TY - JOUR
T1 - Valence-band electronic structure evolution of graphene oxide upon thermal annealing for optoelectronics
AU - Yamaguchi, Hisato
AU - Ogawa, Shuichi
AU - Watanabe, Daiki
AU - Hozumi, Hideaki
AU - Gao, Yongqian
AU - Eda, Goki
AU - Mattevi, Cecilia
AU - Fujita, Takeshi
AU - Yoshigoe, Akitaka
AU - Ishizuka, Shinji
AU - Adamska, Lyudmyla
AU - Yamada, Takatoshi
AU - Dattelbaum, Andrew M.
AU - Gupta, Gautam
AU - Doorn, Stephen K.
AU - Velizhanin, Kirill A.
AU - Teraoka, Yuden
AU - Chen, Mingwei
AU - Htoon, Han
AU - Chhowalla, Manish
AU - Mohite, Aditya D.
AU - Takakuwa, Yuji
N1 - Funding Information:
The authors acknowledge T. Kaga and S. Takabayashi of Tohoku University, Japan, and E. Cheng and D. Voiry of Rutgers University for the experimental support. The authors also acknowledge Asbury Carbon, NJ for generously supplying the starting graphite powders as a part of their U.S. national laboratory supporting program. H. Y. and M. C. acknowledge Donald H. Jacobs’ Chair funding from Rutgers University. H. Y. acknowledges the Laboratory Directed Research and Development (LDRD) Director's Postdoctoral Fellowship of LANL, and the Japanese Society for the Promotion of Science (JSPS) Postdoctoral Fellowship for Research Abroad for financial support. This work was performed under the Cooperative Research Program of the “Network Joint Research Center for Materials and Devices” by the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan. The XPS measurements using synchrotron radiation were performed at BL23SU in SPring-8 under the “Nano-net Project” of the Japan Synchrotron Research Institute (JASRI) and Japan Atomic Energy Agency (JAEA) (proposal Nos. 2010A3874, 2010B3879, and 2014B3874). The research was also supported by the LDRD Program and performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the US Department of Energy (DOE) Office of Science. Los Alamos National Laboratory, an affirmative action equal opportunity employer, is operated by Los Alamos National Security, LLC, for the National Nuclear Security Administration of the US Department of Energy under contract DE-AC52-06NA25396.
Publisher Copyright:
© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2016/9/1
Y1 - 2016/9/1
N2 - 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.
AB - 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.
KW - Fermi level
KW - graphene oxide
KW - optoelectronic
KW - ultraviolet photoelectron spectroscopy
KW - valence-band electronic structure
UR - http://www.scopus.com/inward/record.url?scp=84963660234&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84963660234&partnerID=8YFLogxK
U2 - 10.1002/pssa.201532855
DO - 10.1002/pssa.201532855
M3 - Article
AN - SCOPUS:84963660234
SN - 1862-6300
VL - 213
SP - 2380
EP - 2386
JO - Physica Status Solidi (A) Applications and Materials Science
JF - Physica Status Solidi (A) Applications and Materials Science
IS - 9
ER -