The interfacial electronic structure of a bilayer of chloroaluminum phthalocyanine (ClAlPc) and pentacene grown on indium tin oxide (ITO) has been studied using synchrotron-radiation-excited photoelectron spectroscopy. The energy difference between the highest occupied molecular orbital (HOMO) level of the pentacene layer and the lowest unoccupied molecular orbital (LUMO) level of the ClAlPc layer (EHOMO D − ELUMO A) was determined and compared with that of C60/pentacene bilayers. The EHOMO D − ELUMO A of a heterojunction with ClAlPc was found to be 1.3 eV while that with C60 was 0.9 eV. This difference is discussed in terms of the difference in the ionization energy of each acceptor materials. We also obtained the complete energy level diagrams of both ClAlPc/pentacene/ITO and C60/pentacene/ITO.
Bibliographical noteFunding Information:
This work was supported in part by the National Science Foundation (NSF) under Grant No. CHE-0807368 and by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2013R1A1A4A01011392). The National Synchrotron Light Source (NSLS) is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886.
© 2014, The Korean Physical Society.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)