Time-resolved soft X-ray photoelectron spectroscopy has been utilized to reveal a time evolution of excitation states of metal and metaloxo phthalocyanine (MPc; M = Cu and TiO) and fullerene (C 60 ) in the ultrathin layered MPc/C 60 /TiO 2 (110) systems. C 1s core-level photoemission peaks of MPc and C 60 were monitored to assess spontaneous changes induced by ultraviolet laser. The C 1s peaks of both species move toward higher binding energies, reflecting cationization of the molecules as a result of dissociation of photoexcited excitons followed by electron transfer from the molecules to TiO 2 . The magnitude of the C 60 C 1s peak shift is as large as 13-14 meV, whereas the shift of only 7 meV is induced when phthalocyanine-free C 60 /TiO 2 (110) is excited. Photoresponsivity of C 60 is enhanced when C 60 coexists with the phthalocyanine molecules. An efficient energy transfer from photoexcited MPc to C 60 and a resultant exciton formation in C 60 are responsible for this enhancement.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films