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

We report valence band electronic structure evolution of graphene oxide (GO) upon its thermal reduction. Degree of oxygen functionalization was controlled by annealing temperatures, and an electronic structure evolution was monitored using real-time ultraviolet photoelectron spectroscopy. We observed a drastic increase in density of states around the Fermi level upon thermal annealing at ~600 °C. The result indicates that while there is an apparent band gap for GO prior to a thermal reduction, the gap closes after an annealing around that temperature. This trend of band gap closure was correlated with 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 as-synthesized counterpart.
Authors:
 [1] ;  [2] ;  [2] ;  [2] ;  [1] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [1] ;  [8] ;  [1] ;  [1] ;  [1] ;  [1] ;  [6] ;  [5] ;  [1] ;  [9] more »;  [1] ;  [2] « less
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Tohoku Univ., Sendai (Japan). Inst. of Multidisciplinary Research for Advanced Materials (IMRAM)
  3. National Univ. of Singapore (Singapore)
  4. Imperial College, London (United Kingdom)
  5. Tohoku Univ., Sendai (Japan). WPI-Advanced Inst. for Materials Research
  6. Japan Atomic Energy Agency (JAEA), Kouto (Japan)
  7. Akita National College of Technology, Akita (Japan)
  8. National Inst. of Advanced Industrial Science and Technology (AIST), Tsukuba (Japan). Nanotube Research Center
  9. Rutgers Univ., Piscataway, NJ (United States)
Publication Date:
OSTI Identifier:
1254851
Report Number(s):
LA-UR--15-23672
Journal ID: ISSN 1862-6300
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Physica Status Solidi. A, Applications and Materials Science
Additional Journal Information:
Journal Name: Physica Status Solidi. A, Applications and Materials Science; Journal ID: ISSN 1862-6300
Publisher:
Wiley
Research Org:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE graphene oxide; valence band electronic structure; ultraviolet photoelectron spectroscopy; Fermi level; optoelectronic