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Proceedings Paper

Absolute hole injection efficiency from pre-treated indium tin oxide electrodes into poly(9,9-dioctylflourene) and its copolymers
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Paper Abstract

If conduction in a polymer light emitting diode is by trap- free, space-charge-limited current (TFSCLC), the injecting contact must be ohmic. Such an ohmic contact is, by definition, the perfect injecting electrode. The absolute injection efficiency of any specific contact can therefore be quantified by the ratio of the actual current density, J, to that of the ideal TFSCLC current density, JTFSCLC. In this work we report on the injection efficiency of positive carriers from pretreated indium tin oxide (ITO) and metal electrodes into poly(9,9-dioctylfluorene) (PFO) and two representative copolymers. The ITO was either washed only in solvents, exposed to an oxygen plasma or coated in a film of poly(ethylenedioxythiophene)/polystyrenesulphonic acid blend. Time-of-flight photocurrent measurements were used to find the positive carrier mobility, (mu) p, so that JTFSCLC could be calculated. Dark injection current transient measurements were used to confirm the presence or absence of TFSCLC conduction. Steady-state, current density- voltage measurements were then used to compare the actual current to JTFSCLC, thus allowing the absolute injection efficiency, J/J(subscript TFSCLC, to be calculated.

Paper Details

Date Published: 2 February 2001
PDF: 16 pages
Proc. SPIE 4105, Organic Light-Emitting Materials and Devices IV, (2 February 2001); doi: 10.1117/12.416896
Show Author Affiliations
Alasdair J. Campbell, Univ. of Sheffield (United Kingdom)
Donal D. C. Bradley, Univ. of Sheffield (United Kingdom)
Homer Antoniadis, Infineon Technologies Corp. (United States)


Published in SPIE Proceedings Vol. 4105:
Organic Light-Emitting Materials and Devices IV
Zakya H. Kafafi, Editor(s)

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