本論文合成出一系列含苯併噻吩(benzo[c]thiophene)結構之雙極性線型化合物，並研究將其應用於染料敏化太陽能電池或光伏打電池之結果。化合物的分子設計上，以9、10位置含雙乙烷或雙2-乙基己基烷取代基之芴(fluorene)作為線型分子共軛架橋(conjugated spacer)，並於兩端分別連接胺取代電子予體(electron donor)及腈取代電子受體(electron acceptor)。其中化合物N1因以2-腈基丙烯酸(2-cyanoacrylic acid)同時作為為電子受體及鉗合基(anchoring group)，因而可作為染料敏化太陽能電池之材料；而化合物N2−N5含丙二腈基(malononitrile)，可做為光伏打電池之材料。此系列化合物具有不錯的光收成，其最大吸收波長在487–556 nm的範圍，且消光係數約在21,900–35,300 M-1cm-1之間。相較於芴片段有乙基取代化合物N1與N2，化合物N4可能由於芴片段上較推電子之雙2-乙基己基烷取代而具有較紅位移和較高莫耳消光係數之吸收。而化合物N5雖然缺少明顯的推電子胺基而使得吸收波長較小，但仍因雙2-乙基己基烷取代而具有高消光係數。經由理論計算可發現，這些分子的苯併噻吩與相鄰的芴基團有較大之二面角(39.4–42.0o)，而噻吩基與二腈基乙烯間之二面角相對較小(0.5–1.3o)。另外，化合物的低能態吸收皆具有電荷轉移的特徵，並有極高(0.62–1.16)的振子強度(oscillator strength)。以本系列雙極性分子作為p-type材料，掺以不同比例的PCBM (phenyl-C61-butyric acid methyl ester)作為n-type材料，可製作出光伏打電池元件。從元件結果顯示當乙基取代化合物N2與PCBM以 1:1的掺混比例製作時，元件有最佳的轉換效率(0.56%)。由於本系列化合物HOMO能階較低，元件皆有高開環電壓(0.67–0.98 V)，而元件的電流密度則受到材料及PCBM的掺混濃度而有極大的改變。於乙基系列化合物N2–N3中，電流密度在PCBM的掺混濃度為80%時為最小；而於雙2-乙基己基烷化合物N4–N5中，其電流密度則隨PCBM的掺混濃度增加而增加。我們亦藉由原子力顯微鏡(Atomic Force Microscopy，AFM) 來觀看N2與N5製作成元件主動層(active layer)之表面型態(morphology)。由結果發現N2元件在與PCBM掺混比例1:1、1:2及1:4時的均方根粗糙度(R.M.S. roughness)分別為0.320、0.266及0.212 nm，顯示三者的薄膜有不錯的平整度。另外，異辛烷取代化合物N5與PCBM的掺混材料，其均方根粗糙度依1:1、1:2、1:4的比例依次為0.387、0.302、0.205 nm，平整度較N2元件稍差。

A series of linear dipolar compounds containing benzo[c]thiophene unit have been synthesized and applied for dye-sensitized solar cells or photovoltaics. These molecules consist of 9,10-diethyl or 9,10-bis(2-ethylhexyl) fluorene as the conjugated spacer, a diphenylamine as the electron donor and an cyano-containing group as the electron acceptor. Compound N1 adopting a 2-cyanoacrylic acid as the electron acceptor and the anchoring group can be used as the sensitizer of dye-sensitized solar cells, while compounds N2−N5 utilizing a dicyanovinylene group as the acceptor can be used as the sensitizer of photovoltaic cells. All of these compounds have fairly high molar absorption coefficients (21,900–35,300M-1cm-1) at the region between 487–556 nm. Compound N4 which has two 2-ethylhexyl substitutuents at 9-position of the fluorene segment exhibits higher molar extinction coefficient and more red-shifted absorption wavelength than analogues N1 and N2 which have two ethyl substituents at the same position. Though compound N5 absorbs at the highest-energy region because of the absence of an amino donor, it still possesses a large absorption coefficient due to the two 2-ethylhexyl substituents. Theoretical calculations indicate that these compounds N1−N5 possess fairly small dihedral angles between the neighboring aromatic rings of the conjugated spacer (0.5−1.3o) except that between benzothiophene and the neighboring fluorene group (39.4−42.0o). The lowest-lying transitions of these compounds have considerable charge-transfer character with high oscillator strength (0.62−1.16). The bulk-heterojunction photovoltaic devices utilize the benzothiophene-containing compounds as the donor material and PCBM (phenyl-C61-butyric acid methyl ester) as the acceptor were also investigated. The photovoltaic cell fabricated with N2 with PCBM blending ratio of 50 wt% turn out to have the highest power conversion efficiency () reaching 0.56%. Furthermore, all the devices fabricated with the benzothiophene molecules exhibit large open-circuit voltage (VOC) in the range between 0.67−0.98 V. This can be attributed to the more stabilized HOMO levels of the benzothiophene compounds. OPVs based on N2 and N3 have the smallest short–circuit current density (JSC) when the concentration of PCBM is ~80 wt%. In comparison, the JSC values of N4 and N5 increase as the blending ratio of PCBM increases. The experiments using tapping–mode atomic–force microscopy (AFM) were conducted to probe the surface morphologies of the active layers of N2 or N5 devices. The N2/PCBM films are very uniform, and the r.m.s. surface roughness (σ) values are 0.320, 0.266 and 0.212 nm for blends of 1:1, 1:2 and 1:4 weight ratios, respectively. In comparison, the N5/PCBM films have surface roughness of 0.387, 0.302 and 0.205 nm, respectively, for blends of 1:1, 1:2 and 1:4 weight ratios. They have higher surface roughness values compared to the N2/PCBM films.

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