Growth of concentration of the anion polymethine dye in the films of poly-N-epoxypropylcarbazole involves
increase of quenching of photoluminescence in external electric field as well as appearance of longwave
band of the photoluminescence and photoconductivity within visible spectral range. It was ascertained
that associates of ionic pairs of the dye arise when the concentration increases. Anomalous for semiconductor
materials kinetics of the photocurrent growth and relaxation was observed in the films of these
composites: time of the photocurrent growth is much less than the time of its relaxation after the light is
switched off. Effect of memory of preliminary illumination with light was observed in the films.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3527

Davidenko, I.I.

Davidenko, N.A.

Grabchuk, G.P.

Ishchenko, A.A.

Mokrinskaya, E.V.

Studzinsky, S.L.

Tonkopieva, L.S.

SocioEconomic Challenges Journal (Sumy State University)

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE NANOMATERIALS: APPLICATIONS AND PROPERTIES 
Vol. 1 No 4, 04NEA06(4pp) (2012) 
 
 
2304-1862/2012/1(4)04NEA06(6) 04NEA06-1  2012 Sumy State University 
Internal Photoeffect in Films of Poly-N-Epoxypropylcarbazole with High Concentration of 
Anion Polymethine Dye 
 
E.V. Mokrinskaya1,* , S.L. Studzinsky1,†, N.A. Davidenko1,‡, I.I. Davidenko1, A.A. Ishchenko2, 
G.P. Grabchuk2, L.S. Tonkopieva1 
 
1 Kiev Taras Shevchenko National University, Volodymyrs’ka Str., 64, 01601 Kyiv. Ukraine 
2 Institute of Organic Chemistry NAS of Ukraine, Murmans’ka Str., 5, 02094 Kyiv, Ukraine 
 
(Received 12 June 2012; revised manuscript received 05 July 2012; published online 22 August 2012) 
 
Growth of concentration of the anion polymethine dye in the films of poly-N-epoxypropylcarbazole in-
volves increase of quenching of photoluminescence in external electric field as well as appearance of long-
wave band of the photoluminescence and photoconductivity within visible spectral range. It was ascer-
tained that associates of ionic pairs of the dye arise when the concentration increases. Anomalous for semi-
conductor materials kinetics of the photocurrent growth and relaxation was observed in the films of these 
composites: time of the photocurrent growth is much less than the time of its relaxation after the light is 
switched off. Effect of memory of preliminary illumination with light was observed in the films. 
 
Keywords: Photoconducting Polymers, Dyes, Spectra of Adsorption and Fluorescence, Associates, Kinetics 
of Photoconductivity, Recombination Centers. 
 
 PACS numbers: 73.50.Pz, 73.50.Gr, 78.55.Qr, 78.66.Sq 
 
 
                                                          
* mokrinskaya@ukr.net 
† studzs@mail.ru 
‡ ndav@univ.kiev.ua 
1. INTRODUCTION 
 
The films of polymeric composites (FPC) doped with 
organic dyes are commonly used in informatic record-
ing and electroluminescent media as well as in photoe-
lectric converters of solar energy [1 – 5]. In FPC mono-
meric dye molecules play role of centers of light absorp-
tion and photogeneration of non-equilibrium charge 
carriers. Considerable progress is reached in control of 
photophysical and electrophysical properties of FPC by 
adjustment of chemical structure of the dye and poly-
mer. But these properties also depend on geometric size 
of FPC components [6-10]. Such dependency is caused 
by transformation of energetic structure of dopants 
which are in polymeric matrix. Thus, there is scientific 
and practical interest on development of new photoac-
tive media based on FPC where inner photoeffect is 
realized due to size effects in dopants. The polymethine 
dyes [11] are the most interesting amongst organic dyes 
for application for light energy conversion. The work is 
aimed in investigation of photoelectric and spectral-
luminescent properties of the films of polymeric compo-
sites with high concentration of organic dye. 
 
2. THE SAMPLES AND  EXPERIMENTAL 
TECHNIQUE 
 
Poly-N-epoxypropylcarbazole (PEPC) and anionic 
dye An5 were used as FPC components. For compari-
son the same dye was used in FPC based on non-
photoconducting polyvinylbutyrale (PVB). 
The samples were prepared as the structures with 
free surface [glass substrate – electroconducting layer 
SnO2 : In2O3 – FPC] and sandwich-structures [glass 
substrate – electroconducting layer SnO2: In2O3 – FPC 
– Ag]. Concentration (N) of An5 was 0.5 – 10 mas. , 
FPC thickness was 1 – 1.5 m.  
 
