Photogeneration of electrons and holes in amorphous molecular semiconductors

Autor: A. J. Al-Kahdymi, N. G. Chuprin, Nadezhda A. Derevyanko, Alexander A. Ishchenko, N. G. Kuvshinskii, S. L. Studzinskii, N. A. Davidenko
Rok vydání: 2004
Předmět:
Zdroj: Physics of the Solid State. 46:1349-1356
ISSN: 1090-6460
1063-7834
DOI: 10.1134/1.1778463
Popis: This paper reports on the results of investigations into the photoconducting properties of amorphous molecular semiconductors based on films of two types: (i) poly(styrene) films doped with epoxypropylcarbazole (EPC) and a cationic polymethine dye (PD1) and (ii) poly(styrene) films doped with tetranitrofluorenone (TNF) and an anionic polymethine dye (PD2). Films of the first type possess p-type conductivity, whereas films of the second type exhibit n-type conductivity. It is found that, for films with n-type conductivity, unlike films with p-type conductivity, the activation energy of photogeneration of mobile charge carriers decreases with a decrease in the optical wavelength in the absorption range of the dyes. The possible mechanisms of the influence of the photoexcitation energy on the initial distance between charge carriers in electron-hole pairs are analyzed. The inference is made that, when the excess thermal energy of excited dye molecules dissipates at a low rate, the distance between the photogenerated electrons and photogeneration centers increases as compared to the distance between the photogenerated holes and photogeneration centers due to the electron-nucleus interaction.
Databáze: OpenAIRE
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