Photoconductivity of synthetic dopa-melanin polymer.
The photoconductivity effect in synthetic dopa-melanin polymer with relation to the charge hopping conduction has been investigated. Measurements of the rise and decay of photocurrents upon visible radiation (400-800 nm) and at temperatures of 293-326 K allowed the determination of the major trapping levels as follows: 56, 35 and 26 kJ/mol. Spectral response of the steady-state photocurrent in the range 367-1100 nm showed significant departures from the absorption spectrum of melanin. The high concentration of traps or recombination centers can explain the long time-constants calculated from the photocurrent rise and decay curves. The results obtained can support the postulated earlier polarons and hopping model of conductivity in synthetic dopa-melanin.
Jastrzebska
M
M
Department of Biophysics, Faculty of Pharmacy, Medical University of Silesia, Ostrogórska 30, 41-200 Sosnowiec, Poland. maja@slam.katowice.pl
Kocot
A
A
Tajber
L
L
D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000528:radiation effects; D007700:Kinetics; D008027:Light; D010777:Photochemistry; D013816:Thermodynamics
D004295:Dihydroxyphenylalanine; C040616:DOPA melanin