Interface electronic structure of organic semiconductors with controlled doping levels

Blochwitz, Jan; Fritz, Torsten; Pfeiffer, Martin; Leo, Karl; Alloway, Dana M.; Lee, P.A.; Armstrong, Neal R.

doi:10.1016/s1566-1199(01)00016-7

Cited by 255 publications

(197 citation statements)

References 36 publications

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“…[1][2][3][4] Conceptually, p-doping is realized by charge transfer from the highest occupied molecular orbital (HOMO) of the host material to the lowest unoccupied molecular orbital (LUMO) of the dopant. For a one-electron oxidizer, this charge transfer becomes energetically favorable when the electron affinity (EA) of the dopant is about equal to, or is larger than, the ionization energy (IE) of the host.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the High Electron Affinity Molecular Dopant F6‐TCNNQ for Hole‐Transport Materials

Zhang

Kahn

2017

Adv Funct Materials

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2,2′-(perfluoronaphthalene-2,6-diylidene)dimalononitrile (F6-TCNNQ) is investigated as a molecular p-type dopant in two hole-transport materials, 2,2′,7,7′-tetrakis(N,N-diphenylamino)-9,9-spirobifluorene (Spiro-TAD) and tris(4-carbazoyl-9-ylphenyl)amine (TCTA). The electron affinity of F6-TCNNQ is determined to be 5.60 eV, one of the strongest organic molecular oxidizing agents used to date in organic electronics. p-Doping is found to be effective in Spiro-TAD (ionization energy = 5.46 eV) but not in TCTA (ionization energy = 5.85 eV). Optical absorption measurements demonstrate that charge transfer is the predominant doping mechanism in Spiro-TAD:F6-TCNNQ. The hostdopant interaction also leads to a significant alteration of the host film morphology. Finally, transport measurements done on Spiro-TAD:F6-TCNNQ as a function of dopant concentration and temperature, and using a highly doped contact layer to ensure negligible hole injection barrier, lead to an accurate measurement of the film conductivity and hole-hopping activation energy.

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Section: Introductionmentioning

confidence: 99%

Investigation of the High Electron Affinity Molecular Dopant F6‐TCNNQ for Hole‐Transport Materials

Zhang

Kahn

2017

Adv Funct Materials

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“…Doping changes the charge carrier concentration 17 and width of depletion regions. 18 Furthermore, one obtains a barrier-free transport until the charge carriers reach the IIL. 19 In contrast, the IIL acts as an additional depletion layer and the voltage drop over the pin-junction mainly occurs in this intrinsic layer.…”

mentioning

confidence: 99%

Organic Zener Diodes: Tunneling across the Gap in Organic Semiconductor Materials

Kleemann

Gutiérrez²,

Lindner

et al. 2010

Nano Lett.

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Organic Zener diodes with a precisely adjustable reverse breakdown from -3 to -15 V without any influence on the forward current-voltage curve are realized. This is accomplished by controlling the width of the charge depletion zone in a pin-diode with an accuracy of one nanometer independently of the doping concentration and the thickness of the intrinsic layer. The breakdown effect with its exponential current voltage behavior and a weak temperature dependence is explained by a tunneling mechanism across the highest occupied molecular orbital-lowest unoccupied molecular orbital gap of neighboring molecules. The experimental data are confirmed by a minimal Hamiltonian model approach, including coherent tunneling and incoherent hopping processes as possible charge transport pathways through the effective device region.

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“…The OLEDs are being competitively developed globally for large displays [13,14]. The large organic light-emitting display is rapidly developing, and it will be soon a current display around us [15,16].…”

Section: Introductionmentioning

confidence: 99%

Performance Enhancement of Organic Light–Emitting Diodes Using Electron–Injection Materials of Metal Carbonates

Shin

Kim

et al. 2016

Journal of Electrical Engineering

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Performance of organic light-emitting diodes was investigated depending on the electron-injection materials of metal carbonates ( Li 2 CO 3 and Cs 2 CO 3 ); and number of layers. In order to improve the device efficiency, two types of devices were manufactured by using the hole-injection material (Teflon-amorphous fluoropolymer -AF) and electron-injection materials; one is a two-layer reference device ( ITO/Teflon-AF/Alq 3 /Al ) and the other is a three-layer device (ITO/Teflon-AF/Alq 3 / metal carbonate/Al). From the results of the efficiency for the devices with hole-injection layer and electroninjection layer, it was found that the electron-injection layer affects the electrical properties of the device more than the hole-injection layer. The external-quantum efficiency for the three-layer device with Li 2 CO 3 and Cs 2 CO 3 layer is improved by approximately six and eight times, respectively, compared with that of the two-layer reference device. It is thought that a use of electron-injection layer increases recombination rate of charge carriers by the active injection of electrons and the blocking of holes.K e y w o r d s: organic light-emitting diodes, electron-injection materials, metal carbonates, Li 2 CO 3 , Cs 2 CO 3

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Interface electronic structure of organic semiconductors with controlled doping levels

Cited by 255 publications

References 36 publications

Investigation of the High Electron Affinity Molecular Dopant F6‐TCNNQ for Hole‐Transport Materials

Investigation of the High Electron Affinity Molecular Dopant F6‐TCNNQ for Hole‐Transport Materials

Organic Zener Diodes: Tunneling across the Gap in Organic Semiconductor Materials

Performance Enhancement of Organic Light–Emitting Diodes Using Electron–Injection Materials of Metal Carbonates

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