The interfacial electronic structure of a bilayer of fullerene (C60) and zinc phthalocyanine (ZnPc) grown on aluminum-doped zinc oxide (AZO) substrates has been evaluated by X-ray and ultraviolet photoemission spectroscopy. The energy difference between the highest occupied molecular orbital (HOMO) level of the ZnPc layer and the lowest unoccupied molecular orbital (LUMO) level of the C60 layer (EDHOMO − EALUMO) was determined and compared to that grown on an indium tin oxide (ITO) substrate. The EDHOMO − EALUMO value of the heterojunction on AZO was 1.4 eV, while that on ITO was 1.1 eV. This result is discussed in terms of the differences of the work function and resistivity of each transparent conductive oxide. We also obtained complete energy level diagrams of C60/ZnPc/AZO and C60/ZnPc/ITO.
Bibliographical noteFunding Information:
This work was supported by a research project of the National Research Foundation of Korea (Grant No. 2015R1D1A1A02061033 ), the Yonsei University Future-leading Research Initiative (Grant No. 2015-22-0083 ), and the Technology Innovation Program (Grant No. 10052274) funded by the Ministry of Trade, Industry & Energy (Korea).
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry