High-Performance Field-Effect Transistor Based on Dibenzo[d,d' ]thieno[3,2-6;4,5-b']dithiophene, an Easily Synthesized Semiconductor with High Ionization Potential

摘要

Organic field-effect transistors (OFETs) have attracted much attention as an alternative to conventional silicon-based transistors because they can be potentially fabricated at low cost, in large areas, and on flexible substrates. To realize these advantages of OFETs in commercial application, the performance of OFET devices, such as mobility and stability, should be comparable with that of amorphous hydrogenated silicon. Currently, the best performing p-type organic thin film FET material is pentacene, with mobility above 1.0 cm~2V~(-1)s~(-1) and on/off ratio larger than 10~6. However, pentacene is unstable and degrades rapidly in ambient conditions, because it is subject to photo-induced decomposition, presumably forming transannular endoperoxide or dimeric Diels-Alder ad-ducts. In order to improve the stability, several pentacene analogues, pentathienoacene (PTA), tetraceno[2,3-b]thio-phene (TCT) and anthradithiophene (ADT)' were synthesized. These materials indeed showed higher stability than that of pentacene and pretty good FET performance (mobility up to ca. 0.4 cm~2V~(-1)s~(-1) and on/off ratio up to 10~6). However, most of these materials suffered from a tedious synthesis and/ or bothersome purification processes, and their stabilities were still far from those needed for practical applications.