 
The technique of measurement of optical density 
(D), photoluminescence intensity (IL) within the range 
  400 – 900 nm, density (jPH) of photocurrent is de-
scribed in [2, 12]. Green laser with maximum of irradi-
ation at 1  532 nm and He-Ne laser with 2  633 nm 
were used for excitation of photoluminescence and for 
investigation of photoconducting properties of FPC. The 
values D and IL were measured before and after appli-
cation of external electric field with strength 
Е  108 V/m. Parameters δDE  (DE – D0)/D0 and 
δILE   (ILE – IL0)/IL0, where D0 and IL0 are the values D 
and IL before application of the field (E), DE and ILE are 
the values D and IL after application of the field, were 
calculated using experimental results. Light intensity 
(I) at 1 and 2 was changed by neutral light filters 
within the range 1 – 50 W/m2. The value of electric 
voltage (U) which was applied to electric contacts in the 
samples of sandwich-structure was changed within the 
range 1 – 200 V. For measurements of fluorescence 
spectra and for excitation of fluorescence in FPC spec-
tral fluorometer Solar CM2203 was used. All meas-
urements were done at room temperature which corre-
sponds to conditions of FPC practical applications. 
 E.V. MOKRINSKAYA, S.L. STUDZINSKY, N.A. Davidenko, ET AL. PROC. NAP 1, 04NEA06 (2012) 
 
 
04NEA06-2 
Quantum-chemical calculations of molecules N-
methylcarbazole (as a model monomer of PEPC) and 
anion An5 were done by non-empirical method 
DFT/B3LYP in 6-31G(d,p) basis using program package 
PC Gamess/Firefly [13]. 
 
