Recently, in works [1–2], the oligomeric composite films based on oligo-Nepoxypropylcarbazole
(PEPC) doped with the various concentration of anionic polymethine dye
(AD) were obtained and their spectral-luminescent and photoconductive properties were
investigated.

The kinetics found for the photoconductivity current (photocurrent) growth and relaxation in
these composite films with high anionic dye concentration (~ 5-10 wt.%) is anomalous for
photosemiconductor materials: the characteristic time of light-induced photocurrent growth is
much greater than the time for its dark relaxation after switching off excitation light. A prior
irradiation memory effect of these films was also discovered by authors of works [1–2].
However, the authors did not explain these unusual phenomena sufficiently.
In the present work, these non-trivial effects were interpreted in terms of a photoinduced
electron transfer from dye-anion to cation of dye molecule in the contact ion pairs, mediun
polarity, photogenerated long-lived uncharged intermediate states (neutral radical pairs), media
polarity-dependent mobility of the non-equilibrium charge carriers, and charge carriers mobilitydependent
rates of the mobile charge carriers photogeneration and transport processes. The
respective phenomenological model for internal photoeffect and photoconductivity in
investigated oligomeric film compositions was proposed by author. The corresponding
theoretical conclusions were qualitatively confirmed by data of additional experimental
investigations of the model photosensitive film polymeric composites obtained by author.
References:
1. N.A. Davidenko, I.I. Davidenko, A.A. Ishchenko, A.V. Kulinich, E.V. Mokrinskaya, S.L.
Studzinskii, and A.Yu. Shargaeva. Theoretical and Experimental Chemistry, 48, No. 1, 43-47
(2012).
2. N.A. Davidenko, A.A. Ishchenko, A.V. Kulinich, S.L. Studzinsky. Spectrochimica Acta A, 98,
271-274 (2012).