Special Section on Organic Light-Emitting Materials and Devices

Electromodulated doping of the hole transport layer in a small molecule organic light-emitting diode

[+] Author Affiliations
Paul A. Lane

Naval Research Laboratory, 4555 Overlook Avenue S.W., Washington, DC 20375-5611

Song Chen, Franky So

University of Florida, Department of Materials Science and Engineering, Gainesville, Florida 35611

J. Photon. Energy. 1(1), 011020 (April 26, 2011). doi:10.1117/1.3569109
History: Received September 30, 2010; Revised January 26, 2011; Accepted March 01, 2011; Published April 26, 2011; Online April 26, 2011
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Electromodulation spectroscopy has been used to probe the effect of a polymer hole injection layer on electric fields and charge injection in vacuum-deposited organic light-emitting diodes. The electromodulation spectrum consists of electroabsorption of the transport layers and excited state absorption of trapped cations in the hole transport layer. Field-dependent modulation of trapped charge at the interface between the injection and transport layers substantially modifies the electric field distribution within the device. In reverse bias, the electric field strength is suppressed within the hole transport layer and concentrated in the electron transport layer. In forward bias, field-dependent doping of the hole transport layer dominates the electromodulation spectrum. The field-dependent trap density is calculated to be of order 1013 cm−2, equivalent to μC/cm2 charge density. The built-in potential is estimated to be between 2.2 and 2.5 V, consistent with low carrier injection barriers.

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© 2011 Society of Photo-Optical Instrumentation Engineers (SPIE)

Citation

Paul A. Lane ; Song Chen and Franky So
"Electromodulated doping of the hole transport layer in a small molecule organic light-emitting diode", J. Photon. Energy. 1(1), 011020 (April 26, 2011). ; http://dx.doi.org/10.1117/1.3569109


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