Fabrication of high performance/highly functional field-effect transistor devices based on [6]phenacene thin films

Abstract

Field-effect transistors (FETs) based on [6]phenacene thin films were fabricated with SiO2 and parylene gate dielectrics. These FET devices exhibit field-effect mobility in the saturation regime as high as 7.4 cm(2) V(-1) s(-1), which is one of the highest reported values for organic thin-film FETs. The two- and four-probe mobilities in the linear regime display nearly similar values, suggesting negligible contact resistance at 300 K. FET characteristics were investigated using two-probe and four-probe measurement modes at 50-300 K. The two-probe mobility of the saturation regime can be explained by the multiple shallow trap and release model, while the intrinsic mobility obtained by the four-probe measurement in the linear regime is better explained by the phenomenon of transport with charge carrier scattering at low temperatures. The FET device fabricated with a parylene gate dielectric on polyethylene terephthalate possesses both transparency and flexibility, implying feasibility of practical application of [6]phenacene FETs in flexible/transparent electronics. N-channel FET characteristics were also achieved in the [6]phenacene thin-film FETs using metals that possess a small work function for use as source/drain electrodes.

Transistor application of alkyl-substituted picene

“…The < μ > value, 7(2) cm 2 V −1 s −1 , in a picene-(C 14 H 29 ) 2 thin film FET with SiO 2 gate dielectric was higher than those of thin-film FETs with picene (1.0–3.0 cm 2 V −1 s −1 )1314 and [7]phenacene (0.8 cm 2 V −1 s −1 )20, while comparable to that (7.4 cm 2 V −1 s −1 )19 of a [6]phenacene thin-film FET. Despite the absence of parallel planes stacked on the SiO 2 surface, the < μ > value is higher than that of thin-film FET with picene, suggesting a presence of other factor such as high overlap (transfer integral) between molecules in picene-(C 14 H 29 ) 2 thin film.…”

“…High-performance organic field-effect transistors (FETs) fabricated with various types of organic molecules have desirable characteristics such as light weight, mechanical flexibility, large area coverage, ease of design, and low-energy/low-cost fabrication12345678910111213141516171819202122232425262728. The highest field-effect mobility, μ , is presently 17.2 cm 2 V −1 s −1 in thin-film organic FETs29 and 94 cm 2 V −1 s −1 in single-crystal organic FETs22.…”

An Extended Phenacene-type Molecule, [8]Phenacene: Synthesis and Transistor Application

“…The highest μ values were achieved by [6]phenacene in a thin-film FET7, and for [7]phenacene in a single-crystal FET10. The μ value for the former FET reached 7.4 cm 2 V −1 s −1 , while that for the latter reached 6.7 cm 2 V −1 s −1 .…”

“…This molecule was stable in the dark but highly vulnerable to photolysis in solution. In contrast, phenacene-type molecules are known to be more stable than acene-type molecules, and show no degradation under ambient conditions, even in the light12345678910111213. This implies that phenacenes are more suitable for FET application than acenes.…”

“…Field effect transistors (FETs) using thin films or single crystals of phenacene-type molecules, which consist of a number of coplanar benzene rings fused into an extended W-shape configuration have shown excellent p-channel properties, with the field-effect mobility ( μ ) being greater than 1 cm 2 V −1 s −1 1234567891011. The highest μ values were achieved by [6]phenacene in a thin-film FET7, and for [7]phenacene in a single-crystal FET10.…”