Impedance spectroscopy on copper phthalocyanine diodes with surface-induced molecular orientation

Chang-Hyun Kim (1) , Htay Hlaing (2) , Shyuan Yang (2) , Yvan Bonnassieux (1) , Gilles Horowitz (1) , Ioannis Kymissis (2)

1 LPICM - Laboratoire de physique des interfaces et des couches minces [Palaiseau]
2 Department of Electrical Engineering

Molecular orientation and packing motif governs charge-transport property of organic semiconductor films, especially for planar small molecules. We analyze the surface-induced orientation of copper phthalocyannine (CuPc) molecules deposited on graphene or poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) covered indium-tin-oxide (PEDOT:PSS/ITO). The CuPc films deposited on graphene are templated with preferential face-on stacking, whereas the molecules on PEDOT:PSS/ITO crystallize with edge-on ordering. Static current-voltage measurement and small-signal impedance spectroscopy are combined to elucidate the structural impact on the electrical response when those films are part of a rectifying diode. The graphene-templated diode shows enhanced out-of-plane hole conduction as compared to the diode with a PEDOT:PSS/ITO contact. Equivalent circuits describing charge injection and transport properties are proposed.

Domaines: Electronique; Matériaux

Chang-Hyun Kim, Htay Hlaing, Shyuan Yang, Yvan Bonnassieux, Gilles Horowitz, et al.. Impedance spectroscopy on copper phthalocyanine diodes with surface-induced molecular orientation. Organic Electronics, 2014, 15 (8), pp.1724-1730. ⟨10.1016/j.orgel.2014.04.039⟩. ⟨hal-00997310⟩