Oligothiophene-Functionalized Truxene: Star-Shaped Compounds for Organic Field-Effect Transistors

Abstract

Organic field‐effect transistors (OFETs) based on oligothiophene‐functionalized truxene derivatives have been fabricated for use as novel star‐shaped organic semiconductors in solution‐processible organic electronics. The electronic and optical properties of compounds 1–3, with increasing numbers of thiophene rings at each of the three branches, have been investigated using scanning electron microscopy (SEM), X‐ray diffraction measurements, and ultraviolet–visible (UV‐vis) and photoluminescence spectroscopies. The results show that with a stepwise increase of the thiophene rings at every branch, a transition from a polycrystalline to an amorphous state is observed. The characteristics of compounds 1, 2, and 3 used for OFETs exhibit a significant difference. The mobility depends greatly on the morphology in the solid state, and decreases in going from 1 to 3. Mobilities up to 1.03 × 10–3 cm2 V–1 s–1 and an on/off ratio of about 103 for compound 1 have been achieved; these are the highest values for star‐shaped organic semiconductors used for OFETs so far. All the results demonstrate that the truxene core of the oligothiophene‐functionalized truxene derivatives not only extends the π‐delocalized system, but also leads to high mobilities for the compounds.

π-Conjugated molecules with fused rings for organic field-effect transistors: design, synthesis and applications

“…In spite of the high mobility, tetrathiafulvalene compounds also showed some poor OFET characteristics, such as large off-current at zero gate voltage VG, low on/off ratio and non-saturating behavior. For example, high mobility but poor stability were obtained with DB-TTF (37), dinaphtho-TTF (38), DT-TTF (39) and the linear benzene-fused bis(TTF) (40). 26 It has been found that a decrease in the electron donating properties is necessary in order to enhance the air stability of TTF derivatives.…”

Electroactive C3symmetric discotic liquid-crystalline triindoles

“…This C 3 -symmetric molecule can be considered as an extended p-system in which three carbazole units are sharing an aromatic ring. Surprisingly, while its all-carbon counterpart truxene has been extensively investigated for the construction of extended hydrocarbons, 7 electro-optical devices 8 or liquid crystals, 9 the triindole has been very little studied. 10 In this paper we investigate the electron-rich triindole platform as a novel redox active discotic core.…”

Progresses in organic field-effect transistors and molecular electronics

“…We cooperated with Prof. Jian Pei at Peking University and synthesized star shaped thiophene derivatives( Fig. 3(8)) [32] , the mobility reaches 1.03×10 -3 cm 2 /V s. Recently, we further synthesized pyrene based butterfly shaped molecules and used them as organic field active layers (Fig. 3(9)), the mobility of the device is 3.7 ×10 -3 cm 2 /V s [43] .…”

“…Fig3. Modified organic field effect materials (7) asymmetrically substituted phthalocyanine [38] (8)Star shaped [32] and (9)butterfly shaped [43] organic semiconducing compounds 8 …”

“…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.…”