…of PEDOT:PSS on barrier/foil for organic electronics applications
Authors : Dimitris Karnakis, Tim Stephens and Gregoire Chabrol.
Rapid developments in organic electronics promise low cost devices for applications such as OLED, organic transistors and organic photovoltaics on large-area glass or flexible substrates in the near future. The technology is very attractive as most device layers can be solution printed. But when directly patterned deposition is impossible, a post-patterning step is required and laser processing is gradually emerging as a key-enabling tool. DPSS lasers offer several advantages
including maskless, non-contact, dry patterning, but also scalable large area processing, well suited to roll-to-roll manufacturing at ?m resolutions. However, very few reports discuss in detail the merits of DPSS laser patterning technology, especially on flexible substrates. This paper describes the potential of ultrafast DPSS laser technology for
OLED fabrication on foil and, specifically, picosecond laser ablation of PEDOT:PSS on multilayered barrier/foil or metal grids aimed as a synthetic alternative to inorganic transparent conductive electrodes. Key requirements include:
(a) the complete removal of PEDOT layers without residue, (b) the complete absence of surface contamination from redeposited laser debris to avoid short circuiting and (c) no loss in performance of from laser exposure. We will demonstrate that with careful optimisation and appropriate choice of ultrafast laser, the above criteria can be fulfilled. A suitable process window exists resulting in clean laser structuring without damage to the underlying heat sensitive barrier layers whilst also containing laser debris. A low temperature ablation most likely proceeds via a stress-assisted (film fracture and ejection) process as opposed to vaporisation or other phase change commonly encountered with longer pulse lasers.
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