本篇論文以具有高熱穩定性1,4-bis(carbazolyl)benzene作為分子之中心結構，於分子週邊連接diphenylamine、phenyl、diphenyl、methyl、-F、-NO2等不同取代基，以DFT B3LYP/6-31G*在Gaussian98 軟體套件下計算，藉以探討加入不同取代基對此具有電洞傳輸性質之分子可能產生之影響。結果顯示，加入diphenylamine、phenyl、diphenyl、methyl等取代基會使分子的HOMO能階上升，其能力如下：diphenylamine > methyl> diphenyl > phenyl，而加入拉電子取代基則會導致HOMO能階下降，下降幅度-NO2>-F。同時，隨著各種取代基數量增加，會使分子之Energy gap-3 (HOMOneutral-HOMOcation)下降，其取代基影響能力為diphenylamine≒diphenyl>phenyl>methyl≒ -F ≒ -NO2。而在游離能方面，加入拉電子取代基會導致分子之游離能上升；而加入其他取代基則會使得分子之游離能下降，其中又以diphenylamine效果最好，其順序如下：diphenylamine>diphenyl>phenyl≒methyl。其中，加入diphenylamine之1,4-bis(carbazolyl)benzene衍生物，其具有較接近ITO電極功函數之HOMO能階、較小的Energygap-3、較低之游離能、較大之共軛體系(可預期具有較高之Tg)以及較均勻之電荷分佈，因此可以推論加入diphenylamine取代基之該類分子具有較佳之電洞傳輸性能。

In this study, we chose the 1,4-bis(carbazolyl)benzene as the core moiety of the molecule,which with high thermal stability,and conjugated with different substituent groups , including diphenylamine , phenyl , diphenyl , methyl , -F and -NO2 . To use the DFT B3LYP/6-31G* basic set in Gaussian98 program, to investigate the influences of the hole-transporting property of the molecules when conjugated with different substituent groups. When molecules conjugated with the diphenylamine , phenyl , biphenyl and methyl , the HOMO level will rise , and the order was : diphenylamine > methyl> biphenyl > phenyl ; when introduced the electron-withdraw substituents , the HOMO level will descend , and -NO2 > -F . Moreover, when the amount of substituents were increased, the Energy gap-3 (HOMOneutral-HOMOcation) were decreased, and the order was : diphenylamine ≒ biphenyl > phenyl > methyl ≒ -F ≒ -NO2 . In the aspect of ionization potential(IP) , the IP will increase while introduced with the electron-withdraw substituents , and will decrease while introduced with the electron-donate substituents , the order was as follow : diphenylamine > biphenyl > phenyl ≒ methyl . In all case , the derivatives were formed by diphenylamine conjugated with 1,4-bis(carbazolyl)benzene was found having comparative HOMO level with the work-function of the ITO ,the smallest Energy gap-3 , the smallest IP , the biggest conjugation system (to have the higher Tg as expecting ) and uniform electron distribution , therefore , we can infer these molecules might possess excellent hole transporting property .

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