In this study, we report a contact printing technique that uses polyurethane-acrylate (PUA) polymers as the printing stamps to pattern electroluminescent layers of organic light emitting diodes (OLEDs). We demonstrate that electroluminescent thin films can be printed with high uniformity and resolution. We also show that the performance of the printed devices can be improved via postprinting thermal annealing, and that the external quantum efficiency of the printed devices is comparable with the efficiency of the vacuum-deposited OLEDs. Our results suggest that the PUA-based contact printing can be used as an alternative to the traditional shadow mask deposition, permitting manufacturing of OLED displays with the resolution up to the diffraction limit of visible-light emission.

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Polyurethane–acrylate (PUA) materials were used as printing stamps in the high-resolution contact printing of organic molecules and organic thin films to show that PUA-based printing can be used as a simple alternative to a kinetically modulated PDMS stamping.

Diverse thiol esters were synthesized in good to excellent yields (76-99%) by reactions of thiophenol, benzyl mercaptan, ethyl mercaptoacetate, and mercaptoacetic acid with N-acylbenzotriazoles under mild conditions. These results demonstrate the utility of N-acylbenzotriazoles as mild S-acylating agents, especially when the corresponding acid chlorides are not readily available.

We report a new inkless catalytic µCP technique that achieves accurate, fast, and complete pattern reproduction on SAMs of Boc-and TBS-protected thiols immobilized on gold using a polyurethane-acrylate stamp functionalized with covalently bound sulfonic acids. Pattern transfer is complete at room temperature just after one minute of contact and renders sub-200 nm size structures of chemically differentiated SAMs.KEYWORDS Microcontact printing, soft lithography, catalytic lithography M icrocontact printing (µCP) was first introduced by Whitesides and co-workers in 1993 as a new flexographic technique for patterning self-assembled monolayers (SAMs) on metal surfaces. 1-9 It represents the prototypical embodiment of a family of related patterning techniques, collectively termed soft lithography, that make use of conformal contact between a substrate and a flexible stamp as a means of pattern reproduction. 5,8,10 Since its inception, µCP has become a highly successful lowcost printing method that efficiently reproduces high-resolution patterns over large surface areas. During the past 20 years µCP has been successfully utilized to pattern small organic compounds, inorganic substances, biomolecules, and even living cells on a variety of hard materials. Recently, µCP has been used for the fabrication of organic thin film transistors, where it is utilized as an inkjet printing alternative to pattern conductive organic polymers on both hard and flexible substrates. [11][12][13] Although traditional µCP is capable of reproducing features with reasonably high spatial resolution, structures smaller than 300 nm significantly limit the number of possible ink-substrate systems and demand precise control over stamping time, the amount of ink applied, the printing force, and the shape and definition of the stamp pattern. 6,14 In routine applications, several shortcomings of traditional µCP, especially distortion and deformation of the elastomeric stamp, 15,16 and more importantly, spreading of molecular inks by both gas diffusion and diffusive wetting, 17 preclude accurate replication of submicrometer features. Several approaches to minimize ink spreading have recently been developed, through substitution of liquid inks by various solid analogues, such as polymers and metal thin films, [18][19][20][21][22] or by avoiding the use of chemical inks completely and utilizing instead a catalytic reaction between the elastomeric stamp and substrate. [23][24][25][26] The first example of catalytic microcontact printing was reported in 2003 by Reinhoudt et al., who used an oxidized PDMS stamp to deprotect TMS-and TBS-modified SAMs on gold. The method clearly demonstrated the ability of an acidic stamp to deprotect immobilized silyl ethers and reproduce micrometersize features with sub-100 nm edge resolution, although the approach achieved only partial cleavage and required a new stamp for each pattern transfer. 23 Recently, we reported two inkless µCP methods that employ catalysts bound to polymeric stamps to reproduce patterns...