Electrical characteristics of light-emitting diode based on poly(p-phenylenevinylene) derivatives: CzEH-PPV and OxdEH-PPV

H. S. Kang; K. H. Kim; M. S. Kim; K. T. Park; K. M. Kim; T. H. Lee; C. Y. Lee; J. Joo; D. W. Lee; Y. R. Hong; K. Kim; G. J. Lee; J. I. Jin

doi:10.1016/S0379-6779(02)00126-1

Electrical characteristics of light-emitting diode based on poly(p-phenylenevinylene) derivatives: CzEH-PPV and OxdEH-PPV

H. S. Kang, K. H. Kim, M. S. Kim, K. T. Park, K. M. Kim, T. H. Lee, C. Y. Lee, J. Joo, D. W. Lee, Y. R. Hong, K. Kim, G. J. Lee, J. I. Jin

Department of Chemistry & Nanoscience

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

20 Scopus citations

Abstract

In the light-emitting devices (LEDs) based on the π-conjugated polymers, the relationship between the quantum efficiency and the balance of hole (μ_h) and electron (μ_e) mobility has been investigated. In order to measure the μ_h and μ_e of the LEDs based on π-conjugated polymers, we fabricated the hole transport device (HTD) and the electron transport device (ETD) by using various metal electrodes with different work functions. For the materials of light emitting layer, we synthesized poly[2-(N-carbazolyl)-5-(2-ethylhexyloxy)-1,4-phenylene vinylene] (CzEH-PPV) and poly[2-{4-[5-(4-tert-butylphenyl)-1,3,4-oxadiazolyl]-phenyl}-5-(2-ethylhexyloxy) -1,4-phenylenevinylene] (OxdEH-PPV) with electron-rich groups. The poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV), which is well known material for the polymer-based LED, was synthesized for the reference. We measured the current density vs. applied field (J-E) characteristics of the HTD and ETD with various thickness at different temperatures. The results of the J-E curves were analyzed by using the space charge limited conduction (SCLC) model. Based upon the SCLC model, μ_h and μ_e of MEH-PPV sample was measured to be ∼10^-6cm²/Vs and ∼10^-8cm²/Vs, respectively. For CzEH-PPV and OxdEH-PPV samples with electron-rich groups, μ_h was similar to μ_e with 10^-10-10^-11cm²/Vs. The μ_h and μ_e of CzEH-PPV and OxdEH-PPV samples was lower than that of MEH-PPV sample, but more balanced. The quantum efficiency of the LED by using CzEH-PPV or OxdEH-PPV materials was ∼10 times higher than that prepared from MEH-PPV. The balance of the μ_h and μ_e plays an important role for the quantum efficiency. We analyze the balance of the μ_h and μ_e and the relatively low mobilities of CzEH-PPV and OxdEH-PPV samples in terms of the heavier effective mass due to the asymmetric dipole distribution in the side chains. The results of photocurrent of the systems qualitatively agreed with the result of the electrical measurements. From AC impedance measurement of the LEDs, we observed that the relaxation time of MEH-PPV was shorter than that of OxdEH-PPV sample because of the higher mobility of MEH-PPV sample.

Original language	English
Pages (from-to)	279-283
Number of pages	5
Journal	Synthetic Metals
Volume	130
Issue number	3
DOIs	https://doi.org/10.1016/S0379-6779(02)00126-1
State	Published - 20 Oct 2002

Bibliographical note

Funding Information:
This work was supported in part by the CRM-KOSEF (2001).

Keywords

CzEH-PPV
Light-emitting diode
Mobility
OxdEH-PPV
Time of flight

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10.1016/S0379-6779(02)00126-1

