<s>
Molecular	B-Algorithm
electronics	I-Algorithm
is	O
the	O
study	O
and	O
application	O
of	O
molecular	O
building	O
blocks	O
for	O
the	O
fabrication	O
of	O
electronic	O
components	O
.	O
</s>
<s>
Due	O
to	O
the	O
prospect	O
of	O
size	O
reduction	O
in	O
electronics	O
offered	O
by	O
molecular-level	O
control	O
of	O
properties	O
,	O
molecular	B-Algorithm
electronics	I-Algorithm
has	O
generated	O
much	O
excitement	O
.	O
</s>
<s>
Molecular	B-Algorithm
scale	I-Algorithm
electronics	I-Algorithm
,	O
also	O
called	O
single-molecule	B-Algorithm
electronics	I-Algorithm
,	O
is	O
a	O
branch	O
of	O
nanotechnology	O
that	O
uses	O
single	O
molecules	O
,	O
or	O
nanoscale	O
collections	O
of	O
single	O
molecules	O
,	O
as	O
electronic	O
components	O
.	O
</s>
<s>
In	O
single-molecule	B-Algorithm
electronics	I-Algorithm
,	O
the	O
bulk	O
material	O
is	O
replaced	O
by	O
single	O
molecules	O
.	O
</s>
<s>
The	O
molecules	O
used	O
have	O
properties	O
that	O
resemble	O
traditional	O
electronic	O
components	O
such	O
as	O
a	O
wire	O
,	O
transistor	B-Application
,	O
or	O
rectifier	B-Algorithm
.	O
</s>
<s>
This	O
concept	O
of	O
using	O
a	O
molecule	O
as	O
a	O
traditional	O
electronic	O
component	O
was	O
first	O
presented	O
by	O
Aviram	O
and	O
Ratner	O
in	O
1974	O
,	O
when	O
they	O
proposed	O
a	O
theoretical	O
molecular	O
rectifier	B-Algorithm
composed	O
of	O
donor	O
and	O
acceptor	O
sites	O
which	O
are	O
insulated	O
from	O
one	O
another	O
.	O
</s>
<s>
Single-molecule	B-Algorithm
electronics	I-Algorithm
is	O
an	O
emerging	O
field	O
,	O
and	O
entire	O
electronic	O
circuits	O
consisting	O
exclusively	O
of	O
molecular	O
sized	O
compounds	O
are	O
still	O
very	O
far	O
from	O
being	O
realized	O
.	O
</s>
<s>
Molecular	B-Algorithm
electronics	I-Algorithm
operates	O
in	O
the	O
quantum	O
realm	O
of	O
distances	O
less	O
than	O
100	O
nanometers	O
.	O
</s>
<s>
Because	O
the	O
current	O
photolithographic	B-Algorithm
technology	O
is	O
unable	O
to	O
produce	O
electrode	O
gaps	O
small	O
enough	O
to	O
contact	O
both	O
ends	O
of	O
the	O
molecules	O
tested	O
(	O
in	O
the	O
order	O
of	O
nanometers	O
)	O
alternative	O
strategies	O
are	O
put	O
into	O
use	O
.	O
</s>
<s>
There	O
are	O
some	O
concepts	O
for	O
contacting	O
organic	O
molecules	O
using	O
semiconductor-only	O
electrodes	O
,	O
for	O
example	O
by	O
using	O
indium	O
arsenide	O
nanowires	B-Architecture
with	O
an	O
embedded	O
segment	O
of	O
the	O
wider	O
bandgap	O
material	O
indium	O
phosphide	O
used	O
as	O
an	O
electronic	O
barrier	O
to	O
be	O
bridged	O
by	O
molecules	O
.	O
</s>
<s>
One	O
of	O
the	O
biggest	O
hindrances	O
for	O
single-molecule	B-Algorithm
electronics	I-Algorithm
to	O
be	O
commercially	O
exploited	O
is	O
the	O
lack	O
of	O
means	O
to	O
connect	O
a	O
molecular	O
sized	O
circuit	O
to	O
bulk	O
electrodes	O
in	O
a	O
way	O
that	O
gives	O
reproducible	O
results	O
.	O
</s>
<s>
The	O
first	O
time	O
in	O
history	O
molecular	B-Algorithm
electronics	I-Algorithm
are	O
mentioned	O
was	O
in	O
1956	O
by	O
the	O
German	O
physicist	O
Arthur	O
Von	O
Hippel	O
,	O
who	O
suggested	O
a	O
bottom-up	O
procedure	O
of	O
developing	O
electronics	O
from	O
atoms	O
and	O
molecules	O
rather	O
than	O
using	O
prefabricated	O
materials	O
,	O
an	O
idea	O
he	O
named	O
molecular	O
engineering	O
.	O
</s>
<s>
In	O
this	O
article	O
named	O
Molecular	O
Rectifiers	B-Algorithm
,	O
they	O
presented	O
a	O
theoretical	O
calculation	O
of	O
transport	O
through	O
a	O
modified	O
charge-transfer	O
molecule	O
with	O
donor	O
acceptor	O
groups	O
that	O
would	O
allow	O
transport	O
only	O
in	O
one	O
direction	O
,	O
essentially	O
like	O
a	O
semiconductor	O
diode	O
.	O
</s>
<s>
This	O
was	O
a	O
breakthrough	O
that	O
inspired	O
many	O
years	O
of	O
research	O
in	O
the	O
field	O
of	O
molecular	B-Algorithm
electronics	I-Algorithm
.	O
</s>
<s>
The	O
linear-backbone	O
polymers	O
such	O
as	O
polyacetylene	B-Language
,	O
polypyrrole	B-Algorithm
,	O
and	O
polyaniline	B-Algorithm
are	O
the	O
main	O
classes	O
of	O
conductive	O
polymers	O
.	O
</s>
<s>
Poly(3-alkylthiophenes )	O
are	O
the	O
archetypical	O
materials	O
for	O
solar	O
cells	O
and	O
transistors	B-Application
.	O
</s>
<s>
With	O
the	O
availability	O
of	O
stable	O
and	O
reproducible	O
dispersions	O
,	O
poly(3,4-ethylenedioxythiophene )	O
(	O
PEDOT	B-Algorithm
)	O
and	O
polyaniline	B-Algorithm
have	O
gained	O
some	O
large-scale	O
applications	O
.	O
</s>
<s>
While	O
PEDOT	B-Algorithm
is	O
mainly	O
used	O
in	O
antistatic	O
applications	O
and	O
as	O
a	O
transparent	O
conductive	O
layer	O
in	O
the	O
form	O
of	O
PEDOT	B-Algorithm
and	O
polystyrene	O
sulfonic	O
acid	O
(	O
PSS	O
,	O
mixed	O
form	O
:	O
PEDOT:PSS	O
)	O
dispersions	O
,	O
polyaniline	B-Algorithm
is	O
widely	O
used	O
to	O
make	O
printed	O
circuit	O
boards	O
,	O
in	O
the	O
final	O
finish	O
,	O
to	O
protect	O
copper	O
from	O
corrosion	O
and	O
preventing	O
its	O
solderability	O
.	O
</s>
<s>
Recently	O
supramolecular	O
chemistry	O
has	O
been	O
introduced	O
to	O
the	O
field	O
,	O
which	O
provide	O
new	O
opportunity	O
for	O
developing	O
next	O
generation	O
of	O
molecular	B-Algorithm
electronics	I-Algorithm
.	O
</s>
