| 摘要: | 有機薄膜上分子的空間結構和排列位向會影響分子與載體之間的電荷傳導，進而影響到有機薄膜電晶體(OTFTs)的性能。因此我們利用掃描式電子穿隧顯微鏡探討併環噻吩衍生物在金(111)電極上的吸附結構。
首先，探討TTE (4,4-dicyclopenta[2,1-b:3,4-b]-dithiophene)修飾於金(111)電極上的吸附行為及結構。因為TTE分子本身的特性，意外的發現前手性分子的吸附行為，TTE吸附於電極表面後形成R(S)光學異構物。對於TTE而言，在0.25 V電位下，吸附層形成(7 X 14)整齊的鋸齒狀結構排列，其覆蓋度為0.061。經高解像結構增加對比度後發現，TTE分子具有特定方位的亮點可以分辨R(S) - TTE分子，也顯示分子形成RSR或SRS的排列順序，顯示分子間可能存在S…S的作用力。在- 0.15 V電位下，TTE分子吸附整齊的(2√3 X 3√3)結構於重排載體上，且TTE分子為單一光學異構物的吸附。經過電位調控確定其結構變化為可逆，推測電位對於相轉變的影響力大於載體結構。低覆蓋度的TTE修飾於金(111)上，顯示TTE以分子鍊的方式吸附於重排結構上，且從高解像圖判斷分子以硫端用edge-on的方式吸附於電極表面，代表TTE分子和載體之間靠著凡得瓦力吸引，以及分子間靠著π…π吸引力排列。
利用金(100)重排結構至(1 X 1)會擠出約20 %的金原子的特徵，調控至正電位增加表面粗糙度後在添加1 mM的鹵素離子探討對於金原子移動性的影響。發現氯、溴、碘離子在正電位下皆可以驅動金的移動性，推測正電位下鹵素離子與金原子形成錯合物提高金的移動能力，且金原子的移動方向遵循著載體方向。在原位的實驗觀察發現金錯合物除了表面的移動性外，還有部分的金錯合物溶解於電解液中。金(100)電極經過金原子劇烈移動後相較於佈滿(1 X 1)金島的狀態，表面粗糙度下降且變得更為平整，顯示鹵素離子對於金載體可做為平整劑。
;The spatial structure and orientation of the molecules on the organic film affect the charge conduction between the molecule and the carrier.This in turn affects the performance of organic thin film transistors (OTFTs). Therefore, we used a scanning tunneling microscope (STM) to investigate the adsorption structure of a cyclothiophene derivative on a gold (111) electrode.
Firstly, the adsorption behavior and structure of TTE (4,4-dicyclopenta [2,1-b:3,4-b] -dithiophene) modified on Au(111) electrode were investigated. Because of the characteristics of the TTE molecule itself, the adsorption behavior of the prochiral molecule was unexpectedly discovered, and the TTE adsorbed on the surface of the electrode to form an R(S) optical isomer. For TTE, at a potential of 0.25 V, the adsorption layer formed a (7 X 14) zigzag structure with a coverage of 0.061. After increasing the contrast by high resolution, it is found that the bright spot of the TTE molecule with a specific orientation can distinguish the R(S)-TTE molecule, and also shows the order in which the molecules form the RSR or SRS, indicating that there may be a force of S...S between the molecules. At a potential of -0.15 V, the TTE molecule adsorbs a neat (2√3 X 3√3) structure on the reconstruction structure, and the TTE molecule is a single optical isomer. After the potential regulation is determined, the structural change is reversible, and the influence of the potential on the phase transition is estimated to be greater than the carrier structure. The low-coverage TTE is modified on Au(111), which shows that the TTE is adsorbed on the reconstruction structure, and the high-resolution image is judged to adsorb the molecule on the surface of the electrode with the sulfur end in an edge-on manner. The electrostatic attraction of S...Au between the TTE molecule and the carrier, and the attraction between the molecules by π...π attraction.
Using the Au(100) reconstruction structure to (1 X 1) will extrude about 20% of the gold atoms. After controlling the positive potential to increase the surface roughness, add 1 mM of halogen ions at the positive potential to investigate the gold atom. The impact of mobility. It is found that chloride, bromine and iodine ions can drive the mobility of gold at a positive potential. It is speculated that the halide ion forms a complex with the gold atom at a positive potential to improve the mobility of gold, and the moving direction of the gold atom follows the carrier direction. In situ experiments have revealed that in addition to the surface mobility of the gold complex, a portion of the gold complex is dissolved in the electrolyte. After the Au(100) electrode is vigorously moved by the gold atom, the surface roughness is reduced and becomes flatter than that of the (1 X 1) gold island. It is shown that the halogen ion can be used as a leveling agent for the gold carrier. |
