Saturday, October 19, 2013

Ambiplar vs bipolar charge transport - whats the difference?

I am writing this open letter to raise the awareness of all scientists who do not differentiate between ambipolar and bipolar charge transport. My deepest respect to James G. Champlain who understands that well and explained it in his publication, but here is my triple C explanation.

Please, do not use terminology "ambipolar charge transport", "ambipolar mobility" in disordered systems, such as organic semiconductors. In general, these Langevin-type materials typically are undoped, there are no minority carriers nor their transport in these films, therefore "ambipolar transport" terminology does not apply here. You can call charge transport as bipolar, or name charge carrier mobility as bipolar, and use definitions of bipolar electron and hole movement.
Be careful, because this goes as far as if you state (god forbid in the title of your paper) "ambipolar charge transport" in organic field effect transistors, you show that there is some space left for you to learn the majority/minority carrier concepts in solid state and semiconductor device physics.

Hehe, now when I scared you enough, the fact is that it is still safe to call organic Field Effect Transistor (FET) as "ambipolar FET". When talking about Langevin-type organic systems, "ambipolar FET" is ok, but "ambipolar charge transport" is NOT ok. Charge transport and FET are two different things.

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