The energy level alignment between C 60 and Al has been investigated by using ultraviolet photoelectron spectroscopy. To obtain the interfacial electronic structure between C 60 and Al, C 60 was deposited on a clean Al substrate in a stepwise manner. The valence-band spectra were measured immediately after each step of C 60 deposition without breaking the vacuum. The measured onset of the highest occupied molecular orbital energy level was located at 1.59 eV from the Fermi level of Al. The vacuum level was shifted 0.68 eV toward lower binding energy with additional C 60 layers. The observed vacuum level shift means that the interface dipole exists at the interface between C 60 and Al. The barrier height of electron injection from Al to C 60 is 0.11 eV, which is smaller value than that of hole injection.
Bibliographical noteFunding Information:
This work was supported by Brain Korea 21 (BK21) project of Korea Research Foundation (KRF), and Korea Science and Engineering Foundation (KOSEF) through National Core Research Center for Nanomedical Technology.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Physics and Astronomy(all)
- Surfaces and Interfaces
- Surfaces, Coatings and Films