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Keywords:

  • Light-emitting diodes, organic;
  • Molecular imprinting;
  • Thin films, polymer

Abstract

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 μm pixelated (800 ppi) molecular organic light emitting devices (OLEDs) based on aluminum tris(8-hydroxyquinoline) (Alq3) and fabrication of narrow channel (15 μm) 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 μm), 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.