3. EXPERIMENTAL RESULTS AND DISCUS-
SION 
 
In the samples of sandwich-structure based on 
PEPC with N < 5 mas. % An5 photocurrent was not 
observed. In the samples with N > 5 mas. % An5 photo-
current was observed both for  λ1 and for λ2. In the 
samples with N = 10 mas. % An5 for U = 100 V, I = 50 
W/m2 the value jPH is 10-3 А/m2 under illumination with 
light with λ1 and 2·10-4 А/m2 under illumination with 
light with λ2. In the similar structures with PVB photo-
current was not observed. Dependencies jPH on U can 
be described by analytical function jPH  UmPH, which is 
usually used for analysis of currents in semiconductor 
materials. Power exponent mPH  2.1 for 1 and 1.4 for 
2. The value jPH does not depend on polarity U. The 
dependencies of jPH on I with λ1 and λ2 are close to line-
ar. The last fact means that effect of photoconductivity 
which is not caused by two-quantum processes was 
discovered.  
 Discovered in the work photoeffect is unusual. It can 
not be explained by formation of electron-hole pairs 
(EHP) caused by electron transfer from carbazole frag-
ment PEPC to excited molecule An5 due to difference 
HOMO energy (HOMO energy of the polymer which was 
calculated for N-methylcarbazole is –5.3280 еV and it is 
–2.2205 eV for An5 anion).  
Additional investigations were carried out for deter-
mination of reasons of appearance of inner photoeffect 
upon growth of An5 concentration. Influence of external 
electric field on spectra of absorption and photolumines-
cence was observed in all investigated samples based on 
PEPC (Fig. 1).  
When electric field is switched on the values D0 and 
IL0 reach the values DE and ILE during time interval  1 
s, which is close to time of electric charge of geometric 
capacity of the sample. After electric field switching off 
all changes of spectra stop. Peculiarities of spectra 
changes depend on dye concentration. In FPC with 
N  5 mas.  when electric field is switched off within 
short wavelength range absorption intensity increases 
(δDE  0), intensity of photoluminescence decreases 
(δILE  0). Within the long wavelength range the effects 
are opposite (δDE  0, δILE  0) (Fig. 1, c). Earlier [2, 14] 
the similar changes were observed in photoconducting 
and non-photoconducting FPC with low concentration 
of symmetric polymethine dyes. These changes were 
explained by intramolecular redistribution of electronic 
density under influence of external electric field. But 
we have ascertained that upon N growth the dependen-
cy δDE ( ) does not change whereas the dependency 
δILE( ) essentially transforms. The last fact reveals 
itself in quenching of luminescence upon application of 
electric field (δILE  0) in FPC with N  5 mas. . This 
quenching increases upon N growth (Fig. 1, d). That 
corresponds to the model considerations described in 
[1, 2]. Luminescence quenching of organic dyes in pho-
toconducting FPC under electric field influence is ex-
plained by formation and dissociation of EHP, namely 
by decrease of probability of radiative recombination of 
EHP. 
One can suppose, that increase of An5 concentration 
in PEPC involves appearance of aggregates of dye mol-
ecules. But attributes of aggregation of An5 anion in 
FPC absorption spectra are absent. N growth involves 
appearance of new bands in absorption spectrum but 
shape of the curve changes weakly. Universal for or-
ganic dye outline of long wavelength absorption band 
preserves its original appearance [11]. Characteristic 
attributes of association are absent in photolumines-
cence spectrum for N  0.5 mas.  as well. Photolumi-
nescence band does not depend on light wavelength of 
excitation and it is inversely similar to absorption band 
(Fig. 1, a). More sensitive to dye concentration are spec-
tra of excitation of fluorescence. It easily can be seen 
from Fig.1,a that even for N  0.5 mas. % strong widen-
ing of the band is observed in the spectrum of excita-
tion as compare to the same one in absorption spec-
trum. Moreover, in the first case the band possesses 
two maximums.  
Growth of An5 concentration effects in appearance 
of new long wavelength band in the fluorescence spec-
trum (Fig. 1, b). The fluorescence spectrum of FPC be-
comes dependent on light wavelength of excitation. The 
maximal respective intensity of the long wavelength 
band of fluorescence was observed upon excitation in 
short wavelength edge of absorption band (400 – 
440 nm). Increase of light wavelength of excitation re-
sults in growth of intensity of short wavelength band of 
fluorescence. The similar tendencies upon growth of 
An5 concentration were observed in FPC based on 
PVB.  
Described effects in the spectra of excitation and 
fluorescence of FPC are evidence of inhomogeneous 
widening of absorption band due to superposition of the 
bands from different dye forms. In concentrated poly-
meric solutions those forms are dye monomers and 
their associates. The polymethine dyes are able to cre-
ate associates of “sandwich”  structure [11]. In low po-
lar media “sandwiches” appear due to fixation of chro-
mophores from both ends by electrostatic forces of at-
traction of contact ionic pairs. Upon formation of asso-
ciates of “sandwich” structure the maximal splitting of 
the level of the first excited state (S1) of the monomers 
with higher (S1h) and lower (S1l) energy is reached [11]. 
Bathochrome shift of An5 luminescence band is evi-
dence of energy reduction. This reduction involves con-
vergence of HOMO energies of dye and PEPC. That can 
effect in possibility of electron transfer from PEPC to 
dye aggregate. Conditions for appearance of non-
equilibrium charge carriers arise. 
Appearance of non-equilibrium charge carriers can 
happen due to photostimulated electron transfer from 
anion (An ) to cation (Ct+) in contact ionic pairs. Upon 
dye excitation anion turn into S1 state of (An )1. Pres-
ence of non-paired electrons creates conditions for 
higher reaction ability as compare to the state S0. Pos-
sibility of such mechanism is confirmed by quantum-
chemical calculations. Upon formation of neutral radi-
cal (An5•) HOMO energy decreases until –6.0138 eV. 
This value is lower than HOMO of N-methilcarbazole 
 INTERNAL PHOTOEFFECT IN FILMS OF POLY … PROC. NAP 1, 04NEA06 (2012) 
 
 
04NEA06-3 
(–5.3280 eV). Thus, the radical An5• can play role of 
effective acceptor of electron from carbazole fragment of 
PEPC. It can create positive charge carrier – hole.  
Effect of FPC photoconductivity on the light wave-
length 2 also is unusual. The matter is, that 2 is out-
side the absorption band of An5 monomer. Therefore, 
irradiation of He-Ne laser can not involve inner photo-
effect in FPC. Unusual is also kinetics of the photocur-
rent jPH(t) (Fig. 2, c and Fig. 2, d) with slow growth of 
photocurrent and quite quick its relaxation when illu-
mination is ceased. The kinetics of photocurrent is the 
same for different values U and I. 
Addition of conductivity current jPH1 and jPH2 for 
stationary dark conductivity current is similar to kinet-
ics of jPH change. 
 
