至第5激发态吸收光子波长;在外电场作用下,蒽分子电子由基态跃迁到激发态的各项光谱参数均有显著变化,加场后蒽分子的吸收光谱发生了红移,由紫外波段移向了紫外—可见光波段,与实验值相符合.分子前线轨道的计算结果也表明蒽分子的最高占据轨道(highest occupied molecular orbital, HOMO)和最低未占据轨道(lowest unoccupied molecular orbital, LUMO)能量差值在不同电场下存在差异.
은(anthracene)구유량호적열은정성이급교고적형광양자산솔적우점,시최조용우연구유궤발광기건(organic light-emitting device, OLED)적재료지일.재본문중,주요이용양자화학방법연구료불동외전장대은분자격발특성적영향규률.수선채용밀도범함이론(density functional theory, DFT)재6-311G(d, p)기조수평상대은분자기태결구진행우화,기우은정기태결구,이용함시밀도범함(time-dependent density functional theory, TDDFT)이급동일기조수평,계산출은분자적전십개격발태적격발능、약천우겁구、진자강도화자외흡수광보등수거.연후이밀도범함B3P86방법우화출적불동외전장하은분자기태결구위기출,사용TDDFT방법연구료불동외전장대은분자전선궤도능급화격발특성적영향규률.결과현시,무장시은분자재자외구역234.50 nm처유일개교강적흡수봉,대응기태전자약천지제5격발태흡수광자파장;재외전장작용하,은분자전자유기태약천도격발태적각항광보삼수균유현저변화,가장후은분자적흡수광보발생료홍이,유자외파단이향료자외—가견광파단,여실험치상부합.분자전선궤도적계산결과야표명은분자적최고점거궤도(highest occupied molecular orbital, HOMO)화최저미점거궤도(lowest unoccupied molecular orbital, LUMO)능량차치재불동전장하존재차이.
The theoretical investigations on the molecular energy levels, energy gaps, and the singlet–singlet electronic excitation properties (such as absorption spectra, excited energy, oscillator strengths) of the anthracene molecule in different external electric field were carried out by employing density functional theory (DFT) and time-dependent density functional theory (TDDFT) method with 6-311G(d, p) basis set. The stable molecular structure in ground state was optimized by DFT. The calculated results show that the absorption bands of anthracene molecule concentrate in ultraviolet region without external electric field, the absorption peak of which corresponds to the S0→S5 transitions with an excitation wavelength of 234.5 nm. The calculated absorption spectra agree well with the experimental data. Moreover, it is noticeable that the effects of the external electric field on optical properties cannot be neglected. The ultraviolet absorption spectra of anthracene molecule show a red shift into the blue-light region with the increases of electric field intensity. At the same time, the energy gaps between LUMO and HOMO for the anthracene molecule decrease with the increase of external electric field intensity. It can be shown that the anthracene molecule is promising as a useful blue-light emitting material through modulating by an electric field.