Electrical and Optical Properties of Porphyrin Single Crystals

Abstract

In this work, we investigate the transport and optical properties of single crystal 5,10,15,20-tetrakis (4-N-ethylpyridyl) porphyrin salts, [H2TEPyP4+·4I−]. The electrical conductivity exhibits high anisotropy, in that the conductivity along the stacking column, which is equal to 3.2 × 10−8Ω−1· cm−1, is three orders of magnitude larger than that perpendicular to the stacking column. The absorption spectra of the single crystals exhibit a blue shift in the B-band and significant red shifts in the Q-bands in comparison to the solution spectra. Polarized reflectance measurements of the crystals reveal that the anisotropic reflectance is most intense when the light polarization is parallel to the molecular plane. The complex dielectric function, plasma frequency, and optical conductivity associated with each electronic transition are calculated based on analysis with a dielectric-function model.