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Proceedings Paper

Influence of polymer:sensitizer ratio on photoelectric properties of organic composite photoconductor
Author(s): K. Aleman; A. Sanchez Juarez; A. Kosarev; S. Mansurova; S. Koeber; K. Meerholz
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Paper Abstract

The results on characterization of the main photoelectric properties of the polymer:fulleren based composite material by using the non-steady-state photo-electromotive force (p-EMF) and modulated photocurrent technique are presented. By measuring this current under different experimental conditions, important material photoelectric parameters such as drift L0 and diffusion length LD, photocarrier's lifetime τ ; quantum efficiency of charge generation φ can be determined. The 50% of the composite weight consists of a mixture of the hole-conducting polymer PF6:TPD (poly-hexyle-triophene:N,N'-bis(4-methylphenyl)-N,N'-bis-(phenyl)-benzidine) sensitized with the highly soluble C60 derivative PCBM (phenyl-C61-butyric acid methyl ester) . Seven samples with varied polymer:sensitizer weight ratio (49:1wt.-%, 45:5wt.-%, 40:10wt.-%, 15:35wt.-%, 25:25wt.-%, 10:40wt.-%, 5:45wt.-%) where prepared. The remaining 50% were two azo-dyes 2,5-dimethyl-(4-p-nitrophenylazo)-anisole (DMNPAA) and 3- methoxy-(4-p-nitrophenylazo)-anisole (MNPAA) (25wt.-% each). Photoconductive composite film was sandwiched between two glass plates covered by transparent ITO electrodes. Two counter-propagating beams derived from a cw HeNe laser (λ = 633nm) intersected inside the detector creating an interference pattern. The output photo-EMF current (SEE MANUSCRIPT FOR EQUATION) was detected as a voltage drop by a lock-in amplifier. At polymer sensitizer ratio 25:25wt.-% the signal sign changes to the opposite revealing that the majority carriers at this and higher concentration of sensitizer are electrons. Our results show that the majority carrier's lifetime τ is only slightly affected by the variations of sensitizer concentration. Mobility-lifetime product μhτh of holes, on its turn decreases at the increasing sensitizer concentration, while μeτe of electrons keeps increasing. All this indicates that the carrier's mobility is strongly influenced by the changes on sensitizer concentrations.

Paper Details

Date Published: 22 September 2010
PDF: 7 pages
Proc. SPIE 7750, Photonics North 2010, 77501W (22 September 2010); doi: 10.1117/12.876387
Show Author Affiliations
K. Aleman, Instituto Nacional de Astrofísica, Óptica y Electrónica (Mexico)
A. Sanchez Juarez, Instituto Nacional de Astrofísica, Óptica y Electrónica (Mexico)
A. Kosarev, Instituto Nacional de Astrofísica, Óptica y Electrónica (Mexico)
S. Mansurova, Instituto Nacional de Astrofísica, Óptica y Electrónica (Mexico)
S. Koeber, Univ. zu Köln (Germany)
K. Meerholz, Univ. zu Köln (Germany)

Published in SPIE Proceedings Vol. 7750:
Photonics North 2010
Henry P. Schriemer; Rafael N. Kleiman, Editor(s)

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