Orientation of silicon phthalocyanine thin films revealed using polarized X-ray absorption spectroscopy

Sekiguchi, Tetsuhiro  ; Baba, Yuji  ; Shimoyama, Iwao   ; Hirao, Norie; Honda, Mitsunori   ; Deng, J.*

The orientation of organic semiconducting molecules on surfaces plays a crucial role in improving the properties of electronic devices. We prepared thin films of silicon phthalocyanine dichroride (SiPcCl) on graphite spin-cast followed by heating to 350C at ambient condition. We investigate the molecular orientation of the films using angle-dependent near-edge X-ray absorption fine-structure (NEXAFS) spectroscopy. Si 1s NEXAFS spectra for the thin films after annealing are very different each other, indicating that the corresponding reactions thus the structures of final products are different. The structures of the reaction products are estimated with the help of ab initio molecular orbital calculations that fit the observed NEXAFS spectra.