Title

Vacuum level in an   infinite solid as a unified scheme for intrinsic band alignment

Reporter

Prof. Shengbai Zhang

Reporter’s   institution

Department of Physics,   Applied Physics and Astronomy, Rensselaer Polytechnic Institute, Troy, New   York, USA

Report time

2019-07-05 14:00

Report location

Conference room on the 9th floor（9004）of Hefei National   Laboratory for Physical Sciences at the Microscale

Organizer

Hefei National Laboratory for Physical   Sciences at the Microscale,Overseas Expertise   Introduction Center for Discipline Innovation, International Center for   Chemical Theory (ICCT), School of Chemistry and Materials Science

Report introduction

Abstract:

Based on the recent theory of built-in   potential [1], we develop a scheme for intrinsic band alignment where the   vacuum-level position in an infinite solid can be identified and used as the   common energy reference among dissimilar bulk materials [2]. Unique to this theory   is the recognition of an orientation dependence of bulk energies with respect   to the vacuum due to bulk quadrupole – a quantity that can now be   unambiguously evaluated. It reveals that the long-pursued concept of a   universal band alignment is ill-defined because of the orientation-dependent   quadrupole. This information lays solid ground for understanding intrinsic   band alignment with respect to vacuum, which is vitally important for   practical applications ranging from solid-state band offset, electrochemical   potential of a cell, to redox potential in electrochemistry. Work was in   collaboration with Choe and West and supported by US DOE under Grant No.   DE-SC0002623.

[1] D.-H. Choe, D.   West, and S. Zhang, Phys. Rev. Lett. 121, 196802 (2018).

[2] D.-H. Choe, D.   West, and S. Zhang, arXiv:1906.10162.

About the speaker:

Prof Shengbai Zhang received his Ph. D. in   Physics from the University of California at Berkeley in 1989 under the   supervision of Professor Marvin L. Cohen. Dr. Zhang then joined Xerox PARC in   Palo Alto California where he performed postdoctoral research with Dr. Jim   Chadi and Dr. John Northrup. In 1991 he moved to the National Renewable   Energy Laboratory (NREL) in Golden Colorado and became group leader for   Computational Materials Science in 2005. In 2008 he was appointed Senior   Kodosky Constellation Chair at Rensselaer Polytechnic Institute in Troy NY.   Prof. Zhang has a broad theoretical research background in computational   materials physics which covers a range of inorganic and organic   semiconductors and solids for bulk properties defect structures and surface   physics. His most recent work involves earth-abundant photovoltaic materials   phase change memory materials van der Waals interaction in organic   semiconductors lithium battery materials hydrogen storage topological   insulators graphene and excited state dynamics. Dr. Zhang has more than 309   peer-reviewed publications with more than 19000 citations (H index = 69). He   has been a Fellow of the American Physical Society since 2001.