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 oC. 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 oC 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.
@article{arxiv.1605.01048,
title = {Valence band electronic structure evolution of graphene oxide upon thermal annealing for optoelectronics},
author = {Hisato Yamaguchi and Shuichi Ogawa and Daiki Watanabe and Hideaki Hozumi and Yongqian Gao and Goki Eda and Cecilia Mattevi and Takeshi Fujita and Akitaka Yoshigoe and Shinji Ishizuka and Lyudmyla Adamska and Takatoshi Yamada and Andrew M. Dattelbaum and Gautam Gupta and Stephen K. Doorn and Kirill A. Velizhanin and Yuden Teraoka and Mingwei Chen and Han Htoon and Manish Chhowalla and Aditya D. Mohite and Yuji Takakuwa},
journal= {arXiv preprint arXiv:1605.01048},
year = {2016}
}
Comments
9 pages, 4 figures in physica status solidi (a) 2016