Syntheses, Morphologies, and Applications of Carbazole-Thiophene Conjugated Materials for Solution-Processable Organic Field-Effect Transistors
Date Issued
2014
Date
2014
Author(s)
Chang, Gung-Pei
Abstract
In this thesis, three interrelated systems of solution-processable organic filed-effect transistors (OFETs) were developed from molecular design of organic semiconducting materials to their corresponding deposition techniques. The building blocks of the organic semiconductors were all based on “carbazole” and “thiophene”.
Before fabricating OFET devices, the thermal, optical, and electrochemical properties of the studied materials were fully characterized with thermogravimetric analysis, differential scanning calorimetry, ultraviolet-visible spectroscopy, and cyclic voltammetry to realize the relationships of the structure to the properties. The thin film morphologies of the studied materials as the OFET active layers were also investigated with polarizing optical microscopy, atomic force microscopy, and X-ray diffraction to realize the structural relationships to OFET performances.
In chapter 2, a series of constant conjugated backbone (carbazole-bithiophene-carbazole, CxCzT2) oligomers were prepared with various n-alkyl chain lengths. The highest FET mobility of them was in the order of 1.2×10-1 cm2V-1s-1 via solution-casting deposition. In chapter 3, an inverse conjugated backbone based on bithiophene-carbazole-bithiophene (DH4T-Cz) was prepared and yield the highest FET mobilityin the order of 5×10-1 cm2V-1S-1 via dip-coating deposition. The thin film morphologies of DH4T-Cz can be controlled via different solution deposition techniques, and yielded different OFET performances. In chapter 4, two polystyrene-derivative polymers with grafting π-conjugated moieties (bicarbazole, PStCz2; carbazole-bithiophene-carbazole, PStCzT2Cz) were prepared as a novel class of polymeric semiconductor for OFET. The highest FET mobility was in the order of 1.1×10-3 cm2V-1s-1 via spin-coating deposition.
These three interrelated developments brought economical and low-cost concepts to the molecular design of organic semiconducting materials, solution-process of OFET active layers, and high performances of OFET devices.
Subjects
有機場效電晶體
可溶液製程
咔唑
噻吩
高場效遷移率
Type
thesis
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