Chemistry Reference
In-Depth Information
TABLE 10.2 10% weight decreasing (T
d10%
) and glass transition temperatures (T
g
)of
phenylazomethine dendrimers
T
d10%
(
C)
T
g
(
C)
Dendrimer
PPh-DPA G1
400
50
PPh-DPA G2
514
148
PPh-DPA G3
511
174
PPh-DPA G4
521
188
a
Por-DPA G1
531
a
Por-DPA G2
528
Por-DPA G3
523
195
Por-DPA G4
531
201
a
No clear phase transition was observed.
of electron transfer between the core and an electrode surface [53,54,74]. In the cyclic
voltammograms, the oxidation and reduction peak separation became greater with the
increasing generation number, suggesting a slower electron transfer rate constant (k
0
).
The UV-vis absorption measurements and spin-lattice relaxation times (T
1
) from the
NMRmeasurements revealed that the solvent molecules are gradually excluded from
the interior of these larger DPAs [54].
The physical properties noted above significantly contribute to the formation of
a homogeneous film and further processing. Indeed, a spin-cast film on a flat substrate
has a very low roughness, and the dendrimer molecules were assembled in a nearly
hexagonal closest packed structure (Figure 10.16). In the next section, examples of the
application in an OLED device will be introduced.
FIGURE 10.16
An atomic force microscope (AFM) image of the spin-cast film of the
phenylazomethine dendrimer on a mica surface. The bottom part on the right-hand side shows a
cross-sectional AFM image corresponding to the dashed line in the top view (upper part).
