How Biphthalocyanine Molecules Do Arrange on Single Crystalline Surfaces

Phthalocyanine molecules have been the subject of a large number of investigations due to their versatile applications in the area of gas-sensing devices, photovoltaic

materials, light-emitting diodes, solar and fuel cells and molecular magnets. There is an evident need to characterize the molecular arrangement and the electronic properties of such organic molecules on the substrates, for getting a better understanding of the molecule-molecule as well as molecule-surface interactions.To achieve this goal, it is crucial to characterize the molecular arrangement of the molecules and link their physical properties to the structure of the film. In this study, we focus on the double decker biphthalocyanine of lutetium (LuPc2), which interest relies in its particular electronic properties. We have studied the growth and structure of LuPc2 molecules on clean and passivated Si(100)-2x1 and also on Au(111) surface, by molecular vapor deposition under vacuum [1, 2, 3].

We have used various surface experimental techniques such as surface differential optical spectroscopies, local probe microscopies and electron spectroscopies. We identified the growth mode and found that on the passivated silicon surface favors the self-organization of the molecules and we evidenced a strong influence of the flux during the formation of the molecular films. We could then propose the scenario for the growth of LuPc2 molecules on the two silicon surfaces, clean and passivated ones from few molecules up to about 40 nm.

On  Au(111) surface, molecules are found to absorb flat on the surface forming a bilayer [5] at initial coverages whereas clusters develop for larger coverages influencing their electronic structure.

References                                                                                                                                                              

1.   I. Bidermane et al., J. Chem. Phys. 138, 234701 (2013)

2.   S. Boudet et al., Phys. Rev. B 86, 115413 (2012)

3.  S. Boudet et al.,submitted to J. Phys. Chem. C

4.  Z. H. Cheng et al., J. Phys. Chem. C, 111,  2007

5.  I. Bidermane et al, in manuscript