Electrical doping of poly(9,9-dioctylfluorenyl-2,7-diyl) with tetrafluorotetracyanoquinodimethane by solution method

Jaehyung Hwang; Antoine Kahn

doi:10.1063/1.1895470

Electrical doping of poly(9,9-dioctylfluorenyl-2,7-diyl) with tetrafluorotetracyanoquinodimethane by solution method

Jaehyung Hwang
, Antoine Kahn

Research output: Contribution to journal › Article › peer-review

41 Scopus citations

Abstract

We investigate p -type doping of poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) films with tetrafluorotetracyanoquinodimethane (F4 -TCNQ) introduced via cosolution. Doped and undoped films are compared using ultraviolet photoelectron spectroscopy (UPS) and current-voltage (I-V) measurement. In spite of the difference between the ionization energy of PFO (5.8 eV) and the electron affinity of F4 -TCNQ (5.24 eV), p doping occurs, as seen from the movement of the Fermi level (EF) toward the polymer highest occupied molecular orbital (HOMO). Interface hole barriers are measured for undoped and doped PFO deposited on three substrates with different work functions, indium-tin-oxide (ITO), gold (Au), and poly-3,4-ethylenedioxythiophene·polystyrenesulfonate (PEDOT·PSS). Doping leads to the formation of a depletion region at the PFO/ITO and PFOAu interfaces. The depletion region is believed to be at the origin of the (hole) current enhancement observed on simple metal/PFO/substrate devices.

Original language	English (US)
Article number	103705
Journal	Journal of Applied Physics
Volume	97
Issue number	10
DOIs	https://doi.org/10.1063/1.1895470
State	Published - May 15 2005

All Science Journal Classification (ASJC) codes

General Physics and Astronomy

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10.1063/1.1895470

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@article{0596048dfe7248d7a8f85ae1add4e073,

title = "Electrical doping of poly(9,9-dioctylfluorenyl-2,7-diyl) with tetrafluorotetracyanoquinodimethane by solution method",

abstract = "We investigate p -type doping of poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) films with tetrafluorotetracyanoquinodimethane (F4 -TCNQ) introduced via cosolution. Doped and undoped films are compared using ultraviolet photoelectron spectroscopy (UPS) and current-voltage (I-V) measurement. In spite of the difference between the ionization energy of PFO (5.8 eV) and the electron affinity of F4 -TCNQ (5.24 eV), p doping occurs, as seen from the movement of the Fermi level (EF) toward the polymer highest occupied molecular orbital (HOMO). Interface hole barriers are measured for undoped and doped PFO deposited on three substrates with different work functions, indium-tin-oxide (ITO), gold (Au), and poly-3,4-ethylenedioxythiophene·polystyrenesulfonate (PEDOT·PSS). Doping leads to the formation of a depletion region at the PFO/ITO and PFOAu interfaces. The depletion region is believed to be at the origin of the (hole) current enhancement observed on simple metal/PFO/substrate devices.",

author = "Jaehyung Hwang and Antoine Kahn",

note = "Funding Information: Funding for this work by the DOE (Grant No. DE-FG02-04ER46165), General Electric, and NEDO Japan is gratefully acknowledged. We also thank R. Holmes for help with optical absorption measurement. FIG. 1. Comparison of the electron affinity (EA) and ionization energy (IE) of PFO and F 4 - TCNQ. The chemical structures of the two compounds are shown below. FIG. 2. UPS spectra of (a) undoped(엯) and 1\% doped(●) PFO on ITO, (b) undoped(▵) and 1\% doped(▴) PFO on Au, and (c) undoped(▿) and 10\% doped(▾) PFO on PEDOT∙PSS. The left part of each plot shows the onset of photoemission. FIG. 3. Position of the molecular levels vs Fermi level for (a) undoped PFO/ITO and 1\% doped PFO/ITO and (b) undoped PFO ∕ Au and 1 \% doped ∕ Au . FIG. 4. E F - HOMO for different dopant concentrations in PFO on ITO(●), Au(▴), and PEDOT∙PSS(▾). FIG. 5. I – V characteristics for Au ∕ undoped PFO/ITO(엯), Au ∕ 10 \% doped PFO/ITO(●), and Au ∕ 10 \% doped PFO/ PEDOT∙PSS(▾). FIG. 6. Schematics of the thermionic emission and tunneling contributions to the current in (a) undoped PFO/ITO, (b) doped PFO/ITO, and (c) doped PFO/PEDOT∙PSS. ",

year = "2005",

month = may,

day = "15",

doi = "10.1063/1.1895470",

language = "English (US)",

volume = "97",

journal = "Journal of Applied Physics",

issn = "0021-8979",

publisher = "American Institute of Physics",

number = "10",

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TY - JOUR

T1 - Electrical doping of poly(9,9-dioctylfluorenyl-2,7-diyl) with tetrafluorotetracyanoquinodimethane by solution method

