Electronic structures at the interfaces between copper phthalocyanine and layered materials

Copper phtalocyanine (CuPc) films with the thickness controlled in molecular scales have been grown epitaxially on (0001) surfaces of layered materials, and electronic interaction at the interfaces have been studied by photoelectron spectroscopy. Materials with different electronic properties having different work functions ${\mathrm{(E}}_{\mathrm{vac}})$ were chosen as the substrates; semiconducting ${\mathrm{MoTe}}_{\mathrm{2}}$ ${\mathrm{(E}}_{\mathrm{vac}}\mathrm{=4.0\hspace{0.17em}eV}\mathrm{),}$ semi-metallic highly oriented pyrolytic graphite ${\mathrm{(E}}_{\mathrm{vac}}\mathrm{=4.5\hspace{0.17em}eV})$ and metallic ${\mathrm{TaSe}}_{\mathrm{2}}$ ${\mathrm{(E}}_{\mathrm{vac}}\mathrm{=5.5\hspace{0.17em}eV}\mathrm{).}$ Formation of interface dipole layers was found at ${\mathrm{CuPc/TaSe}}_{\mathrm{2}}$ interfaces and molecular orbitals involved were identified.