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Electrically Detected Magnetic Resonance of MEH-PPV diodes

Published online by Cambridge University Press:  01 February 2011

George B. Silva ,
Lucas F. Santos ,
Roberto M. Faria  and
Carlos F. O. Graeff
George B. Silva
Affiliation:
Departamento de Física e Matemática-FFCLRP-USP, Av. Bandeirantes 3900, 14040-901 Ribeirão Preto, Brazil
Lucas F. Santos
Affiliation:
Instituto de Física de São Carlos-USP, C.P. 369, 13560-970 São Carlos, Brazil
Roberto M. Faria
Affiliation:
Instituto de Física de São Carlos-USP, C.P. 369, 13560-970 São Carlos, Brazil
Carlos F. O. Graeff
Affiliation:
Departamento de Física e Matemática-FFCLRP-USP, Av. Bandeirantes 3900, 14040-901 Ribeirão Preto, Brazil
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Abstract

In this work electrically detected magnetic resonance (EDMR) is used to study the electronic properties of poly(2-methoxy-5-(2'-ethyl-hexoxy)-1,4-phenylene vinylene) (MEHPPV) diodes. Two kinds of MEH-PPV diodes were characterized. The first one was a bipolar light emitting diode whose structure was ITO/MEH-PPV/Al. In this diode the EDMR signal is composed of two lines, a line that can be fitted by a lorentzian with peak-to-peak linewidth of 5.0 ± 0.5 G and the other best fitted with gaussian line with a linewidth of 24 ± 1 G. The g factor of both components is 2.002 ± 0.001 and signals were only observed at forward bias. The second diode is a hole only device, with a structure ITO/MEH-PPV/Au, the EDMR signal in this case is dominated by a gaussian line with peak-to-peak linewidth of 5 ± 1 G and average g factor of 2.0014 ± 0.0002. In high forward bias (V > 30 volts at T = 130K) a second line could be observed with a linewidth of 10 ± 2 G and a g factor of 2.0012 ± 0.0004. The signal from both types of diodes is quenching, and tipically10-5 in amplitude. The EDMR signal is assigned to the spin-dependent fusion of two like-charged polarons. Our results indicate that the narrower component is coming from positive polarons while the broader to negative polarons.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 725: Symposium P – Organic and Polymeric Materials and Devices-Optical, Electrical, and Optoelectronic Properties , 2002 , P4.18
Copyright
Copyright © Materials Research Society 2002

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