Organic semiconductor devices OFETs

Due to the great potential applications and the widespread interests of OFETs, several review articles with emphasis on different aspects of OFETs have been published [8-13], However, despite the extensive studies and increasing research interests in phthalocyanine as well as porphyrin semiconductors, there is still no review article that systematically generalizes the research achievements in the field of tetrapyrrole organic semiconductors for OFETs. Thus, the present contribution should interest scientists in both industrial and theoretical fields. The main contents of this chapter is as follows Firstly, some basic introduction of the structure and characteristics of OFET is provided then theoretical factors that influence the performance of OFET devices is discussed finally, the progress in phthalocyanine-based OFETs in the order of p-type, n-type, and ambipolar semiconductors is summarized. 

The development of microelectronics cannot be envisaged without a comprehensive modeling of the devices. The modeling of OFETs is currently hampered by several features. First, charge transport in organic semiconductors is still not completely understood. The situation is clear at both ends of the scale. In high mobility materials (//>IOcnr V-1 s l), transport occurs within delocalized levels when temperature... 

As a class of n-type organic semiconductors, PBI derivatives have received considerable attention for a variety of applications [312, 313], for example, for organic or polymer light-emitting diodes (OLEDs and PLEDs) [314, 315], thin-film organic field-effect transistors (OFETs) [316, 317], solar cells [318, 319], and liquid crystals [320]. They are also interesting candidates for single-molecule device applications, such as sensors [321], molecular wires [322], or transistors [141]. 

The field known as organic or plastic electronics is centered on field effect transistor (FET)-based circuits mounted on large-area and/or flexible substrates. When the semiconductor is organic, the device is referred to as an organic field-effect transistor (OFET). Work on OFET has been extensively reviewed, most notably and comprehensively in Chemistry of Materials and Journal of Materials Research special issues, to which the one of us has contributed three articles [1-3]. 

Figure 4 shows the molecular structures of the monomeric phthalocyanines used as the active layer of p-type OFET devices, and Table 1 organizes the performance of these phthalocyanine-based OFETs. As can be seen, unsubstituted metal-free phthalocyanine and its metal complexes, axial substituted metal phthalocyaines, and peripheral tetra-substituted phthalocyanines all can work as p-type semiconductors for OFET devices. Most of the semiconductors composed of peripheral unsubstituted and axial substituted phthalocyanine derivatives are prepared through vacuum deposition method with a few exceptions being made of corresponding single... 

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