双偶氮苯-二苯并[b,i]噻蒽-[2,3-b]苯-5,7,12,14-四酮衍生物分子的二阶非线性光学性质

Theoretical study on the second-order nonlinear optical properties of bisazo-dibenzo[b,i]thianthracene-[2,3-b]benzene-5,7,12,14-tetrone derivative molecules

使用密度泛函理论(DFT)M06-2X方法、采用6-311+g(d,p)基组,分别对26个双偶氮-二苯并[b,i]噻蒽-[2,3-b]苯-5,7,12,14-四酮衍生物分子进行结构优化与频率计算;使用含时密度泛函理论(TD-DFT)TD-M06-2X方法计算了a1~d6分子的前线分子轨道与电子吸收光谱,采用有效场FF方法研究了二阶非线性光学性质(NLO).研究结果表明,26个噻蒽四酮类衍生物分子的能隙在1.33—2.02 eV范围,归属于有机半导体;最低能量吸收峰波长在601.8~609.5nm范围;在增大分子的二阶非线性光学系数β_(μ)(或β_(0))值方面,含相同偶氮苯基团或含不同偶氮苯基团分别引入到二苯并[b,i]噻蒽-[2,3-b]苯-5,7,12,14-四酮分子两侧的2,10位优于2,9位,在2,10位分别端接含推、拉基团的偶氮苯优于含相同给电子基团的偶氮苯.在偶氮苯苯环对位分别端接强吸电子基(-NO_(2))与强供电子基(如-N(CH_(3))_(2)、-N(Ph)_(3)、-N-苯基咔唑等)可增强体系的二阶非线性光学性能,获得性能良好的非线性光学材料.

The geometric configuration optimizing and frequency operation of 26 bisazo-dibenzo[b,i]thianthracene-[2,3-b]benzene-5,7,12,14-tetrone(DNTBTRA)derivative molecules were studied by density functional theory(DFT)M06-2X method at 6-311+g(d,p)basis set level.Specifically,frontier orbitals,electronic absorption spectra and second-order nonlinear optical(NLO)properties were calculated by the time-dependent density functional theory(TD-DFT)TD-M06-2X method.The results show that band gaps of 26 thiaanthracene tetraketone derivative molecules range from 1.33-2.02 eV,belonging to organic semiconductors;and the wavelength of the weakest absorption peak ranges from 601.8 to 609.5 nm.Moreover,the 2,10 sites substitution of same azobenzene groups or different azobenzene groups were superior to 2,9 sites in the DNTBTRA molecule,and substituting azobenzene groups with donor-acceptor electronic redicel at the 2,10 sites of the DNTBTRA molecule were superior to azobenzene groups with the same electron donating group,both of which contribute to increasing the second-order nonlinear optical coefficient β_(μ)(or β_(0))of the DNTBTRA molecule.The para-sites of azobenzene rings substituted by strong electron withdrawing groups(-NO 2)and strong electron donating groups(such as -N(CH_(3))_(2),-N(Ph)_(3),-N phenylcarbazole,in which order the values of β_(0) increases)were found to be beneficial to improve the second-order NLO property of the system,resulting in second-order NLO materials with excellent performance.