Valence-band electronic structure evolution of graphene oxide upon thermal annealing for optoelectronics

Hisato Yamaguchi, Shuichi Ogawa, Daiki Watanabe, Hideaki Hozumi, Yongqian Gao, Goki Eda, Cecilia Mattevi, Takeshi Fujita, Akitaka Yoshigoe, Shinji Ishizuka, Lyudmyla Adamska, Takatoshi Yamada, Andrew M. Dattelbaum, Gautam Gupta, Stephen K. Doorn, Kirill A. Velizhanin, Yuden Teraoka, Mingwei Chen, Han Htoon, Manish ChhowallaAditya D. Mohite, Yuji Takakuwa

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


We report valence-band electronic structure evolution of graphene oxide (GO) upon its thermal reduction. The degree of oxygen functionalization was controlled by annealing temperature, and an electronic structure evolution was monitored using real-time ultraviolet photoelectron spectroscopy. We observed a drastic increase in the density of states around the Fermi level upon thermal annealing at ∼600 °C. The result indicates that while there is an apparent bandgap for GO prior to a thermal reduction, the gap closes after an annealing around that temperature. This trend of bandgap closure was correlated with the electrical, chemical, and structural properties to determine a set of GO material properties that is optimal for optoelectronics. The results revealed that annealing at a temperature of ∼500 °C leads to the desired properties, demonstrated by a uniform and an order of magnitude enhanced photocurrent map of an individual GO sheet compared to an as-synthesized counterpart.

Original languageEnglish
Pages (from-to)2380-2386
Number of pages7
JournalPhysica Status Solidi (A) Applications and Materials Science
Issue number9
Publication statusPublished - 2016 Sept 1


  • Fermi level
  • graphene oxide
  • optoelectronic
  • ultraviolet photoelectron spectroscopy
  • valence-band electronic structure

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Electrical and Electronic Engineering
  • Materials Chemistry


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