Cite this

@article{e7ca4ded9adf4c359f2ae7a4461b964d,

title = "Electrical characteristics of light-emitting diode based on poly(p-phenylenevinylene) derivatives: CzEH-PPV and OxdEH-PPV",

abstract = "In the light-emitting devices (LEDs) based on the π-conjugated polymers, the relationship between the quantum efficiency and the balance of hole (μh) and electron (μe) mobility has been investigated. In order to measure the μh and μe of the LEDs based on π-conjugated polymers, we fabricated the hole transport device (HTD) and the electron transport device (ETD) by using various metal electrodes with different work functions. For the materials of light emitting layer, we synthesized poly[2-(N-carbazolyl)-5-(2-ethylhexyloxy)-1,4-phenylene vinylene] (CzEH-PPV) and poly[2-{4-[5-(4-tert-butylphenyl)-1,3,4-oxadiazolyl]-phenyl}-5-(2-ethylhexyloxy) -1,4-phenylenevinylene] (OxdEH-PPV) with electron-rich groups. The poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV), which is well known material for the polymer-based LED, was synthesized for the reference. We measured the current density vs. applied field (J-E) characteristics of the HTD and ETD with various thickness at different temperatures. The results of the J-E curves were analyzed by using the space charge limited conduction (SCLC) model. Based upon the SCLC model, μh and μe of MEH-PPV sample was measured to be ∼10-6cm2/Vs and ∼10-8cm2/Vs, respectively. For CzEH-PPV and OxdEH-PPV samples with electron-rich groups, μh was similar to μe with 10-10-10-11cm2/Vs. The μh and μe of CzEH-PPV and OxdEH-PPV samples was lower than that of MEH-PPV sample, but more balanced. The quantum efficiency of the LED by using CzEH-PPV or OxdEH-PPV materials was ∼10 times higher than that prepared from MEH-PPV. The balance of the μh and μe plays an important role for the quantum efficiency. We analyze the balance of the μh and μe and the relatively low mobilities of CzEH-PPV and OxdEH-PPV samples in terms of the heavier effective mass due to the asymmetric dipole distribution in the side chains. The results of photocurrent of the systems qualitatively agreed with the result of the electrical measurements. From AC impedance measurement of the LEDs, we observed that the relaxation time of MEH-PPV was shorter than that of OxdEH-PPV sample because of the higher mobility of MEH-PPV sample.",

keywords = "CzEH-PPV, Light-emitting diode, Mobility, OxdEH-PPV, Time of flight",

author = "Kang, {H. S.} and Kim, {K. H.} and Kim, {M. S.} and Park, {K. T.} and Kim, {K. M.} and Lee, {T. H.} and Lee, {C. Y.} and J. Joo and Lee, {D. W.} and Hong, {Y. R.} and K. Kim and Lee, {G. J.} and Jin, {J. I.}",

note = "Funding Information: This work was supported in part by the CRM-KOSEF (2001). ",

year = "2002",

month = oct,

day = "20",

doi = "10.1016/S0379-6779(02)00126-1",

language = "English",

volume = "130",

pages = "279--283",

journal = "Synthetic Metals",

issn = "0379-6779",

publisher = "Elsevier B.V.",

number = "3",

}

TY - JOUR

T1 - Electrical characteristics of light-emitting diode based on poly(p-phenylenevinylene) derivatives

T2 - CzEH-PPV and OxdEH-PPV

AU - Kang, H. S.

AU - Kim, K. H.

AU - Kim, M. S.

AU - Park, K. T.

AU - Kim, K. M.

AU - Lee, T. H.

AU - Lee, C. Y.

AU - Joo, J.

AU - Lee, D. W.

AU - Hong, Y. R.

AU - Kim, K.

AU - Lee, G. J.

AU - Jin, J. I.

N1 - Funding Information: This work was supported in part by the CRM-KOSEF (2001).

