Title
The effect of ketone defects on the charge transport and charge recombination in polyfluorenes
Author
Kuik, M.
Wetzelaer, G.-J.A.H.
Laddé, J.G.
Nicolai, H.T.
Wildeman, J.
Sweelssen, J.
Blom, P.W.M.
Publication year
2011
Abstract
The effect of on-chain ketone defects on the charge transport of the polyfluorene derivative poly(9,9-dioctylfluorene) (PFO) is investigated. Using MoO3 as ohmic hole contact, the hole transport in a pristine PFO diode is observed to be limited by space-charge, whereas fluorenone contaminated PFO (PFO-F) is shown to be trap limited by the occurrence of an exponential trap distribution with a trap depth of 0.18 eV. The electron transport in PFO is also observed to be trap limited, but in order to describe the electron transport of PFO-F, an additional trap level with a depth of 0.46 eV must be introduced. The obtained energy levels of the fluorenone trapping sites are in close agreement with cyclic voltammetry (CV) measurements reported in literature. As a result, the fluorenone defects are shown to simultaneously act as hole- and electron trap. Moreover, through ideality factor measurements, the green emission associated with these defects is observed to originate from trap-assisted recombination. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Subject
Mechatronics, Mechanics & Materials
HOL - Holst MIP - Materials for Integrated Products
TS - Technical Sciences
Materials
Industrial Innovation
characterization tools
conjugated polymers
organic electronics
organic light-emitting diodes
Charge recombinations
Electron transport
Exponential trap distribution
Fluorenone defect
Fluorenones
Green emissions
Hole transports
Ideality factors
organic electronics
Poly(9 ,9-dioctylfluorene)
Polyfluorene derivative
Polyfluorenes
Space charges
Trap depth
Trap levels
Trapping sites
Conjugated polymers
Cyclic voltammetry
Defects
Electron transitions
Electron transport properties
Light emitting diodes
Molybdenum oxide
Organic compounds
Ketones
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http://resolver.tudelft.nl/uuid:5a75d84b-c9ed-43f8-b2e5-e7d4fdfcf218
TNO identifier
445707
ISSN
1616-301X
Source
Advanced Functional Materials, 21 (23), 4502-4509
Document type
article