 
 
Fig. 1 – Normalized absorption spectrum (1), fluorescence spectra (2, 3) and fluorescence excitation (4) in FPC with 0.5 mas.  
An5 for irr  400 nm (2), 520 nm (3), 640 nm (4) (a); normalized spectrum of absorption (1), spectra of fluorescence (2, 3, 4) and 
excitation of fluorescence (5, 6) in FPC with 10 mas.  An5 for irr  440 nm (2), 520 nm (3), 560 nm (4) and light wavelengthof 
fluorescence registration 650 nm (5), 750 nm (6) (b); δDE dependencies on  in FPC based on PEPC with N  1.0 (1), 2 (2), 5 (3), 10 
(4) mas.  An5 (c) and dependencies of δIE on  in FPC based on PEPC with N  0.5 (1), 1 (2), 2 (3), 5 (4), 10 (5) mas.  An5 (d)  
 
 
 
Fig. 2 – Diagrams explaining the technique of measurements of jPH1 depending on time of delay t1 of electric field application after 
start of illumination of the samples with light (a), Diagrams explaining method of change of jPH2 depending on time interval t2 of 
delay of application of electric field after illumination is ceased (b), kinetics of photocurrents jPH and jPH1 for t1  45, 120, 215 s (c) 
and kinetics of photocurrents jPH and jPH2 for t2  5, 45, 60 s (d) 
 
 
 
 E.V. MOKRINSKAYA, S.L. STUDZINSKY PROC. NAP 1, 04NEA06 (2012) 
 
 
 04NEA06-4  
4. CONCLUSIONS 
 
Investigations of spectral-luminescent, electrocon-
ducting and photoconducting properties of the films of 
polymeric composites with different concentrations of 
anion polymethine dye are carried out. Influence of ex-
ternal electric field on spectra of absorption and photo-
luminescence, electric and photoconductivity of PEPC 
films doped with anion dye is studied. Widening of ab-
sorption and photoluminescence bands, quenching of 
photoluminescence intensity, arising of photoconductivi-
ty effect within visible range of spectrum were observed 
upon growth of dye concentration. These effects can be 
explained by formation of associates of dye molecules. 
The reason of photoconductivity can be attributed to 
photogeneration and transport of charge carriers in the 
associates. 
 
 
REFERENCES 
 
1. N. Davidenko, A. Ishchenko, N. Kuvshynsky, Photonics of 
Molecular Semiconducting Composites Based on Organic 
Dyes [in Russian] (Kyiv: Naukova Dumka: 2005). 
2. N.A. Davidenko, N.A. Derevyanko, A.A. Ishchenko, 
S.L. Studzinsky, V.A. Pavlov, A.D. Chetyrkin, 
N.G. Chuprina, Opt. Spectrosc. 106 No2, 229 (2009). 
3. N.A. Davidenko, S.V. Dehtyarenko, Yu.P. Getmanchuk, 
A.A. Ishchenko, A.V. Kozinetz, L.I. Kostenko, 
E.V. Mokrinskaya, S.L. Studzinskii, V.A. Skryshevskii, 
N.A. Skulskii, O.V. Tretyak, N.G. Chuprina, Semiconduc-
tors 43 No11, 1473 (2009). 
4. A.A. Ishchenko, G.P. Grabchuk, Theor. Exp. Chem. 45 
No3, 143 (2009). 
5. N.A. Davidenko, S.V. Dehtyarenko, A.V. Kozinetz, 
A.S. Lobach, E.V. Mokrinskaya, V.A. Skryshevsky, 
N.G. Spitsyna, S.L. Studzinsky, O.V. Tretyak, 
L.S. Tonkopiyeva, Tech. Phys. 56 No2, 259 (2011). 
6. Physics of Organic Semiconductors (Ed. V. Brutting) 
(Weinheim: WILEY-VCH Verlag GmbH & Co. KGaA: 
2005). 
7. N.A. Davidenko, V.A. Skryshevsky, A.A. Ishchenko, 
A.Yu. Karlash, E.V. Mokrinskaya, Semiconductors 43 
No5, 640 (2009). 
8. R. Naaman, D.N. Beratan, D.H. Waldeck, Electronic and 
Magnetic Properties of Chiral Molecules and Supramolecu-
lar Architectures (London - New York: Springer: 2011). 
9. Photophysics of Molecular Materials (Ed. G. Lanzani) 
(Weinheim: WILEY-VCH Verlag GmbH & Co. KGaA: 
2006). 
10. V. Agranovich, Thin Films and Nanostructures (Electronic 
Excitations in Organic Based Nanostructures, Volume 31) 
(New York: Elsevier Academic Press: 2003). 
11. A. Ishchenko, Structure and Spectral-Luminescent Proper-
ties of Polymethine Dyes (Kyiv: Naukova Dumka: 1994) (in 
Russian). 
12. N.A. Davidenko, M.A. Zabolotny, A.A. Ishchenko, Spectro-
chim. Acta A, 61, 213 (2005). 
13. http://classic.chem.msu.su/gran/firefly/index.html. 
14. N.A. Davidenko, N.A. Derevyanko, A.A. Ishchenko, 
S.L. Studzinsky, Theor. Exp. Chem. 44 No6, 351 (2008). 
 


