Optical, morphological, structural, electrical, molecular orientation, and electroluminescence characteristics of organic semiconductor films prepared at various deposition rates

Toshinori Matsushima, Koutaro Shiomura, Shigeki Naka, Hideyuki Murata

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Extremely high deposition rates of ≈ 7200 nm s - 1 for N,N′-diphenyl-N,N′-bis(1-naphthyl)-1,1′-biphenyl-4, 4′-diamine (α-NPD) and of ≈ 1700 nm s - 1 for tris(8-hydroxyquinoline)aluminum (Alq 3) are found to be possible by controlling source-substrate distances and crucible temperatures. Shapes of ultraviolet-visible absorption spectra and photoluminescence (PL) spectra, atomic force microscope images, X-ray diffraction patterns, PL quantum yields, PL lifetimes, and PL radiative decay rates of the films remain independent of the deposition rates ranging from 0.01 to 1000 nm s - 1. On the other hand, hole currents of hole-only α-NPD devices increase ≈ 3 times while electron currents of electron-only Alq 3 devices decrease by ≈ 1/60 as the deposition rates are increased from 0.01 to 10 nm s - 1. The increase in hole current is confirmed to arise from an increase in hole mobility of α-NPD measured using a time-of-flight technique. The increase in hole mobility is probably due to a parallel orientation of an electronic transition moment of α-NPD at the higher deposition rates. Moreover, the three orders of magnitude increase in deposition rate from 0.01 to 10 nm s - 1 of α-NPD and Alq 3 results in a relatively small increase in voltage of ≈ 15% and a decrease in external quantum efficiency of ≈ 30% in organic light-emitting diodes (OLEDs). The reduction of the OLED performance is attributable to the marked decrease in electron current relative to the slight increase in hole current, indicating a decrease in charge balance factor at the higher deposition rates.

Original languageEnglish
Pages (from-to)2283-2288
Number of pages6
JournalThin Solid Films
Volume520
Issue number6
DOIs
Publication statusPublished - Jan 1 2012
Externally publishedYes

Fingerprint

Semiconducting organic compounds
Molecular orientation
Electroluminescence
organic semiconductors
Deposition rates
electroluminescence
Photoluminescence
photoluminescence
Hole mobility
hole mobility
Organic light emitting diodes (OLED)
Electrons
light emitting diodes
atomic spectra
electrons
Diamines
Crucibles
Quantum yield
crucibles
diamines

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry

Cite this

Optical, morphological, structural, electrical, molecular orientation, and electroluminescence characteristics of organic semiconductor films prepared at various deposition rates. / Matsushima, Toshinori; Shiomura, Koutaro; Naka, Shigeki; Murata, Hideyuki.

In: Thin Solid Films, Vol. 520, No. 6, 01.01.2012, p. 2283-2288.

Research output: Contribution to journalArticle

@article{7e32eaec460e4af7b5bb35fb42f770f4,
title = "Optical, morphological, structural, electrical, molecular orientation, and electroluminescence characteristics of organic semiconductor films prepared at various deposition rates",
abstract = "Extremely high deposition rates of ≈ 7200 nm s - 1 for N,N′-diphenyl-N,N′-bis(1-naphthyl)-1,1′-biphenyl-4, 4′-diamine (α-NPD) and of ≈ 1700 nm s - 1 for tris(8-hydroxyquinoline)aluminum (Alq 3) are found to be possible by controlling source-substrate distances and crucible temperatures. Shapes of ultraviolet-visible absorption spectra and photoluminescence (PL) spectra, atomic force microscope images, X-ray diffraction patterns, PL quantum yields, PL lifetimes, and PL radiative decay rates of the films remain independent of the deposition rates ranging from 0.01 to 1000 nm s - 1. On the other hand, hole currents of hole-only α-NPD devices increase ≈ 3 times while electron currents of electron-only Alq 3 devices decrease by ≈ 1/60 as the deposition rates are increased from 0.01 to 10 nm s - 1. The increase in hole current is confirmed to arise from an increase in hole mobility of α-NPD measured using a time-of-flight technique. The increase in hole mobility is probably due to a parallel orientation of an electronic transition moment of α-NPD at the higher deposition rates. Moreover, the three orders of magnitude increase in deposition rate from 0.01 to 10 nm s - 1 of α-NPD and Alq 3 results in a relatively small increase in voltage of ≈ 15{\%} and a decrease in external quantum efficiency of ≈ 30{\%} in organic light-emitting diodes (OLEDs). The reduction of the OLED performance is attributable to the marked decrease in electron current relative to the slight increase in hole current, indicating a decrease in charge balance factor at the higher deposition rates.",
author = "Toshinori Matsushima and Koutaro Shiomura and Shigeki Naka and Hideyuki Murata",
year = "2012",
month = "1",
day = "1",
doi = "10.1016/j.tsf.2011.09.060",
language = "English",
volume = "520",
pages = "2283--2288",
journal = "Thin Solid Films",
issn = "0040-6090",
publisher = "Elsevier",
number = "6",

