本論文有十五個模型分子，十四個為有機染料分子，一個為有機金 屬材料，分成四個系統做討論；第一個系統是以四併環噻吩當作中心 結構的不對稱型模型分子並討論噻吩單元擺放的位置及數量不同對於 雙光子的吸收有何影響；第二個系統為四取代十字型模型分子，屬於 簡易的有機分子模型，主要是討論推、拉電子基的強弱對雙光子吸收 有何影響；第三個系統為以咔唑為中心之多分歧型染料分子，探討增 加分子結構外圍的分歧數目在多光子吸收上有何表現；最後一個系統 是將鈣鈦礦製成量子點的新穎多光子吸收材料。 由這些模型分子的光學性質中，可以歸類出以下結論 : [1] 對於以四併環噻吩當作中心結構的不對稱型系統而言，將噻吩環 引入推電子基和中心結構中間的模型分子，具有最好的雙光子吸收表 現。 [2] 十字型分子結構末端的取代基拉電子能力越強，雙光子吸收會越 好；在此系統中，哌啶和二甲胺基對於分子內電荷轉移的影響相同。 [3] 若增加分子結構外圍的分支數目，其雙光子吸收截面值和三光子 激發效率值皆可以大幅提升。 [4] 利用飛秒雷射可以觀察到鈣鈦礦量子點的雙光子吸收表現。;Four different molecular systems are characterized and studied for their nonlinear absorption properties in this thesis. Among these four model systems, three are conjugated dye compounds with various molecular structures as follows: Series1: Tetrathienoacene-cored (TTA-cored) chromophores. Series2: Cruciform chromophores with various electron-donors and electron-acceptors. Series3: Carbazole-based muti-branched chromophores. The fourth model system is the perovskite quantum dot. Based on the measured linear and nonlinear optical properties, some features and structure-property relationships can be summarized: [1] For the TTA-cored dyes system, it is revealed that introducing a thiophene unit in between the electron-donating unit (i.e. triphenylamine) and TTA moiety will lead to promoted molecular two-photon absorptivity. [2] For the cruciform chromophores, the combination of electron-donor and electron-acceptors plays an important role for their two-photon-related properties. [3] For carbazole-based dye system, it is noted that both the two-photon and three-photon response are enhanced with the number of peripheral branches increased. [4] Two-photon absorption can be observed in perovskite quantum dot by femtosecond laser.
