ELECTROCHEMICAL NANOFABRICATIONS: A GENERAL REVIEW - Electrochemical Nanofabrication: Principles and Applications - page 31

out the space between the ZnO nanowires and produce only a very
thin coverage of the nanowire tips. The polystyrene layer thickness
at the tips can be further reduced by the plasma etching treatment
to make the n-type ZnO tip junctions outside. A top contact
consisting of a thin p-type poly(3,4-ethylene dioxythiophene):
poly(styrenesulfonate) (PEDOT:PSS) layer and an evaporated Au
film are provided to serve as the hole injection anode in the LED.
A flexible LED can be realized when electrochemical depositing
the ZnO nanowire on flexible transparent polymer substrates (e.g.
polyethylene terephthalate, PET) coated with indium-tin oxide
(ITO) [140]. The infrastructure of such flexible LED is illustrated in
Fig. 1. 14 . This device exhibits electroluminescence over most of the
visible spectrum at moderate forward bias.

Design scheme for a flexible LED structure consisting of
vertically oriented single crystalline nanowires grown electrochemically
on a polymeric ITO-coated substrate. The top contact consists of p-type
polymer (PEDOT:PSS) and an evaporated Au layer. Light is emitted
through the transparent polymer [140]. Reproduced by kind permission
from the publisher.

Figure 1.14