Chemistry Reference
In-Depth Information
Table 3.1.
Typical experimental conditions for the growth of mm or larger single
crystals of organic semiconductors
T
source
T
dep
gas
Material
Arrangement
(K)
(K)
(ml/min)
α
-6T LT
V
553-573
40 (Ar,He,N
2
+H
2
)
α
-6T HT
V
593
563
150 (Ar)
α
-6T LT
V
593
523
150 (Ar)
α
-6T HT
H
593
563
40 (Ar,He,N
2
+H
2
)
α
-4T LT
V
413
40 (Ar)
α
-4T HT
V
453
40 (Ar)
α
-4T HT
H
458
413
60 (N
2
+H
2
)
anthracene
H
433
423
50 (He)
pentacene
H
558
493
...
558
30 (N
2
+H
2
)
CuPc
V
743
723
75 (He)
Note:
This table is adapted from Table 1 of Laudise
et al.
, 1998. H and V represent hori-
zontal and vertical.
T
source
and
T
dep
stand for source and deposition temperatures and
gas
corresponds to the gas flow rate.
et al.
, 2001). The source material was sublimed at 550 K and crystallized at the other
end of the tube at approximately 490 K. The growth was performed under a stream
of N
2
(99.999% purity) and H
2
gases (99.995% purity), with a volume percentage
of 5.1% H
2
. This yielded almost cm-sized violet crystals in the form of platelets
and needles. Also, at a different part of the tube, a small amount of hydrogenated
pentacene crystals (red needles) was found. Lowering the flow rate yielded a larger
fraction of hydrogenated pentacene. At lower hydrogen content or if no ultrapure
inert transport gas is used, the pentacene oxidizes, forming pentacenequinone, and
small brown needles crystallize (see Section 2.1 for the synthesis of pentacene from
pentacenequinone). Thin pentacene crystals in the form of lamellae up to 10 mm
long and 1-3 mm wide have been obtained working in similar conditions (Siegrist
et al.
, 2001).
Crystallization of self-confined solutions
Exploring the surface morphology at the nanometre scale of MOMs leads to sur-
prises as shown before with the formation of nanovolcanoes. Freshly prepared
single crystals of EDT-TTF-(CONHMe)
2
exhibit the morphology depicted in
Fig. 3.7. Dark needle-shaped single crystals are synthesized by reacting a CH
3
CN
solution of EDT-TTF-(CO
2
Me)
2
with an excess of CH
3
NH
2
. After stirring at RT for
24 hours, the resulting precipitate is filtered, recrystallized twice from CH
3
CN and
dried in air. The tapping mode AFM (TMAFM) images shown here were taken at
