Influence of SiO2 surface energy on the performance of organic field effect transistors based on highly oriented, zone-cast layers of a tetrathiafulvalene derivative

Abstract

In this paper we present that the surface energy of silicon dioxide employed as the dielectric in bottom gate organic field effect transistors has large impact on the device performance. By the use of the zone-casting simple solution processing technique, we ensured reproducibility of active layer preparation confirmed by the atomic force microscopy and x-ray diffraction that showed high crystalline quality. Electrical measurements revealed that charge carrier mobility based on highly ordered zone-cast tetrakis-(octadecylthio)-tetrathiafulvalene layer was increased 30 times to 0.2 cm2/V s, when dielectric surface energy decreased from 51.8 to 40.1 mN/m.

Interfacial Heterogeneity of Surface Energy in Organic Field‐Effect Transistors

“…[16][17][18][19][20][21][22][23] Wu has suggested [ 37 ] that the variation in surface energy as a function of MW stems from the different surface energies of chain ends and repeat units (see Equation 1 and Equation 2). The chain ends of PS have been reported to have a lower surface energy than the repeat units (e.g., the surface energy of the -CH-(phenyl ring edge) is reported as about 45.1 mN m − 1, and the -CH 3 is of 23.0-30.5 mN m − 1 ).…”

“…[16][17][18] In previous literature, the surface energy is usually calculated by measurements of contact angles at different points on the surface. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] However contact angle measurements is a 'statistic-average' method that can only indicate differences at a millimeter level, and obviously cannot describe whether or not the interfacial state is homogeneous on the nanometer scale. [16][17][18][19][20][21][22][23] The latter is crucial, because the surface energy of the dielectric mainly infl uences the performances of OFETs at the interface on just such a nanometer scale.…”

Organic field-effect transistors

“…In addition to the conventional in− [27]. Average charge carrier mobility was 30 times increased as a result of proper treat− ing.…”

Short‐Channel Solution‐Processed Organic Semiconductor Transistors and their Application in High‐Speed Organic Complementary Circuits and Organic Rectifiers

“…µ eff is the effective carrier mobility of an organic semiconductor, including the effects of contact resistance, C para is the parasitic gate capacitance, and c i WL represents the channel capacitance. [9][10][11][12] Although many studies have been carried out to investigate solution-processable organic fi eld-effect transistors (OFETs), most of these studies utilized polycrystalline semiconductor fi lms in which the crystals were randomly oriented. From Equation ( 1) , it is clear that short-channel high-mobility transistors are strongly important to raise up the maximum operational speed of organic transistors.…”

“…In the saturation regime, V D is replaced by the gate voltage V G . [9][10][11][12] Although many studies have been carried out to investigate solution-processable organic fi eld-effect transistors (OFETs), most of these studies utilized polycrystalline semiconductor fi lms in which the crystals were randomly oriented. To realize a high fi eld-effect mobility in a short-channel device, it is crucial to reduce the contact resistance between the organic materials and the contact electrodes, which has been a challenging issue in organic transistors.…”