Modeling space-charge-limited currents in organic semiconductors: Extracting trap density and mobility

Handle URI:
http://hdl.handle.net/10754/598860
Title:
Modeling space-charge-limited currents in organic semiconductors: Extracting trap density and mobility
Authors:
Dacuña, Javier; Salleo, Alberto
Abstract:
We have developed and have applied a mobility edge model that takes drift and diffusion currents to characterize the space-charge-limited current in organic semiconductors into account. The numerical solution of the drift-diffusion equation allows the utilization of asymmetric contacts to describe the built-in potential within the device. The model has been applied to extract information of the distribution of traps from experimental current-voltage measurements of a rubrene single crystal from Krellner showing excellent agreement across several orders of magnitude in the current. Although the two contacts are made of the same metal, an energy offset of 580 meV between them, ascribed to differences in the deposition techniques (lamination vs evaporation) was essential to correctly interpret the shape of the current-voltage characteristics at low voltage. A band mobility of 0.13cm 2V-1s-1 for holes is estimated, which is consistent with transport along the long axis of the orthorhombic unit cell. The total density of traps deeper than 0.1 eV was 2.2×1016cm -3. The sensitivity analysis and error estimation in the obtained parameters show that it is not possible to accurately resolve the shape of the trap distribution for energies deeper than 0.3 eV or shallower than 0.1 eV above the valence-band edge. The total number of traps deeper than 0.3 eV, however, can be estimated. Contact asymmetry and the diffusion component of the current play an important role in the description of the device at low bias and are required to obtain reliable information about the distribution of deep traps. © 2011 American Physical Society.
Citation:
Dacuña J, Salleo A (2011) Modeling space-charge-limited currents in organic semiconductors: Extracting trap density and mobility. Physical Review B 84. Available: http://dx.doi.org/10.1103/PhysRevB.84.195209.
Publisher:
American Physical Society (APS)
Journal:
Physical Review B
KAUST Grant Number:
KUS-C1-015-21
Issue Date:
28-Nov-2011
DOI:
10.1103/PhysRevB.84.195209
Type:
Article
ISSN:
1098-0121; 1550-235X
Sponsors:
This paper was based on work supported by the Center for Advanced Molecular Photovoltaics (Award No. KUS-C1-015-21), made by King Abdullah University of Science and Technology (KAUST). J.D. also gratefully acknowledges funding from the "la Caixa" Foundation.
Appears in Collections:
Publications Acknowledging KAUST Support

Full metadata record

DC FieldValue Language
dc.contributor.authorDacuña, Javieren
dc.contributor.authorSalleo, Albertoen
dc.date.accessioned2016-02-25T13:42:36Zen
dc.date.available2016-02-25T13:42:36Zen
dc.date.issued2011-11-28en
dc.identifier.citationDacuña J, Salleo A (2011) Modeling space-charge-limited currents in organic semiconductors: Extracting trap density and mobility. Physical Review B 84. Available: http://dx.doi.org/10.1103/PhysRevB.84.195209.en
dc.identifier.issn1098-0121en
dc.identifier.issn1550-235Xen
dc.identifier.doi10.1103/PhysRevB.84.195209en
dc.identifier.urihttp://hdl.handle.net/10754/598860en
dc.description.abstractWe have developed and have applied a mobility edge model that takes drift and diffusion currents to characterize the space-charge-limited current in organic semiconductors into account. The numerical solution of the drift-diffusion equation allows the utilization of asymmetric contacts to describe the built-in potential within the device. The model has been applied to extract information of the distribution of traps from experimental current-voltage measurements of a rubrene single crystal from Krellner showing excellent agreement across several orders of magnitude in the current. Although the two contacts are made of the same metal, an energy offset of 580 meV between them, ascribed to differences in the deposition techniques (lamination vs evaporation) was essential to correctly interpret the shape of the current-voltage characteristics at low voltage. A band mobility of 0.13cm 2V-1s-1 for holes is estimated, which is consistent with transport along the long axis of the orthorhombic unit cell. The total density of traps deeper than 0.1 eV was 2.2×1016cm -3. The sensitivity analysis and error estimation in the obtained parameters show that it is not possible to accurately resolve the shape of the trap distribution for energies deeper than 0.3 eV or shallower than 0.1 eV above the valence-band edge. The total number of traps deeper than 0.3 eV, however, can be estimated. Contact asymmetry and the diffusion component of the current play an important role in the description of the device at low bias and are required to obtain reliable information about the distribution of deep traps. © 2011 American Physical Society.en
dc.description.sponsorshipThis paper was based on work supported by the Center for Advanced Molecular Photovoltaics (Award No. KUS-C1-015-21), made by King Abdullah University of Science and Technology (KAUST). J.D. also gratefully acknowledges funding from the "la Caixa" Foundation.en
dc.publisherAmerican Physical Society (APS)en
dc.titleModeling space-charge-limited currents in organic semiconductors: Extracting trap density and mobilityen
dc.typeArticleen
dc.identifier.journalPhysical Review Ben
dc.contributor.institutionStanford University, Palo Alto, United Statesen
kaust.grant.numberKUS-C1-015-21en
kaust.grant.fundedcenterCenter for Advanced Molecular Photovoltaics (CAMP)en
All Items in KAUST are protected by copyright, with all rights reserved, unless otherwise indicated.