English

Internal Photoeffect in Films of Poly-N-Epoxypropylcarbazole with High Concentration of Anion Polymethine Dye

Electronic Sumy State University Institutional Repository

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE NANOMATERIALS: APPLICATIONS AND PROPERTIES Vol. 1 No 4, 04NEA06(4pp) (2012)   2304-1862/2012/1(4)04NEA06(6) 04NEA06-1  2012 Sumy State University Internal Photoeffect in Films of Poly-N-Epoxypropylcarbazole with High Concentration of Anion Polymethine Dye  E.V. Mokrinskaya1,* , S.L. Studzinsky1,†, N.A. Davidenko1,‡, I.I. Davidenko1, A.A. Ishchenko2, G.P. Grabchuk2, L.S. Tonkopieva1  1 Kiev Taras Shevchenko National University, Volodymyrs’ka Str., 64, 01601 Kyiv. Ukraine 2 Institute of Organic Chemistry NAS of Ukraine, Murmans’ka Str., 5, 02094 Kyiv, Ukraine  (Received 12 June 2012; revised manuscript received 05 July 2012; published online 22 August 2012)  Growth of concentration of the anion polymethine dye in the films of poly-N-epoxypropylcarbazole in-volves increase of quenching of photoluminescence in external electric field as well as appearance of long-wave band of the photoluminescence and photoconductivity within visible spectral range. It was ascer-tained that associates of ionic pairs of the dye arise when the concentration increases. Anomalous for semi-conductor materials kinetics of the photocurrent growth and relaxation was observed in the films of these composites: time of the photocurrent growth is much less than the time of its relaxation after the light is switched off. Effect of memory of preliminary illumination with light was observed in the films.  Keywords: Photoconducting Polymers, Dyes, Spectra of Adsorption and Fluorescence, Associates, Kinetics of Photoconductivity, Recombination Centers.   PACS numbers: 73.50.Pz, 73.50.Gr, 78.55.Qr, 78.66.Sq                                                             * mokrinskaya@ukr.net † studzs@mail.ru ‡ ndav@univ.kiev.ua 1. INTRODUCTION  The films of polymeric composites (FPC) doped with organic dyes are commonly used in informatic record-ing and electroluminescent media as well as in photoe-lectric converters of solar energy [1 – 5]. In FPC mono-meric dye molecules play role of centers of light absorp-tion and photogeneration of non-equilibrium charge carriers. Considerable progress is reached in control of photophysical and electrophysical properties of FPC by adjustment of chemical structure of the dye and poly-mer. But these properties also depend on geometric size of FPC components [6-10]. Such dependency is caused by transformation of energetic structure of dopants which are in polymeric matrix. Thus, there is scientific and practical interest on development of new photoac-tive media based on FPC where inner photoeffect is realized due to size effects in dopants. The polymethine dyes [11] are the most interesting amongst organic dyes for application for light energy conversion. The work is aimed in investigation of photoelectric and spectral-luminescent properties of the films of polymeric compo-sites with high concentration of organic dye.  2. THE SAMPLES AND  EXPERIMENTAL TECHNIQUE  Poly-N-epoxypropylcarbazole (PEPC) and anionic dye An5 were used as FPC components. For compari-son the same dye was used in FPC based on non-photoconducting polyvinylbutyrale (PVB). The samples were prepared as the structures with free surface [glass substrate – electroconducting layer SnO2 : In2O3 – FPC] and sandwich-structures [glass substrate – electroconducting layer SnO2: In2O3 – FPC – Ag]. Concentration (N) of An5 was 0.5 – 10 mas. , FPC thickness was 1 – 1.5 m.    