Observation of spontaneous orientation polarization in evaporated films of organic light-emitting diode materials

Kohei Osada, Kenichi Goshi, Hironori Kaji, Chihaya Adachi, Hisao Ishii, Yutaka Noguchi

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

The molecular orientation in organic semiconductor films determines device performances. In particular, the spontaneous orientation of a permanent dipole moment (PDM) along the surface normal direction induces a polarization charge at the hetero-interfaces of stacked multilayer devices, and the interface charge dominates the charge accumulation and injection properties. Spontaneous orientation polarization (SOP) has been observed in the “randomly oriented” films of several organic semiconductor materials, and is potentially inherent in many common materials. Herein, we report that 11 additional molecules of organic light-emitting diode materials, including thermally activated delayed fluorescence emitters, and horizontally oriented emitters and electron transporters, exhibit SOP in their evaporated films. The experimental results clearly indicate that SOP frequently occurs in “horizontally oriented” films as well as “randomly oriented” films. The factors contributing to SOP formation are discussed in terms of the figure of merit per PDM. We found that strong intermolecular interactions tend to reduce the figure of merit. Moreover, we suggest the impact of SOP on device performances.

Original languageEnglish
Pages (from-to)313-317
Number of pages5
JournalOrganic Electronics
Volume58
DOIs
Publication statusPublished - Jul 1 2018

Fingerprint

Organic light emitting diodes (OLED)
light emitting diodes
Polarization
polarization
Semiconducting organic compounds
Dipole moment
organic semiconductors
figure of merit
emitters
dipole moments
Molecular orientation
transporter
Multilayers
Fluorescence
Semiconductor materials
Molecules
injection
Electrons
fluorescence
molecules

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Chemistry(all)
  • Condensed Matter Physics
  • Materials Chemistry
  • Electrical and Electronic Engineering

Cite this

Observation of spontaneous orientation polarization in evaporated films of organic light-emitting diode materials. / Osada, Kohei; Goshi, Kenichi; Kaji, Hironori; Adachi, Chihaya; Ishii, Hisao; Noguchi, Yutaka.

In: Organic Electronics, Vol. 58, 01.07.2018, p. 313-317.

Research output: Contribution to journalArticle

@article{6701a1b422a849a598c9546ae5916883,
title = "Observation of spontaneous orientation polarization in evaporated films of organic light-emitting diode materials",
abstract = "The molecular orientation in organic semiconductor films determines device performances. In particular, the spontaneous orientation of a permanent dipole moment (PDM) along the surface normal direction induces a polarization charge at the hetero-interfaces of stacked multilayer devices, and the interface charge dominates the charge accumulation and injection properties. Spontaneous orientation polarization (SOP) has been observed in the “randomly oriented” films of several organic semiconductor materials, and is potentially inherent in many common materials. Herein, we report that 11 additional molecules of organic light-emitting diode materials, including thermally activated delayed fluorescence emitters, and horizontally oriented emitters and electron transporters, exhibit SOP in their evaporated films. The experimental results clearly indicate that SOP frequently occurs in “horizontally oriented” films as well as “randomly oriented” films. The factors contributing to SOP formation are discussed in terms of the figure of merit per PDM. We found that strong intermolecular interactions tend to reduce the figure of merit. Moreover, we suggest the impact of SOP on device performances.",
author = "Kohei Osada and Kenichi Goshi and Hironori Kaji and Chihaya Adachi and Hisao Ishii and Yutaka Noguchi",
year = "2018",
month = "7",
day = "1",
doi = "10.1016/j.orgel.2018.04.026",
language = "English",
volume = "58",
pages = "313--317",
journal = "Organic Electronics: physics, materials, applications",
issn = "1566-1199",
publisher = "Elsevier",

}

TY - JOUR

T1 - Observation of spontaneous orientation polarization in evaporated films of organic light-emitting diode materials

AU - Osada, Kohei

AU - Goshi, Kenichi

AU - Kaji, Hironori

AU - Adachi, Chihaya

AU - Ishii, Hisao

AU - Noguchi, Yutaka

PY - 2018/7/1

Y1 - 2018/7/1

N2 - The molecular orientation in organic semiconductor films determines device performances. In particular, the spontaneous orientation of a permanent dipole moment (PDM) along the surface normal direction induces a polarization charge at the hetero-interfaces of stacked multilayer devices, and the interface charge dominates the charge accumulation and injection properties. Spontaneous orientation polarization (SOP) has been observed in the “randomly oriented” films of several organic semiconductor materials, and is potentially inherent in many common materials. Herein, we report that 11 additional molecules of organic light-emitting diode materials, including thermally activated delayed fluorescence emitters, and horizontally oriented emitters and electron transporters, exhibit SOP in their evaporated films. The experimental results clearly indicate that SOP frequently occurs in “horizontally oriented” films as well as “randomly oriented” films. The factors contributing to SOP formation are discussed in terms of the figure of merit per PDM. We found that strong intermolecular interactions tend to reduce the figure of merit. Moreover, we suggest the impact of SOP on device performances.

AB - The molecular orientation in organic semiconductor films determines device performances. In particular, the spontaneous orientation of a permanent dipole moment (PDM) along the surface normal direction induces a polarization charge at the hetero-interfaces of stacked multilayer devices, and the interface charge dominates the charge accumulation and injection properties. Spontaneous orientation polarization (SOP) has been observed in the “randomly oriented” films of several organic semiconductor materials, and is potentially inherent in many common materials. Herein, we report that 11 additional molecules of organic light-emitting diode materials, including thermally activated delayed fluorescence emitters, and horizontally oriented emitters and electron transporters, exhibit SOP in their evaporated films. The experimental results clearly indicate that SOP frequently occurs in “horizontally oriented” films as well as “randomly oriented” films. The factors contributing to SOP formation are discussed in terms of the figure of merit per PDM. We found that strong intermolecular interactions tend to reduce the figure of merit. Moreover, we suggest the impact of SOP on device performances.

UR - http://www.scopus.com/inward/record.url?scp=85046478038&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85046478038&partnerID=8YFLogxK

U2 - 10.1016/j.orgel.2018.04.026

DO - 10.1016/j.orgel.2018.04.026

M3 - Article

VL - 58

SP - 313

EP - 317

JO - Organic Electronics: physics, materials, applications

JF - Organic Electronics: physics, materials, applications

SN - 1566-1199

ER -