AbstractOne of the main challenges to achieve high-performance bottom-contact transistors involves the organic/electrodes contacts. This study provides a simple approach to address the contact issue by incorporating an inducing layer prior to the organic semiconductor deposition. The molecules of the inducing layer nucleate into lamellar grains from the edge to the channel, resulting in a good morphological contact to the bottom electrodes. The following active layer maintains nearly layer-by-layer growth mode and yields uniformed terraced-like films both on the electrode edges and in the channels. With the inducing layer, pentacene thin-film bottom-contact transistors are obtained with a hole mobility exceeding 1 cm2 V−1 s−1.

A series of organic field-effect transistors (OFETs) with patterned ultra-thin films for NH3 detection are achieved via fast dip-coating. The morphology and packing structure of the ultra-thin films are greatly dependent on the surface energy of the substrates, geometry features of the patterned electrodes and evaporation atmosphere during the dip-coating process, which in turn results in a significant difference in the NH3 sensing properties. Based on the newly proposed mechanism, low-trap dielectric-semiconductor interfaces, a stripe-like morphology and an ultrathin film (as low as 2 nm) enable the OFET-based sensors to exhibit unprecedented sensitivity (∼160) with a short response/recovery time. The efficient (2 mm s−1), reliable, and scalable patterning strategy opens a new route for solution-processed OFET-based gas sensors.

The growth of organic semiconductor with controllable morphology is a crucial issue for achieving high-performance devices. Here we present the systematic study of the effect of the alkyl chain attached to the functional entity on controlling the growth of oriented microcrystals by dip-coating. Alkylated DTBDT-based molecules with variable chain lengths from n-butyl to n-dodecyl formed into one-dimensional micro- or nanostripe crystals at different pulling speeds. The alignment and ordering are significantly varied with alkyl chain length, as is the transistor performance. Highly uniform oriented and higher-molecular-order crystalline stripes with improved field-effect mobility can be achieved with an alkyl-chain length of around 6. We attribute this effect to the alkyl-chain-length-dependent packing, solubility, and self-assembly behavior.

•Fast dip-coating was firstly used to fabricate patterned organic transistors.•Ultrathin oriented microstripes were obtained on hydrophobic surfaces.•Area-selective behaviour of organic films can be finely controlled.•Patterned transistor exhibit reasonable field-effect characteristics.Oriented organic field-effect transistor (OFET) stripe arrays on hydrophobic substrates were fabricated by fast dip-coating technique. The addressable growth was achieved by decreasing surface energy of the channel areas with respect to the electrodes via hydrophobic treatment. The higher surface energy of the electrodes allows solution to adhere and then organic semiconductors nucleate and bridge the channels after evaporation of the solvent. Area-selective behaviour can be controlled by adjusting surface property of transistor channel, geometry features of the gold electrodes, pulling speed and evaporation atmosphere. The mechanism behind is the competition between receding of the solution and evaporating of the solvent that generate the organic semiconductor films on the substrate. The patterned bottom-contact transistor arrays exhibit carrier mobility of 2.0 × 10−3 cm2 V−1 s−1, while no field-effect characteristics can be detected for bottom-contact arrays without hydrophobic treatment. Such reliable, fast and solution-based patterned OFET arrays are highly desirable for large-scale and low-cost production.