The technique of measurement of optical density (D), photoluminescence intensity (IL) within the range   400 – 900 nm, density (jPH) of photocurrent is de-scribed in [2, 12]. Green laser with maximum of irradi-ation at 1  532 nm and He-Ne laser with 2  633 nm were used for excitation of photoluminescence and for investigation of photoconducting properties of FPC. The values D and IL were measured before and after appli-cation of external electric field with strength Е  108 V/m. Parameters δDE  (DE – D0)/D0 and δILE   (ILE – IL0)/IL0, where D0 and IL0 are the values D and IL before application of the field (E), DE and ILE are the values D and IL after application of the field, were calculated using experimental results. Light intensity (I) at 1 and 2 was changed by neutral light filters within the range 1 – 50 W/m2. The value of electric voltage (U) which was applied to electric contacts in the samples of sandwich-structure was changed within the range 1 – 200 V. For measurements of fluorescence spectra and for excitation of fluorescence in FPC spec-tral fluorometer Solar CM2203 was used. All meas-urements were done at room temperature which corre-sponds to conditions of FPC practical applications.  E.V. MOKRINSKAYA, S.L. STUDZINSKY, N.A. Davidenko, ET AL. PROC. NAP 1, 04NEA06 (2012)   04NEA06-2 Quantum-chemical calculations of molecules N-methylcarbazole (as a model monomer of PEPC) and anion An5 were done by non-empirical method DFT/B3LYP in 6-31G(d,p) basis using program package PC Gamess/Firefly [13].  3. EXPERIMENTAL RESULTS AND DISCUS-SION  In the samples of sandwich-structure based on PEPC with N < 5 mas. % An5 photocurrent was not observed. In the samples with N > 5 mas. % An5 photo-current was observed both for  λ1 and for λ2. In the samples with N = 10 mas. % An5 for U = 100 V, I = 50 W/m2 the value jPH is 10-3 А/m2 under illumination with light with λ1 and 2·10-4 А/m2 under illumination with light with λ2. In the similar structures with PVB photo-current was not observed. Dependencies jPH on U can be described by analytical function jPH  UmPH, which is usually used for analysis of currents in semiconductor materials. Power exponent mPH  2.1 for 1 and 1.4 for 2. The value jPH does not depend on polarity U. The dependencies of jPH on I with λ1 and λ2 are close to line-ar. The last fact means that effect of photoconductivity which is not caused by two-quantum processes was discovered.   Discovered in the work photoeffect is unusual. It can not be explained by formation of electron-hole pairs (EHP) caused by electron transfer from carbazole frag-ment PEPC to excited molecule An5 due to difference HOMO energy (HOMO energy of the polymer which was calculated for N-methylcarbazole is –5.3280 еV and it is –2.2205 eV for An5 anion).  Additional investigations were carried out for deter-mination of reasons of appearance of inner photoeffect upon growth of An5 concentration. Influence of external electric field on spectra of absorption and photolumines-cence was observed in all investigated samples based on PEPC (Fig. 1).  When electric field is switched on the values D0 and IL0 reach the values DE and ILE during time interval  1 s, which is close to time of electric charge of geometric capacity of the sample. After electric field switching off all changes of spectra stop. Peculiarities of spectra changes depend on dye concentration. In FPC with N  5 mas.  when electric field is switched off within short wavelength range absorption intensity increases (δDE  0), intensity of photoluminescence decreases (δILE  0). Within the long wavelength range the effects are opposite (δDE  0, δILE  0) (Fig. 1, c). Earlier [2, 14] the similar changes were observed in photoconducting and non-photoconducting FPC with low concentration of symmetric polymethine dyes. These changes were explained by intramolecular redistribution of electronic density under influence of external electric field. But we have ascertained that upon N growth the dependen-cy δDE ( ) does not change whereas the dependency δILE( ) essentially transforms. The last fact reveals itself in quenching of luminescence upon application of electric field (δILE  0) in FPC with N  5 mas. . This quenching increases upon N growth (Fig. 1, d). That corresponds to the model considerations described in [1, 2]. Luminescence quenching of organic dyes in pho-toconducting FPC under electric field influence is ex-plained by formation and dissociation of