Jpn. J. Appl. Phys. 36 (1997) pp. 3522-3527  |Next Article|  |Table of Contents|
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Azo-compound-aggregate Induced Photocarrier Generation in Layered Organic Photoreceptors

Tatsuya Niimi and Minoru Umeda

(Received October 11, 1996; accepted for publication March 6, 1997)

The extrinsic photocarrier generation between an azo compound and a carrier transport molecule was investigated using aggregate and non-aggregate azo compounds in order to elucidate the high yield of photocarriers based on aggregation. The differences between the two systems were compared in terms of geminate-pair formation and dissociation efficiencies. The efficiencies of charge separation for generation of geminate pairs, which are independent of an electric field, do not vary significantly. Charge separation occurs via a fixed energy state which appears due to relaxation from a higher excited state of the photoexcited azo compound. This suggests that charge separation occurs between the two closest neighboring molecules. However, the efficiencies of geminate pair dissociation into free carriers are quite different; the electric field dependence of the photocarrier generation efficiency of the system containing a non-aggregated azo compound is much larger than that containing an aggregated one. According to the Onsager theory, the geminate hole-electron distance for dissociation is estimated to be 26 Å for the former system and 140 Å for the latter system. It is concluded that the primary geminate pair, the two closest neighboring molecules, relaxes to a looser condition in terms of distance based on the aggregation.

URL: http://jjap.jsap.jp/link?JJAP/36/3522/
DOI: 10.1143/JJAP.36.3522

References | Citing Articles (3)

1. P. M. Borsenberger and D. S. Weiss: Organic Photoreceptors for Imaging System (Marcel Dekker, New York, 1993) Chap. 11.
2. K. Arishima, H. Hiratsuka, A. Tate and T. Okada: Appl. Phys. Lett. 40 (1982) 279[AIP Scitation].
3. R. O. Loutfy, A. M. Hor, G. DiPaola-Baranyi and C. K. Hsiao: J. Imag. Sci. 29 (1985) 116.
4. P. M. Borsenberger, A. Chowdry, C. Hoestereey and W. Mey: J. Appl. Phys. 49 (1978) 5555[AIP Scitation].
5. J. Mizuguchi and A. C. Rochat: J. Imag. Sci. 32 (1988) 135.
6. J. Pacansky and R. J. Waltman: J. Am. Chem. Soc. 144 (1992) 5813.
7. M. Umeda: Denshi-Shashin Gakkaishi (Electrophotography) 27 (1988) 539 [in Japanese].
8. M. Umeda, T. Niimi and M. Hashimoto: Jpn. J. Appl. Phys. 29 (1988) 2746[JSAP].
9. M. Umeda and M. Hashimoto: J. Appl. Phys. 72 (1993) 117[AIP Scitation].
10. T. Niimi and M. Umeda: J. Appl. Phys. 74 (1993) 465[AIP Scitation].
11. M. Umeda, T. Shimada, T. Aruga, T. Niimi and M. Sasaki: J. Phys. Chem. 97 (1993) 8531[CrossRef].
12. P. M. Borsenberger and D. S. Weiss: Organic Photoreceptors for Imaging System (Marcel Dekker, New York, 1993) Chap. 6.
13. M. Umeda and M. Yokoyama: Jpn. J. Appl. Phys. 34 (1995) L44[JSAP].
14. M. Umeda and T. Niimi: J. Imag. Sci. Technol. 38 (1994) 281.
15. T. Niimi and M. Umeda: J. Appl. Phys. 76 (1994) 1269[AIP Scitation].
16. M. Umeda and T. Niimi: Jpn. J. Appl. Phys. 33 (1994) L1789[JSAP].
17. T. Niimi and M. Umeda: Adv. Mater. 7 (1995) 481.
18. M. Hashimoto: Denshi-Shashin Gakkaishi (Electrophotography) 25 (1986) 230 [in Japanese].
19. T. Aruga, M. Sasaki, T. Shimada and H. Adachi: Proc. 7th IS&T NIP Congr., ed. K. Pietrowski (Society for Imaging Science and Technology, Portland, 1991) Vol. 1, p. 310.
20. A. Burawoy and A. R. Thompson: J. Chem. Soc. (1953) 1443.
21. R. L. Reeves and R. S. Kaiser: J. Org. Chem. 35 (1970) 3670.
22. K.-Y. Law, S. Kaplan, R. Crandall and I. W. Tarnawskyj: Chem. Mater. 5 (1993) 557.
23. M. Ohta: Ricoh Tech. Rep. 8 (1982) 14 [in Japanese].
24. M. Sasaki: Nippon Kagaku Kaishi 1986 (1986) 397 [in Japanese].
25. L. Onsager: J. Chem. Phys. 2 (1934) 599[AIP Scitation].
26. L. Onsager: Phys. Rev. 54 (1938) 554[APS].