A number of novel vinyl monomers containing either a fluorescent or a phosphorescent moiety were synthesized. The vinyl
monomers have either hole or electron transporting properties and luminescence in near-UV, blue, green, to red. The overall
charge transport properties and emission hue can be tuned by applying and the various monomers at different mix ratios.
The vinyl monomers were copolymerized into high molecular weight yet soluble conductive copolymers using traditional
solution free radical polymerization method. The vinyl monomers prepared including electron transporting
11-vinyl-phenanthro[9.10-b]quinoxaline (QP) and 1-vinyl pyrene (PY), hole transporting
9-(4-methoxyphenyl)-3-vinyl-9H-carbazole (KPA) and N-phenyl-N-(4-vinylphenyl) naphthalene -1-amine (NPA), and a
red-emitting phosphorescent monomer based on the Europiujm complex [Eu(DBM)<sub>3</sub>H-EtPIP]. The optical, thermal and
electrical properties of the copolymers were characterized. Homojunction OLED based on the copolymers were prepared
by spin-coating. The EL spectra and I-V-L characteristics were obtained and will be reported.
<sup></sup>A fluorescent star-shaped oligomer with a nitrogen atom as a core and
both a hole transporting arylamine and an electron transporting
1,3,4-oxadiazole moiety, tri(4-(5-phenyl-1, 3, 4-oxadiazol-2-yl)phenyl)amine
(TPOPA), has been designed and synthesized using a 5-step reaction procedure. The
synthesized compound was characterized by elemental analysis, <sup>1</sup>H-NMR and mass
spectroscopy. Thermogravimetric (TG) and differential scanning calorimetry (DSC)
analysis show that TPOPA exhibits high thermal stability (T<sub>d</sub>, 373°C) and high
glass-transition temperature (T<sub>g</sub>, 116 °C). Photoluminescence measurements indicate
that the star-shaped oligomer shows intense blue emission peaked at 445 nm with a
high quantum yield of 0.68 under near UV light excitation. The HOMO value of
TPOPA is -5.64 eV and the LUMO is -2.58 eV based on the electro-chemical
determinations. Reversible anodic oxidation results suggest that the hole-transporting
is predominant for TPOPA. Two single layered devices were fabricated by vacuum
evaporation with configurations of ITO / CuPC (15 nm) / TPOPA (95 nm) / Ca(30 nm)
/ Al(100 nm) (device 1) and ITO / CuPC(15 nm) / TPOPA (175 nm) / Ca(30 nm) /
Al(100 nm) (device 2), where TPOPA was used both as emitter and carrier -
transporting material, CuPC as a hole-injection and electron block material. The
devices show blue wide-band emission peaked at 438 nm with a maximum luminance
of 650 cd/m<sup>2</sup> and 512 cd/m<sup>2</sup> under an operating voltage of 12 V, respectively.
Electroluminescent bipolar small molecules have been attracted with great interests recently. They are found to exhibit many interesting features such as (i) reducing the structural complexity of organic light emitting diodes (OLEDs) from multilayer heterojunction to monolayer homojunction devices; (ii) offering molecular p/n junction, and (iii) minimizing the formation of exciplexes. In this paper, the optical and electrical properties of novel oxadiazole-triphenylamine derivatives will be investigated. The derivatives are N-phenyl-N-(4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl)phenylamine (POT) and N-phenyl-N-(4-(5-p-tolyl-1,3,4-oxadiazol-2-yl)phenyl)phenylamine (m-POT). The absolute absorption coefficient and refractive index have been investigated by ellipsometry and modeling. The electron mobility of POT at room temperature has been studied. The results show that the derivatives have bipolar characteristics. The electron-transporting properties of POT is better than that of m-POT. The EL emission peaks of POT and m-POT are the same at 435nm which match with their photoluminescent (PL) peaks.