PY - 2002/10/20

Y1 - 2002/10/20

N2 - In the light-emitting devices (LEDs) based on the π-conjugated polymers, the relationship between the quantum efficiency and the balance of hole (μh) and electron (μe) mobility has been investigated. In order to measure the μh and μe of the LEDs based on π-conjugated polymers, we fabricated the hole transport device (HTD) and the electron transport device (ETD) by using various metal electrodes with different work functions. For the materials of light emitting layer, we synthesized poly[2-(N-carbazolyl)-5-(2-ethylhexyloxy)-1,4-phenylene vinylene] (CzEH-PPV) and poly[2-{4-[5-(4-tert-butylphenyl)-1,3,4-oxadiazolyl]-phenyl}-5-(2-ethylhexyloxy) -1,4-phenylenevinylene] (OxdEH-PPV) with electron-rich groups. The poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV), which is well known material for the polymer-based LED, was synthesized for the reference. We measured the current density vs. applied field (J-E) characteristics of the HTD and ETD with various thickness at different temperatures. The results of the J-E curves were analyzed by using the space charge limited conduction (SCLC) model. Based upon the SCLC model, μh and μe of MEH-PPV sample was measured to be ∼10-6cm2/Vs and ∼10-8cm2/Vs, respectively. For CzEH-PPV and OxdEH-PPV samples with electron-rich groups, μh was similar to μe with 10-10-10-11cm2/Vs. The μh and μe of CzEH-PPV and OxdEH-PPV samples was lower than that of MEH-PPV sample, but more balanced. The quantum efficiency of the LED by using CzEH-PPV or OxdEH-PPV materials was ∼10 times higher than that prepared from MEH-PPV. The balance of the μh and μe plays an important role for the quantum efficiency. We analyze the balance of the μh and μe and the relatively low mobilities of CzEH-PPV and OxdEH-PPV samples in terms of the heavier effective mass due to the asymmetric dipole distribution in the side chains. The results of photocurrent of the systems qualitatively agreed with the result of the electrical measurements. From AC impedance measurement of the LEDs, we observed that the relaxation time of MEH-PPV was shorter than that of OxdEH-PPV sample because of the higher mobility of MEH-PPV sample.

AB - In the light-emitting devices (LEDs) based on the π-conjugated polymers, the relationship between the quantum efficiency and the balance of hole (μh) and electron (μe) mobility has been investigated. In order to measure the μh and μe of the LEDs based on π-conjugated polymers, we fabricated the hole transport device (HTD) and the electron transport device (ETD) by using various metal electrodes with different work functions. For the materials of light emitting layer, we synthesized poly[2-(N-carbazolyl)-5-(2-ethylhexyloxy)-1,4-phenylene vinylene] (CzEH-PPV) and poly[2-{4-[5-(4-tert-butylphenyl)-1,3,4-oxadiazolyl]-phenyl}-5-(2-ethylhexyloxy) -1,4-phenylenevinylene] (OxdEH-PPV) with electron-rich groups. The poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV), which is well known material for the polymer-based LED, was synthesized for the reference. We measured the current density vs. applied field (J-E) characteristics of the HTD and ETD with various thickness at different temperatures. The results of the J-E curves were analyzed by using the space charge limited conduction (SCLC) model. Based upon the SCLC model, μh and μe of MEH-PPV sample was measured to be ∼10-6cm2/Vs and ∼10-8cm2/Vs, respectively. For CzEH-PPV and OxdEH-PPV samples with electron-rich groups, μh was similar to μe with 10-10-10-11cm2/Vs. The μh and μe of CzEH-PPV and OxdEH-PPV samples was lower than that of MEH-PPV sample, but more balanced. The quantum efficiency of the LED by using CzEH-PPV or OxdEH-PPV materials was ∼10 times higher than that prepared from MEH-PPV. The balance of the μh and μe plays an important role for the quantum efficiency. We analyze the balance of the μh and μe and the relatively low mobilities of CzEH-PPV and OxdEH-PPV samples in terms of the heavier effective mass due to the asymmetric dipole distribution in the side chains. The results of photocurrent of the systems qualitatively agreed with the result of the electrical measurements. From AC impedance measurement of the LEDs, we observed that the relaxation time of MEH-PPV was shorter than that of OxdEH-PPV sample because of the higher mobility of MEH-PPV sample.

KW - CzEH-PPV

KW - Light-emitting diode

KW - Mobility

KW - OxdEH-PPV

KW - Time of flight

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U2 - 10.1016/S0379-6779(02)00126-1

DO - 10.1016/S0379-6779(02)00126-1

M3 - Article

AN - SCOPUS:18544376087

SN - 0379-6779

VL - 130

SP - 279

EP - 283

JO - Synthetic Metals

JF - Synthetic Metals

IS - 3

ER -

Electrical characteristics of light-emitting diode based on poly(p-phenylenevinylene) derivatives: CzEH-PPV and OxdEH-PPV

Abstract

Bibliographical note

Keywords

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