}

TY - JOUR

T1 - Optical, morphological, structural, electrical, molecular orientation, and electroluminescence characteristics of organic semiconductor films prepared at various deposition rates

AU - Matsushima, Toshinori

AU - Shiomura, Koutaro

AU - Naka, Shigeki

AU - Murata, Hideyuki

PY - 2012/1/1

Y1 - 2012/1/1

N2 - Extremely high deposition rates of ≈ 7200 nm s - 1 for N,N′-diphenyl-N,N′-bis(1-naphthyl)-1,1′-biphenyl-4, 4′-diamine (α-NPD) and of ≈ 1700 nm s - 1 for tris(8-hydroxyquinoline)aluminum (Alq 3) are found to be possible by controlling source-substrate distances and crucible temperatures. Shapes of ultraviolet-visible absorption spectra and photoluminescence (PL) spectra, atomic force microscope images, X-ray diffraction patterns, PL quantum yields, PL lifetimes, and PL radiative decay rates of the films remain independent of the deposition rates ranging from 0.01 to 1000 nm s - 1. On the other hand, hole currents of hole-only α-NPD devices increase ≈ 3 times while electron currents of electron-only Alq 3 devices decrease by ≈ 1/60 as the deposition rates are increased from 0.01 to 10 nm s - 1. The increase in hole current is confirmed to arise from an increase in hole mobility of α-NPD measured using a time-of-flight technique. The increase in hole mobility is probably due to a parallel orientation of an electronic transition moment of α-NPD at the higher deposition rates. Moreover, the three orders of magnitude increase in deposition rate from 0.01 to 10 nm s - 1 of α-NPD and Alq 3 results in a relatively small increase in voltage of ≈ 15% and a decrease in external quantum efficiency of ≈ 30% in organic light-emitting diodes (OLEDs). The reduction of the OLED performance is attributable to the marked decrease in electron current relative to the slight increase in hole current, indicating a decrease in charge balance factor at the higher deposition rates.

AB - Extremely high deposition rates of ≈ 7200 nm s - 1 for N,N′-diphenyl-N,N′-bis(1-naphthyl)-1,1′-biphenyl-4, 4′-diamine (α-NPD) and of ≈ 1700 nm s - 1 for tris(8-hydroxyquinoline)aluminum (Alq 3) are found to be possible by controlling source-substrate distances and crucible temperatures. Shapes of ultraviolet-visible absorption spectra and photoluminescence (PL) spectra, atomic force microscope images, X-ray diffraction patterns, PL quantum yields, PL lifetimes, and PL radiative decay rates of the films remain independent of the deposition rates ranging from 0.01 to 1000 nm s - 1. On the other hand, hole currents of hole-only α-NPD devices increase ≈ 3 times while electron currents of electron-only Alq 3 devices decrease by ≈ 1/60 as the deposition rates are increased from 0.01 to 10 nm s - 1. The increase in hole current is confirmed to arise from an increase in hole mobility of α-NPD measured using a time-of-flight technique. The increase in hole mobility is probably due to a parallel orientation of an electronic transition moment of α-NPD at the higher deposition rates. Moreover, the three orders of magnitude increase in deposition rate from 0.01 to 10 nm s - 1 of α-NPD and Alq 3 results in a relatively small increase in voltage of ≈ 15% and a decrease in external quantum efficiency of ≈ 30% in organic light-emitting diodes (OLEDs). The reduction of the OLED performance is attributable to the marked decrease in electron current relative to the slight increase in hole current, indicating a decrease in charge balance factor at the higher deposition rates.

UR - http://www.scopus.com/inward/record.url?scp=84855964211&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84855964211&partnerID=8YFLogxK

U2 - 10.1016/j.tsf.2011.09.060

DO - 10.1016/j.tsf.2011.09.060

M3 - Article

AN - SCOPUS:84855964211

VL - 520

SP - 2283

EP - 2288

JO - Thin Solid Films

JF - Thin Solid Films

SN - 0040-6090

IS - 6

ER -