Soft X-Ray Emission and Absorption study of the Electronic Structure of the Organic Semiconductor Titanyl Phthalocyanine (TiO-Pc)

The electronic structure of thin films of the organic semiconductor titanyl phthalocyanine (TiO-Pc) has been investigated using synchrotron radiation-excited x-ray emission and absorption spectroscopies. The films were grown \textit{in-situ}, using organic molecular beam deposition. The C and N $K$-edge spectra display similarities with those from other metal-Pcs, while the O $K$-edge and Ti $L$-edge spectra support the premise that the titanyl species are spatially isolated. Good agreement is found between a calculation of the partial density of states and the measured spectra. The Ti $L$-edge spectra display marked differences with previous reports. Two energy-loss features are reported from resonant x-ray inelastic scattering of the Ti L-edge associated with Ti $3d$*-O $2p $and Ti $3d*$-N $2p$ charge transfer transitions. Our measurements will be discussed in the context of earlier soft x-ray studies of TiO-Pc, with particular attention paid to issues of contamination and beam damage.