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

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

^*Corresponding author for this work

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

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 (V_fbs) 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) V_fb 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 V_fb high; they also imply that a high V_fb, dissociates optically excited electrons and holes to make colors center resulting in photochromism at a high efficiency.

Original language	English
Pages (from-to)	5361-5366
Number of pages	6
Journal	Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
Volume	35
Issue number	10
Publication status	Published - 1996
Externally published	Yes

Keywords

Electrochromism
Flat band potential
Photochromism
Tungsten oxide
Urbach's tail

ASJC Scopus subject areas

Physics and Astronomy (miscellaneous)
Engineering(all)

Cite this

Band edge disorder producing Urbach's tail and enhanced photochromic efficiency caused by density of states inside band gap in tungsten oxide films. / Kubo, Takaya; Nishikitani, Yoshinori; Kuroda, Nobuyuki et al.

In: Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers, Vol. 35, No. 10, 1996, p. 5361-5366.

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

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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",

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journal = "Japanese Journal of Applied Physics, Part 1: Regular Papers & Short Notes",

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publisher = "Japan Society of Applied Physics",

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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

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

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

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ER -

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

Abstract

Keywords

ASJC Scopus subject areas

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