Controllable molecular doping and charge transport in solution-processed polymer semiconducting layers
article
Here, controlled p-type doping of poly(2-methoxy-5-(20-ethylhexyloxy)- pphenylene vinylene) (MEH-PPV) deposited from solution using tetrafluorotetracyanoquinodimethane (F4-TCNQ) as a dopant is presented. By using a co-solvent, aggregation in solution can be prevented and doped films can be deposited. Upon doping the current-voltage characteristics of MEH-PPVbased hole-only devices are increased by several orders of magnitude and a clear Ohmic behavior is observed at low bias. Taking the density dependence of the hole mobility into account the free hole concentration due to doping can be derived. It is found that a molar doping ratio of 1 F4-TCNQ dopant per 600 repeat units of MEH-PPV leads to a free carrier density of 441022m 3. Neglecting the density-dependent mobility would lead to an overestimation of the free hole density by an order of magnitude. The free hole densities are further confirmed by impedance measurements on Schottky diodes based on F4-TCNQ doped MEH-PPV and a silver electrode. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA.
Topics
Charge transportCosolventDensity dependenceDensity-dependentDoped filmsF4-TCNQFree carrier densityFree hole concentrationFree hole densityHole-only deviceImpedance measurementLow biasMEH-PPVMethoxyMolecular dopingOhmic behaviorOrder of magnitudeOrders of magnitudeP-phenylene vinyleneP-type dopingSchottky diodesSemiconducting layerSilver electrodeSolution-processed polymerTetrafluoro-tetracyanoquinodimethaneCurrent voltage characteristicsHole concentrationHole mobilitySchottky barrier diodesSilverDoping (additives)
TNO Identifier
461661
ISSN
1616301X
Source
Advanced Functional Materials, 19(12), pp. 1901-1905.
Pages
1901-1905
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