EHP, namely by decrease of probability of radiative recombination of EHP. One can suppose, that increase of An5 concentration in PEPC involves appearance of aggregates of dye mol-ecules. But attributes of aggregation of An5 anion in FPC absorption spectra are absent. N growth involves appearance of new bands in absorption spectrum but shape of the curve changes weakly. Universal for or-ganic dye outline of long wavelength absorption band preserves its original appearance [11]. Characteristic attributes of association are absent in photolumines-cence spectrum for N  0.5 mas.  as well. Photolumi-nescence band does not depend on light wavelength of excitation and it is inversely similar to absorption band (Fig. 1, a). More sensitive to dye concentration are spec-tra of excitation of fluorescence. It easily can be seen from Fig.1,a that even for N  0.5 mas. % strong widen-ing of the band is observed in the spectrum of excita-tion as compare to the same one in absorption spec-trum. Moreover, in the first case the band possesses two maximums.  Growth of An5 concentration effects in appearance of new long wavelength band in the fluorescence spec-trum (Fig. 1, b). The fluorescence spectrum of FPC be-comes dependent on light wavelength of excitation. The maximal respective intensity of the long wavelength band of fluorescence was observed upon excitation in short wavelength edge of absorption band (400 – 440 nm). Increase of light wavelength of excitation re-sults in growth of intensity of short wavelength band of fluorescence. The similar tendencies upon growth of An5 concentration were observed in FPC based on PVB.  Described effects in the spectra of excitation and fluorescence of FPC are evidence of inhomogeneous widening of absorption band due to superposition of the bands from different dye forms. In concentrated poly-meric solutions those forms are dye monomers and their associates. The polymethine dyes are able to cre-ate associates of “sandwich”  structure [11]. In low po-lar media “sandwiches” appear due to fixation of chro-mophores from both ends by electrostatic forces of at-traction of contact ionic pairs. Upon formation of asso-ciates of “sandwich” structure the maximal splitting of the level of the first excited state (S1) of the monomers with higher (S1h) and lower (S1l) energy is reached [11]. Bathochrome shift of An5 luminescence band is evi-dence of energy reduction. This reduction involves con-vergence of HOMO energies of dye and PEPC. That can effect in possibility of electron transfer from PEPC to dye aggregate. Conditions for appearance of non-equilibrium charge carriers arise. Appearance of non-equilibrium charge carriers can happen due to photostimulated electron transfer from anion (An ) to cation (Ct+) in contact ionic pairs. Upon dye excitation anion turn into S1 state of (An )1. Pres-ence of non-paired electrons creates conditions for higher reaction ability as compare to the state S0. Pos-sibility of such mechanism is confirmed by quantum-chemical calculations. Upon formation of neutral radi-cal (An5•) HOMO energy decreases until –6.0138 eV. This value is lower than HOMO of N-methilcarbazole  INTERNAL PHOTOEFFECT IN FILMS OF POLY … PROC. NAP 1, 04NEA06 (2012)   04NEA06-3 (–5.3280 eV). Thus, the radical An5• can play role of effective acceptor of electron from carbazole fragment of PEPC. It can create positive charge carrier – hole.  Effect of FPC photoconductivity on the light wave-length 2 also is unusual. The matter is, that 2 is out-side the absorption band of An5 monomer. Therefore, irradiation of He-Ne laser can not involve inner photo-effect in FPC. Unusual is also kinetics of the photocur-rent jPH(t) (Fig. 2, c and Fig. 2, d) with slow growth of photocurrent and quite quick its relaxation when illu-mination is ceased. The kinetics of photocurrent is the same for different values U and I. Addition of conductivity current jPH1 and jPH2 for stationary dark conductivity current is similar to kinet-ics of jPH change.    