Improvements in organic electronic materials have led to novel device applications, ranging from large-area flexible displays to lightweight plastic electronics. Progress on these applications would benefit from development of low-cost fabrication techniques for organic semiconductors. In this review, several fabrication processes based on adhesion force (i.e. van der Waals forces, thiol–metal reactions, and cold welding) are introduced. These patterning techniques are dry patterning techniques, i.e., the electronic materials are patterned from the raised regions of molds onto a substrate directly by additive or subtractive patterning methods. Patterning of organic small molecule, polymer thin films and metal electrodes by adhesive lithography is demonstrated. The operating properties of patterned organic light-emitting diodes (OLEDs) and organic thin film transistors (OTFTs) are comparable with the performance of devices fabricated by conventional evaporation deposition methods.

Small molecular organic light-emitting diodes (SMOLEDs) were fabricated with an ink-jet printed film of 2-(t-butyl)-9,10-bis (20-naphthyl) anthracene (TBADN) doped with 4,4′-bis[2-{4-(N,N-diphenylamino)phenyl vinyl] (DPAVBi) as emitting layer. Dewetting behavior of ink-jet printed TBADN/DPAVBi solutions were restrained by adding cyclohexylbenzene or α-chloronaphthalene to the main solvent chlorobenzene. The high boiling point and high viscosity of cyclohexylbenzene and α-chloronaphthalene has increased the thickness of liquid films and the viscosity, which restrained the dewetting from thermodynamics and kinetics aspect. Uniform TBADN/DPAVBi films obtained by ink-jet printing from chlorobenzene/cyclohexylbenzene solution have been used in the fabrication of matrix display of SMOLEDs. The OLEDs has a turn-on voltage of 5.5 V, the maximum luminance of 289 cd/m2 and the maximum current efficiency of 0.71 cd/A.Graphical abstractResearch highlights► Uniform and pinhole free TBADN/DPAVBi films were deposited by inkjet printing. ► High boiling point and high viscosity solvents improved film forming property. ► Dewetting of TBADN/DPAVBi films restrained from thermodynamics and kinetics aspect. ► Inkjet printed TBADN/DPAVBi films were used to fabricate electroluminescent devices.

This paper reports a facile one-step method for making undercut structures by dewetting of poly(methyl methacrylate) (PMMA) chloroform solution on an ice/water mold. The ice mold is prepared by filling the microchannels with water (micromolding in capillaries (MIMIC) method) and then freezing. The curving surface of water mold stripes and the trapezoidal structure of ice mold stripes work as complementary structures devoted to the formation of undercut structures. The undercut structures with angles of 60° and 40° are obtained, which is determined by the states of ice or water mold. Meanwhile, if the solution concentration is increased, patterned polymer films with different configurations of undercut structures or microchannels would be gained.