AU - Hwang, Jaehyung

AU - Kahn, Antoine

N1 - Funding Information: Funding for this work by the DOE (Grant No. DE-FG02-04ER46165), General Electric, and NEDO Japan is gratefully acknowledged. We also thank R. Holmes for help with optical absorption measurement. FIG. 1. Comparison of the electron affinity (EA) and ionization energy (IE) of PFO and F 4 - TCNQ. The chemical structures of the two compounds are shown below. FIG. 2. UPS spectra of (a) undoped(엯) and 1% doped(●) PFO on ITO, (b) undoped(▵) and 1% doped(▴) PFO on Au, and (c) undoped(▿) and 10% doped(▾) PFO on PEDOT∙PSS. The left part of each plot shows the onset of photoemission. FIG. 3. Position of the molecular levels vs Fermi level for (a) undoped PFO/ITO and 1% doped PFO/ITO and (b) undoped PFO ∕ Au and 1 % doped ∕ Au . FIG. 4. E F - HOMO for different dopant concentrations in PFO on ITO(●), Au(▴), and PEDOT∙PSS(▾). FIG. 5. I – V characteristics for Au ∕ undoped PFO/ITO(엯), Au ∕ 10 % doped PFO/ITO(●), and Au ∕ 10 % doped PFO/ PEDOT∙PSS(▾). FIG. 6. Schematics of the thermionic emission and tunneling contributions to the current in (a) undoped PFO/ITO, (b) doped PFO/ITO, and (c) doped PFO/PEDOT∙PSS.

PY - 2005/5/15

Y1 - 2005/5/15

N2 - We investigate p -type doping of poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) films with tetrafluorotetracyanoquinodimethane (F4 -TCNQ) introduced via cosolution. Doped and undoped films are compared using ultraviolet photoelectron spectroscopy (UPS) and current-voltage (I-V) measurement. In spite of the difference between the ionization energy of PFO (5.8 eV) and the electron affinity of F4 -TCNQ (5.24 eV), p doping occurs, as seen from the movement of the Fermi level (EF) toward the polymer highest occupied molecular orbital (HOMO). Interface hole barriers are measured for undoped and doped PFO deposited on three substrates with different work functions, indium-tin-oxide (ITO), gold (Au), and poly-3,4-ethylenedioxythiophene·polystyrenesulfonate (PEDOT·PSS). Doping leads to the formation of a depletion region at the PFO/ITO and PFOAu interfaces. The depletion region is believed to be at the origin of the (hole) current enhancement observed on simple metal/PFO/substrate devices.

AB - We investigate p -type doping of poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) films with tetrafluorotetracyanoquinodimethane (F4 -TCNQ) introduced via cosolution. Doped and undoped films are compared using ultraviolet photoelectron spectroscopy (UPS) and current-voltage (I-V) measurement. In spite of the difference between the ionization energy of PFO (5.8 eV) and the electron affinity of F4 -TCNQ (5.24 eV), p doping occurs, as seen from the movement of the Fermi level (EF) toward the polymer highest occupied molecular orbital (HOMO). Interface hole barriers are measured for undoped and doped PFO deposited on three substrates with different work functions, indium-tin-oxide (ITO), gold (Au), and poly-3,4-ethylenedioxythiophene·polystyrenesulfonate (PEDOT·PSS). Doping leads to the formation of a depletion region at the PFO/ITO and PFOAu interfaces. The depletion region is believed to be at the origin of the (hole) current enhancement observed on simple metal/PFO/substrate devices.

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U2 - 10.1063/1.1895470

DO - 10.1063/1.1895470

M3 - Article

AN - SCOPUS:20944436563

SN - 0021-8979

VL - 97

JO - Journal of Applied Physics

JF - Journal of Applied Physics

IS - 10

M1 - 103705

ER -

Electrical doping of poly(9,9-dioctylfluorenyl-2,7-diyl) with tetrafluorotetracyanoquinodimethane by solution method

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