Advanced Functional Materials

Cover image for Vol. 27 Issue 28

17_15/2007Cover Picture: High Definition Digital Fabrication of Active Organic Devices by Molecular Jet Printing (Adv. Funct. Mater. 15/2007)

A new method for direct patterning of organic optoelectronic/electronic devices using a reconfigurable and scalable printing method is reported by Vladimir Bulovic and co-workers on p. 2722. The printing technique is applied to the fabrication of high-resolution printed organic light emitting devices (OLEDs) and organic field effect transistors (OFETs). Remarkably, the final print-deposited films are evaporated onto the substrate (rather than solvent printed), giving high-quality, solvent-free, molecularly flat structures that match the performance of comparable high-performance unpatterned films.

We introduce a high resolution molecular jet (MoJet) printing technique for vacuum deposition of evaporated thin films and apply it to fabrication of 30 &mgr;m pixelated (800 ppi) molecular organic light emitting devices (OLEDs) based on aluminum tris(8-hydroxyquinoline) (Alq3) and fabrication of narrow channel (15 &mgr;m) organic field effect transistors (OFETs) with pentacene channel and silver contacts. Patterned printing of both organic and metal films is demonstrated, with the operating properties of MoJet-printed OLEDs and OFETs shown to be comparable to the performance of devices fabricated by conventional evaporative deposition through a metal stencil. We show that the MoJet printing technique is reconfigurable for digital fabrication of arbitrary patterns with multiple material sets and high print accuracy (of better than 5 &mgr;m), and scalable to fabrication on large area substrates. Analogous to the concept of “drop-on-demand” in Inkjet printing technology, MoJet printing is a “flux-on-demand” process and we show it capable of fabricating multi-layer stacked film structures, as needed for engineered organic devices.

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