Fig. 1 – Normalized absorption spectrum (1), fluorescence spectra (2, 3) and fluorescence excitation (4) in FPC with 0.5 mas.  An5 for irr  400 nm (2), 520 nm (3), 640 nm (4) (a); normalized spectrum of absorption (1), spectra of fluorescence (2, 3, 4) and excitation of fluorescence (5, 6) in FPC with 10 mas.  An5 for irr  440 nm (2), 520 nm (3), 560 nm (4) and light wavelengthof fluorescence registration 650 nm (5), 750 nm (6) (b); δDE dependencies on  in FPC based on PEPC with N  1.0 (1), 2 (2), 5 (3), 10 (4) mas.  An5 (c) and dependencies of δIE on  in FPC based on PEPC with N  0.5 (1), 1 (2), 2 (3), 5 (4), 10 (5) mas.  An5 (d)     Fig. 2 – Diagrams explaining the technique of measurements of jPH1 depending on time of delay t1 of electric field application after start of illumination of the samples with light (a), Diagrams explaining method of change of jPH2 depending on time interval t2 of delay of application of electric field after illumination is ceased (b), kinetics of photocurrents jPH and jPH1 for t1  45, 120, 215 s (c) and kinetics of photocurrents jPH and jPH2 for t2  5, 45, 60 s (d)     E.V. MOKRINSKAYA, S.L. STUDZINSKY PROC. NAP 1, 04NEA06 (2012)    04NEA06-4  4. CONCLUSIONS  Investigations of spectral-luminescent, electrocon-ducting and photoconducting properties of the films of polymeric composites with different concentrations of anion polymethine dye are carried out. Influence of ex-ternal electric field on spectra of absorption and photo-luminescence, electric and photoconductivity of PEPC films doped with anion dye is studied. Widening of ab-sorption and photoluminescence bands, quenching of photoluminescence intensity, arising of photoconductivi-ty effect within visible range of spectrum were observed upon growth of dye concentration. These effects can be explained by formation of associates of dye molecules. The reason of photoconductivity can be attributed to photogeneration and transport of charge carriers in the associates.   REFERENCES  1. N. Davidenko, A. Ishchenko, N. Kuvshynsky, Photonics of Molecular Semiconducting Composites Based on Organic Dyes [in Russian] (Kyiv: Naukova Dumka: 2005). 2. N.A. Davidenko, N.A. Derevyanko, A.A. Ishchenko, S.L. Studzinsky, V.A. Pavlov, A.D. Chetyrkin, N.G. Chuprina, Opt. Spectrosc. 106 No2, 229 (2009). 3. N.A. Davidenko, S.V. Dehtyarenko, Yu.P. Getmanchuk, A.A. Ishchenko, A.V. Kozinetz, L.I. Kostenko, E.V. Mokrinskaya, S.L. Studzinskii, V.A. Skryshevskii, N.A. Skulskii, O.V. Tretyak, N.G. Chuprina, Semiconduc-tors 43 No11, 1473 (2009). 4. A.A. Ishchenko, G.P. Grabchuk, Theor. Exp. Chem. 45 No3, 143 (2009). 5. N.A. Davidenko, S.V. Dehtyarenko, A.V. Kozinetz, A.S. Lobach, E.V. Mokrinskaya, V.A. Skryshevsky, N.G. Spitsyna, S.L. Studzinsky, O.V. Tretyak, L.S. Tonkopiyeva, Tech. Phys. 56 No2, 259 (2011). 6. Physics of Organic Semiconductors (Ed. V. Brutting) (Weinheim: WILEY-VCH Verlag GmbH & Co. KGaA: 2005). 7. N.A. Davidenko, V.A. Skryshevsky, A.A. Ishchenko, A.Yu. Karlash, E.V. Mokrinskaya, Semiconductors 43 No5, 640 (2009). 8. R. Naaman, D.N. Beratan, D.H. Waldeck, Electronic and Magnetic Properties of Chiral Molecules and Supramolecu-lar Architectures (London - New York: Springer: 2011). 9. Photophysics of Molecular Materials (Ed. G. Lanzani) (Weinheim: WILEY-VCH Verlag GmbH & Co. KGaA: 2006). 10. V. Agranovich, Thin Films and Nanostructures (Electronic Excitations in Organic Based Nanostructures, Volume 31) (New York: Elsevier Academic Press: 2003). 11. A. Ishchenko, Structure and Spectral-Luminescent Proper-ties of Polymethine Dyes (Kyiv: Naukova Dumka: 1994) (in Russian). 12. N.A. Davidenko, M.A. Zabolotny, A.A. Ishchenko, Spectro-chim. Acta A, 61, 213 (2005). 13. http://classic.chem.msu.su/gran/firefly/index.html. 14. N.A. Davidenko, N.A. Derevyanko, A.A. Ishchenko, S.L. Studzinsky, Theor. Exp. Chem. 44 No6, 351 (2008).  

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Internal Photoeffect in Films of Poly-N-Epoxypropylcarbazole with High Concentration of Anion Polymethine Dye

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