Chapter 4 Electrical conductance of directly linked porphyrin arrays

Abstract

This chapter discusses the electrical conductance of directly linked porphyrin arrays. The regularly arranged porphyrin arrays with ample electronic interactions can be promising in the applications, such as molecular wires, sensors, and optical nonlinear materials. For the application of molecular photonic and electronic wires, the overall length of the porphyrin arrays should be long enough for linkage of a nanoelectrode as a molecular electronic wire. To explore the electrical transport properties of individual porphyrin molecules for the application as molecular-scale devices, the electrical transport measurements of two extreme types of porphyrin arrays are performed. Directly linked linear orthogonal (Zn) and fused (Tn) porphyrin arrays for the possible applications as molecular photonic and electric wire are prepared. All electrical transport measurements are performed in vacuum to eliminate the effect of water on the conductance. Zn is promising as a photonic wire because of the exceptionally strong excitonic interactions between the neighboring porphyrin moieties arising from a close proximity with a reasonably long length. On the other hand, Tn has proven to be a good optical nonlinear material induced by extensive π-electron delocalization throughout the entire Tn arrays.