本論文主要著重於製作高效能的有機薄膜場效電晶體(OTFTs)，可溶性有機半導體薄膜分別藉由退火與摻雜處理，並探討其結晶性質與各介面對有機薄膜場效電晶體效能的影響，期待能製作高效能元件。挑選的可溶性p型有機半導體分子為2,8-difluoro-5,11-bis- (triethylsilylethynyl) anthradithiophene (diF-TESADT)，實驗分成二個部分：
第一部分著重於利用退火處理(post annealing)改善有機薄膜結晶性質。不同退火條件處理的薄膜分別藉由原子力顯微鏡(Atomic Force Microscope，AFM)、X光繞射(X-Ray Diffraction，XRD)、掠角入射X光繞射(Grazing Incidence X-Ray Diffraction)、與近緣X光吸收細微結構(Near-Edge X-Ray Absorption Fine Structure，NEXAFS)觀察其表面形貌、結構、結晶性變化。旋轉塗佈完成後的薄膜的形貌呈現稻穗狀分佈。掠角入射X光繞射清楚顯示此薄膜是由二種不同傾角的晶粒所構成。一是以(001)面法線齊一的排列，另一種是以(111)面法線齊一的排列。此混和排列的薄膜所製作的電晶體其載子遷移率不高，約在10-3 cm2V-1s-1左右，最高為0.37 cm2V-1s-1。經溶劑蒸氣再結晶輔以加熱退火處理後的diF-TESADT薄膜的成長形貌由原本稻穗狀變成大片連續層狀結構，薄膜平面方向進行大規模結構重整，從(111)轉變成適於晶體延展與有利載子跳度的(001)面齊一法線的排列形式。同時也提升了沿著法線方向的結晶性。因而使元件載子遷移率□平均值提升至1.39 cm2V-1s-1，最高至2.7 cm2V-1s-1。
第二部分則利用具有拉電子特性的有機分子2,3,5,6-tetrafluoro-7,7,8,8-tetra cyanoquinodimethane (F4-TCNQ)作為摻雜物(dopant)，藉以改善以diF-TESADT為主的有機薄膜場效電晶體之介面偶極效應，進而優化電性表現。藉由紫外光光電子能譜(Ultraviolet Photoemission Spectroscopy，UPS)、X光光電子能譜(X-Ray Photoemission Spectroscopy，XPS)、NEXAFS、AFM討論能階變化、形貌、電性表現的關係。以F4-TCNQ摻雜的diF-TESADT薄膜作為有效傳輸層(active layer)製作成有機薄膜場效電晶體(OTFTs)，特定的摻雜比例可大幅降低臨界電壓(threshold voltage，VTH)，推測F4-TCNQ的拉電子特性對有機場效電晶體的介面偶極有中和的效果，使VTH由21.3 V降至1.47 V；但過量的F4-TCNQ則會扮演雜質，阻礙晶體的延展。

In the thesis, we detail the progress made in improving the thin films of 2,8-difluoro-5,11-bis (triethylsilylethynyl) anthradithiophene (diF-TESADT) for high mobility OFET application.
In part (I) experiment, different post-annealing methods were used to improve the organic thin film structure. Morphology, structure, and crystallinity of diF-TESADT films are of particular concern and investigated by combined techniques of atomic force microscopy (AFM), grazing-incidence x-ray diffraction (GIXD), and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy. The diF-TESADT films produced from spin-coating exhibit wheat-like features and GIXD data reveal the presence of both (001)- and (111)-oriented crystallites on the surface. Despite the mixed orientation, as-grown diF-TESADT can still produce OFET with a best mobility of 0.37 cm2V-1 s-1. Improvement in film quality is achieved by employing solvent annealing followed by thermal annealing. The resultant diF-TESADT films exhibit smooth, plate-like features, and GIXD data show a complete structural transformation to (001)-oriented crystallite, a much favored structure for efficient hole transport. The highest OFET mobility reaches 2.70 cm-1V-1s-1, with the median mobility averaged over 15 devices equal to 1.4 cm-1V-1s-1.
In part (II) experiment, we used the strong electron-acceptor 2,3,5,6-tetrafluoro- 7,7,8,8-tetracyanoquinodimethane (F4-TCNQ), as a dopant in diF-TESADT thin film to improve the charge transfer properties. We investigated how the energy levels of organic semiconducting thin films of diF-TESADT change with the F4-TCNQ dopant concentration with ultraviolet photoemission spectroscopy (UPS) and x-ray photoemission spectroscopy (XPS). The results showed that the shift the energy level of diF-TESADT -0.3 eV. The effect of solvent vapor annealing on the morphology and device performance of thin films was also investigated. When molar dopant ratio of reaches 0.37%, the unvanished plate-like features give a small degradation of mobility but the devices averaged threshold voltage shifts from 21.3 V to 1.47 V. We concluded the dramatic VTH variation is presumably due to the structure reorganization of thin film when post annealing. As a consequence, F4-TCNQ effectively neutralized the residual dipoles at the interface between semiconductor layer and the dielectric substrate.

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