Tuesday, July 10, 2007

Organic Microelectronics workshop

I just spent two days at the 3rd Annual Organic Microelectronics Workshop, meeting this year in Seattle. The workshop, sponsored jointly by the ACS, MRS, IEEE, and APS, was really very good - about 90 participants, and most of the big movers in the field. The talks were a great mix from the very applied (e.g. trying to optimize solvent conditions to avoid the coffee ring problem when inkjet or gravure printing solution-processable organic semiconductors) to the basic physics and chemistry of these materials. Among the things that I learned:
  • Among the single-crystal organic semiconductors, rubrene is truly special in a number of ways. The most important point from the perspective of understanding electronic transport is that it can be made particularly pure, and oxidation in this material is reversible, unlike, e.g., pentacene.
  • With polymer electrolytes, it is possible to make field-effect devices with gated surface charge densities exceeding 10^14 carriers/cm^2. I'd seen a couple of papers on this, and it's looking very impressive as a technique.
  • Clever phase separation tricks can produce self-assembling organic devices that encapsulate themselves within a protective coating.
  • RFID tags from Si are very very cheap.
  • When developing a manufacturing process, "'Good enough' is good enough, and 'better' is not necessarily better."


Anonymous said...

On that last comment, is there an example from the conference you can share?

Doug Natelson said...

Sure - the speaker was James Im, and he has been a major player over the last 15 years in laser recrystallization of Si. Basically the idea is to deposit amorphous Si onto some substrate (glass or even plastic), and then used pulsed laser heating to recrystallize it, since (poly)crystalline Si has better device performance for many applications. They have three different versions of the process that he discussed - a quick-and-dirty method, a more refined approach with more steps, and an even further tweaked approach that can grow decently large single crystal Si at the end. His point was that the quick-and-dirty method produced devices of high enough quality to be industrially viable, while the more sophisticated processes (that make better material in the end) were not economically sensible for mass manufacturing right now.