1 January 2011 Electromodulated doping of the hole transport layer in a small molecule organic light-emitting diode
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J. of Photonics for Energy, 1(1), 011020 (2011). doi:10.1117/1.3569109
Abstract
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.
Paul A. Lane, Song Chen, Franky So, "Electromodulated doping of the hole transport layer in a small molecule organic light-emitting diode," Journal of Photonics for Energy 1(1), 011020 (1 January 2011). http://dx.doi.org/10.1117/1.3569109
Submission: Received ; Accepted
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KEYWORDS
Organic light emitting diodes

Absorption

Doping

Modulation

Molecules

Polymers

Interfaces

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