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Home  >  Journal list  >  Polymer Journal  >  Vol.17  No.4 (1985)  >  pp.557-565

Polymer Journal
<<Previous article Vol.17  No.4 (1985)   pp.557 - 565 Next article>>

Hole Transport in Amorphous Films of Poly(N-vinylcarbazole), Copolymers of N-Vinylcarbazole with Styrene, Polystyrene Molecularly-Doped with N-Isopropylcarbazole, and 1,3-Di(N-carbazolyl)propane

Akira Itaya1), Ken-ichi Okamoto1) and Shigekazu Kusabayashi2)
1) Department of Chemical Engineering, Faculty of Engineering, Yamaguchi University
2) Department of Applied Chemistry, Faculty of Engineering, Osaka University


ABSTRACT:  The hole drift mobility in amorphous films of poly(N-vinylcarbazole) prepared by the radical and cationic polymerizations (abbreviated as PVCz(r) and PVCz(c), respectively), copolymers of N-vinylcarbazole with styrene (VCz-St), polystyrene molecularly-doped with N-isopropylcarbazole (IPCz-PSt), and 1,3-di(N-carbazolyl)propane (DCzP(a)) was investigated by the time-of-flight method. The electric field and temperature dependence of the mobility of all the materials fitted the Gill’s empirical equation. The mobility of PVCz(r) was larger than that of PVCz(c) by a factor of ca. 5—6. By heat-treatment at a temperature above the glass transition temperature, PVCz(r) film was crystallized and its mobility increased by a factor of ca. 5. The thermal-crystallization of PVCz(c) film was much more difficult than that of PVCz(r) film and the mobility of PVCz(c) film hardly changed with heat-treatment. These significant differences between PVCz(r) and PVCz(c) seem to be attributable to the difference in their tacticity. The mobility of PVCz(r) increased about twice as much with an increase in the sequence length of VCz chain from 20 to 200, while the mobility of PVCz(c) was independent of it. This may be qualitatively explained by the existence of the chain-end vinyl group in PVCz(r). Under usual conditions (T=296 K, E=1.6×105 V cm−1), the mobility of low molecular-weight compounds (DCzP(a) and IPCz-PSt) was larger than that of polymeric compounds (PVCz and VCz-St). Using the results of a comparison of the values of parameters in the Gill’s equation for these films, this was explained by a negative polymer effect due to the higher value of T0.


Keyword:
Drift Mobility/ Transient Photocurrent/ Photoconduction/ Carrier Transport/ Poly(N-vinylcarbazole)/ N-Vinylcarbazole Copolymer/ 1,3-Di(N-carbazolyl)propane/ N-Isopropylcarbazole

Published online: March 03, 2006
© Copyright, 2006 by The Society of Polymer Science, Japan

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