A Highly π-Stacked Organic Semiconductor for Field-Effect Transistors Based on Linearly Condensed Pentathienoacene

Abstract

We present the synthesis and characterization of a fused-ring compound, dithieno[2,3-d:2',3'-d']thieno[3,2-b:4,5-b']dithiophene (pentathienoacene, PTA). In contrast to pentacene, PTA has a larger band gap than most semiconductors used in organic field-effect transistors (OFETs) and therefore is expected to be stable in air. The large pi-conjugated and planar molecular structure of PTA would also form higher molecular orders that are conductive for carrier transport. X-ray diffraction and atomic force microscopy experiments on its films show that the molecules stack in layers with their long axis upright from the surface. X-ray photoelectron spectroscopy suggests that there are no chemical bonds at the PTA/Au interface. OFETs based on the PTA have been constructed, and their performances as p-type semiconductors are also presented. A high mobility of 0.045 cm(2)/V s and an on/off ratio of 10(3) for a PTA OFET have been achieved, demonstrating the potential of PTA for application in future organic electronics.

Semiconducting Organic Molecular Materials

“…It was initially applied in OFETs by Xiao et al [13] in 2005. In comparison to pentacene, molecules of its thiophene analogue 5 interact together more tightly through additional intermolecular S-S contact in solid state, so that a slipped π -stacking model with a short distance of 3.52Åwas demonstrated.…”

Progresses in organic field-effect transistors and molecular electronics

“…We have synthesized tens of organic materials and their derivatives, such as asymmetrically substituted phthalocyanine, ladder tetraazapentacenes [29] , cyclo pyrroles [30,31] , condensed pentathienoacene [32,33] . We also fabricated organic field-effect transistors [34] and nano electron devices [35] based on these materials.…”

“…Thus, substitutional pentacene like molecules are expected to have superior field effect performances. (1) ladder tetraazapentacenes [29] (2) pentathienoacene [33] (3) dithieno[3,2-b:2′,3′-d]thiophene [36] We synthesized ladder tetraazapentacenes semiconductors( Fig.1 (1)) with mobility up to 0.02 cm 2 /V s [29] . Recently, another pentacene like semiconducting compound pentathienoacene 6 was synthesized as shown in Fig.1 (2) by cooperation with Prof. Jingui Qin's group at Wuhan…”

“…The energy gap Eg of pentathienoacene is 3.29eV（for pentacene it's only 1.85 eV), the decomposition temperature is 272℃ and the OFET mobility is 0.045 cm 2 /V s, indicating pentathienoacene is a very promising material for high performance transistors with excellent stability [33] . We further fabricated transistors based on derivatives of dithieno[3,2-b:2′,3′-d]thiophene( Fig.1(3)).…”

Thiophene–phenylene/naphthalene‐based step‐ladder copolymers

“…For example, in addition to the original methylene bridges, ethane, or carbonyl bridges have been described as well as heteroatom bridges containing nitrogen or sulfur atoms, respectively. [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] Within this contribution the synthesis of a series of novel, partly rigidified, thiophene-phenylene-thiophene, and thiophene-naphthylene-thiophene-based step-ladder copolymers is described. These alternating copolymers contain a central ladder-type building block that was synthesized in a ring closure reaction similar to the LPPP synthesis that was combined with oligothiophene segments of different length (Fig.…”