Programmed Design of Highly Crystalline Organic Semiconductor Patterns with Uniaxial Alignment via Blade Coating for High-Performance Organic Field-Effect Transistors

Abstract

A solution-printing technique that enables the patterning and aligning of organic semiconducting crystals is necessary for their practical application. Here, we report the facile growth of 6,13-bis­(triisopropylsilylethynyl) pentacene (TIPS-PEN) semiconducting crystal patterns via a novel blade-coating technique. Defining low/high shearing-speed regions alternatively in a programmed manner enables the growth of TIPS-PEN crystals in low-speed regions and their patterning in high-speed regions. Various crystal-analysis tools, including polarized UV–vis absorption spectroscopy, grazing-incidence wide-angle X-ray scattering, and near-edge X-ray absorption fine structure, reveal that a crystal grown at an optimum shearing speed is highly oriented along the shearing direction with high crystallinity, and its molecules have a more edge-on orientation for efficient lateral-charge transport. As a result, organic field-effect transistors comprised of these crystals show a high field-effect mobility of up to 1.74 cm2/(V s). In addition, various crystal patterns can be created by simply changing the programming parameters, suggesting the broad utility of the crystal patterns and printing technique.

Stencil mask defined doctor blade printing of organic single crystal arrays for high-performance organic field-effect transistors

“…17,18 Single crystal OSC arrays would be ideal for high-performance organic integrated circuits with excellent uniformity and reproducibility. [19][20][21][22] However, challenges remain to fabricate organic single crystal arrays with highresolution by printing methods. [23][24][25] Unlike inorganic semiconductors, conventional photolithography processes may not be applicable for OSCs, because the organic semiconductor would be damaged by processing chemicals or high temperature.…”

“…17,34,35 In addition, multiple grain boundaries are presented in organic thin films, which may increase the device-to-device variation. [39][40][41] In this work, we demonstrated a method to realize solution processed organic single crystal arrays with spatial resolution down to 30 mm, which is smaller than the average droplet size of conventional inkjet printing. A large-area continuous organic single crystalline thin film is first fabricated by using solution shearing, and then covered by a patterned aqueous resist deposited by stencil mask defined doctor blade printing.…”

Directionally Patterned Large-Area Poly(3-hexylthiophene) Field-Effect Transistors via Flow-Blade Printing Method Using Coffee-Ring Effect: Uniform Performance Regardless of Pattern Fabrication Condition and Applications

“…The NEXAFS analysis can be used to measure the average conformation of molecules in various bonding including πorbital, single bond, and double bond by detecting the X-ray absorption. 26,44 The azimuthal average tilting angle (α) of the conjugated plane was extracted by plotting the intensity (I) of the corresponding resonance with the following equation: 45…”

Heteroalkyl‐Substitution in Molecular Organic Semiconductors: Chalcogen Effect on Crystallography, Conformational Lock, and Charge Transport

“…Densely packed microcrystals can be found for 1 and 1B films, which can thus create continuous charge transport pathways, however, 1C films exhibit large gaps between microsized domains and the step height (or thickness) of the crystal is as high as 75 nm (see inset of Figure S12c, Supporting Information), which may act as charge trap as seen for other highly textured, but disconnected, semiconductor films integrated in OFETs. [110,111] Interestingly, the film morphologies of both compounds 2 and 3 are also nonoptimal and unfavorable for high-performance OFETs. Thus, the solution-sheared 2 film appears amorphous and smooth in the continuous areas with scattered isotropic holes (Figure 7d).…”