Band edge disorder producing Urbach's tail and enhanced photochromic efficiency caused by density of states inside band gap in tungsten oxide films

Takaya Kubo, Yoshinori Nishikitani, Nobuyuki Kuroda, Mitsuo Matsuno

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

The band gap of WO3 and its disorder at the band edge were evaluated, assuming Urbach's rule, and flat-band potentials (Vfbs) were also measured on WO3 films with high photochromic efficiency (HPE) and low photochromic efficiency (LPE). The main results are as follows: 1) the optical absorption of LPE-WO3 sets on at higher photon energy than that of HPE-WO3, 2) HPE-WO3 has the density of states deeper in the band gap than LPE-WO3 does, and 3) Vfb of HPE-WO3 is higher than that of HPE-WO3. These results indicate that the band edge disorder of WO3, which is closely related to Urbach's tail, determines the Fermi level position, and therefore makes Vfb high; they also imply that a high Vfb, dissociates optically excited electrons and holes to make colors center resulting in photochromism at a high efficiency.

Original languageEnglish
Pages (from-to)5361-5366
Number of pages6
JournalJapanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
Volume35
Issue number10
Publication statusPublished - 1996
Externally publishedYes

Fingerprint

tungsten oxides
Oxide films
Tungsten
oxide films
Energy gap
disorders
Photochromism
photochromism
Color centers
color centers
Fermi level
Light absorption
optical absorption
Photons
Electrons
photons

Keywords

  • Electrochromism
  • Flat band potential
  • Photochromism
  • Tungsten oxide
  • Urbach's tail

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)
  • Engineering(all)

Cite this

@article{a5b8e4e61a1f4183bbf6454d226d0645,
title = "Band edge disorder producing Urbach's tail and enhanced photochromic efficiency caused by density of states inside band gap in tungsten oxide films",
abstract = "The band gap of WO3 and its disorder at the band edge were evaluated, assuming Urbach's rule, and flat-band potentials (Vfbs) were also measured on WO3 films with high photochromic efficiency (HPE) and low photochromic efficiency (LPE). The main results are as follows: 1) the optical absorption of LPE-WO3 sets on at higher photon energy than that of HPE-WO3, 2) HPE-WO3 has the density of states deeper in the band gap than LPE-WO3 does, and 3) Vfb of HPE-WO3 is higher than that of HPE-WO3. These results indicate that the band edge disorder of WO3, which is closely related to Urbach's tail, determines the Fermi level position, and therefore makes Vfb high; they also imply that a high Vfb, dissociates optically excited electrons and holes to make colors center resulting in photochromism at a high efficiency.",
keywords = "Electrochromism, Flat band potential, Photochromism, Tungsten oxide, Urbach's tail",
author = "Takaya Kubo and Yoshinori Nishikitani and Nobuyuki Kuroda and Mitsuo Matsuno",
year = "1996",
language = "English",
volume = "35",
pages = "5361--5366",
journal = "Japanese Journal of Applied Physics, Part 1: Regular Papers & Short Notes",
issn = "0021-4922",
publisher = "Japan Society of Applied Physics",
number = "10",

}

TY - JOUR

T1 - Band edge disorder producing Urbach's tail and enhanced photochromic efficiency caused by density of states inside band gap in tungsten oxide films

AU - Kubo, Takaya

AU - Nishikitani, Yoshinori

AU - Kuroda, Nobuyuki

AU - Matsuno, Mitsuo

PY - 1996

Y1 - 1996

N2 - The band gap of WO3 and its disorder at the band edge were evaluated, assuming Urbach's rule, and flat-band potentials (Vfbs) were also measured on WO3 films with high photochromic efficiency (HPE) and low photochromic efficiency (LPE). The main results are as follows: 1) the optical absorption of LPE-WO3 sets on at higher photon energy than that of HPE-WO3, 2) HPE-WO3 has the density of states deeper in the band gap than LPE-WO3 does, and 3) Vfb of HPE-WO3 is higher than that of HPE-WO3. These results indicate that the band edge disorder of WO3, which is closely related to Urbach's tail, determines the Fermi level position, and therefore makes Vfb high; they also imply that a high Vfb, dissociates optically excited electrons and holes to make colors center resulting in photochromism at a high efficiency.

AB - The band gap of WO3 and its disorder at the band edge were evaluated, assuming Urbach's rule, and flat-band potentials (Vfbs) were also measured on WO3 films with high photochromic efficiency (HPE) and low photochromic efficiency (LPE). The main results are as follows: 1) the optical absorption of LPE-WO3 sets on at higher photon energy than that of HPE-WO3, 2) HPE-WO3 has the density of states deeper in the band gap than LPE-WO3 does, and 3) Vfb of HPE-WO3 is higher than that of HPE-WO3. These results indicate that the band edge disorder of WO3, which is closely related to Urbach's tail, determines the Fermi level position, and therefore makes Vfb high; they also imply that a high Vfb, dissociates optically excited electrons and holes to make colors center resulting in photochromism at a high efficiency.

KW - Electrochromism

KW - Flat band potential

KW - Photochromism

KW - Tungsten oxide

KW - Urbach's tail

UR - http://www.scopus.com/inward/record.url?scp=0030259205&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0030259205&partnerID=8YFLogxK

M3 - Article

VL - 35

SP - 5361

EP - 5366

JO - Japanese Journal of Applied Physics, Part 1: Regular Papers & Short Notes

JF - Japanese Journal of Applied Physics, Part 1: Regular Papers & Short Notes

SN - 0021-4922

IS - 10

ER -