posted on 2015-07-08, 00:00authored byJiye Kim, So Hee Lee, Haekyoung Kim, Se Hyun Kim, Chan Eon Park
We
successfully fabricated high performance bottom-contact organic
field-effect transistors (OFETs) using silver nanowire (AgNW) network
electrodes by spray deposition. The synthesized AgNWs have the dimensions
of 40–80 nm in diameter and 30–80 μm in length
and are randomly distributed and interconnected to form a 3D hollow
framework. The AgNWs networks, deposited by spray coating, yield an
average optical transmittance of up to 88% and a sheet resistance
as low as 10 ohm/sq. For using AgNWs as source/drain electrodes of
OFETs with a bottom-contact configuration, the large contact resistance
at the AgNWs/organic channel remains a critical issue for charge injection.
To enhance charge injection, we fabricate semiconductor crystals on
the AgNW using an adsorbed residual poly(N-vinylpyrrolidone)
layer. The resulting bottom-contact OFETs exhibit high mobility up
to 1.02 cm2/(V s) and are similar to that of the top-contact
Au electrodes OFETs with low contact resistance. A morphological study
shows that the pentacene crystals coalesced to form continuous morphology
on the nanowires and are highly interconnected with those on the channel.
These features contribute to efficient charge injection and encourage
the improvement of the bottom-contact device performance. Furthermore,
the large contact area of individual AgNWs spreading out to the channel
at the edge of the electrode also improves device performance.