The perfect molecular order, the absence of grain boundaries and the minimized concentration of charge traps in organic single crystals make them extremely promising for the study of intrinsic properties of organic materials and fabrication of high performance devices and circuits. It also provides the opportunity for revealing the relationship between the microscopic molecular packing and the macroscopic charge transport of the organic semiconductor materials. Due to the weak intermolecular interaction of Van der Waals' force, organic single crystals mostly exist as micro- and nano-crystals. Currently, various material systems have been applied in the fabrication of micro- and nano-crystal field-effect transistors (FETs) and these devices have enabled both the screen of high-performance materials and a better understanding of the charge transport physics of organic semiconductors. Here the structure and operation modes of the organic single crystal field-effect transistors (OSCFETs), growth methods, characterization methods and device fabrication methods of organic micro- and nano-crystals are introduced respectively. Moreover, the progress made during the past three years on organic micro- and nano-cyrstal semiconductor materials and devices are summarized. Finally, the hot topics, tendency and challenges of the organic micro- and nano-cyrstal studies are discussed as well. Contents
1 Introduction
2 Structures and operation mechanism of organic single crystal field-effect transistors
3 Crystallization methods
3.1 Gas phase methods
3.2 Liquid phase methods
4 Characterization methods
4.1 X-ray diffraction
4.2 Atomic force microscope
4.3 Scanning electron microscope
4.4 Transmission electron microscope and selected area electron diffraction
5 Fabrication methods
5.1 Direct fabrication method
5.2 Lamination method
5.3 Mask method
5.4 Au film gluing method
5.5 Drop-casting method
6 Central issues and tendency of present researches
6.1 Design and synthesis of high performance materials
6.2 Controlled growth of micro- and nano-crystals
6.3 Production of large area crystalline films
6.4 Multifunction of organic micro- and nano-crystals
6.5 Tendency of international cooperation and interdisciplinary development
7 Challenges of micro- and nano-crystal research
7.1 Transport theory of charge carriers in organic micro- and nano-crystals
7.2 Development of air-stable n type micro- and nano-crystal materials
7.3 Standardization of fabrication methods
7.4 Development of high performance and large scale crystal circuits
8 Conclusion and outlook