Band gap, excitons, and Coulomb interaction in solid C60

作者：R.W. Lof, M. A. van Veenendaal, B. Koopmans, Harry T. Jonkman, G. A. Sawatzky · 发表于：Physical Review Letters · 年份：1992 · DOI：10.1103/physrevlett.68.3924 · 被引用次数：760 · 研究领域：Fullerene Chemistry and Applications、Graphene research and applications、Diamond and Carbon-based Materials Research

The band gap of solid ${\mathrm{C}}_{60}$ is found to be 2.3\ifmmode\pm\else\textpm\fi{}0.1 eV. The on-site molecular ${\mathrm{C}}_{60}$ Coulomb interaction (U) as determined from the KVV ${\mathrm{C}}_{60}$ Auger spectrum is found to be 1.6\ifmmode\pm\else\textpm\fi{}0.2 eV. This value of U is shown to lead to Frenkel-type molecular excitons in the 1.5--2 eV range. These results lead us to suggest that doped ${\mathrm{C}}_{60}$ should be considered as a highly correlated system with U/W comparable to that in high-${\mathit{T}}_{\mathit{c}}$ cuprates and that stoichiometric ${\mathrm{K}}_{3}$${\mathrm{C}}_{60}$ is a Mott-Hubbard insulator with a gap of about 0.7 eV.