Photoelectric and electrical properties of soluble polyphenylquinolines containing an oxygen or phenylamine bridge group
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PHOUS, VITREOUS, POROUS, ORGANIC, AND MICROCRYSTALLINE SEMICONDUCTORS; SEMICONDUCTOR COMPOSITES
Photoelectric and Electrical Properties of Soluble Polyphenylquinolines Containing an Oxygen or Phenylamine Bridge Group between Quinoline Moieties E. L. Aleksandrovab, V. M. Svetlychnyia^, L. A. Miagkovaa, T. N. Nekrasovaa, A. R. Tameevc, A. V. Vannikovc, and V. V. Kudryavtseva aInstitute
of Macromolecular Compounds, Russian Academy of Sciences, St. Petersburg, 199004 Russia ^e-mail: [email protected] bIoffe Physicotechnical Institute, Russian Academy of Sciences, St. Petersburg, 194021 Russia cFrumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, 119991 Russia Submitted May 27, 2008; accepted for publication June 10, 2008
Abstract—Photoelectric and electrical properties of polyphenylquinolines differing in the structure of donor bridge groups between quinoline moieties have been studied. It is demonstrated that films of the polymers synthesized exhibit a photosensitivity at the level of 105 cm2 J–1 (integrated sensitivity 5 × 10–4 lx–1 · s–1), with a quantum yield of carrier photogeneration of 0.07 and a carrier drift mobility on the order of 10–6 cm2 V–1 s–1. The fact that the electron and hole drift mobilities in polyphenylquinoline with a phenylamine bridge group are balanced makes the polymer promising for development of film-type devices based on the bipolar conductivity of a material (e.g., single-layer light-emitting diode). PACS numbers: 72.40.+w, 73.61.Ph, 78.55.Qr, 78.66.Qn, 78.40.Me DOI: 10.1134/S106378260903018X
1. INTRODUCTION A first priority in the development of new polymers for organic light-emitting diodes (LEDs) is a search for polymers that exhibit high-efficiency electroluminescence (EL) and have properties stable against external disturbances. Of interest in this regard are aromatic nitrogen-containing representatives of the class of polyphenylquinolines:
X N
N
Ar
n
where R = C6H13–. It was noted that this polymer shows luminescence in the spectral range 570–580 nm (with a quantum efficiency as high as 0.035%) and can be used as an electron-transport layer in a double-layer LED [2]. If aliphatic substituents are introduced into the structure of the quinoline moieties instead of phenyl substituents and derivatives containing para-phenylene, 4,4'-(biphenylene), stilbene, 5,5'-(bithienylene), bis(thienyl)vinylene, and 3,7'-phenothiazinylene groups are used in the Ar moiety, the polymers become soluble in organic solvents. The synthesis and structure of polyquinolines of this kind were described in [3]:
.
C8H17
Kim et al. [1, 2] have synthesized 2,6-polyphenylquinoline containing an oxygen bridge group between quinoline moieties and 9,9-di-n-hexylfluorene in the Ar-moiety:
* N
N Ar * C8H17 n
R
O N
R
,
N
Ar =
n
359
;
;
360
ALEKSANDROVA et al.
It was shown that these polymers have a bipolar conductivity and the peak of the luminescence band of the carbazolyl-containing polymer is shifted to longer wavelengths as compared with that
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