Correlation of Molecular Orientations at the Interface of Organic Double-Layered Thin Films

Abstract

Correlation of molecular orientations in the respective layers of vapor-deposited double-layered thin films of N,N′-dimethylperylene-3,4,9,10-bis(dicarboximide) (DM-PBDCI) and chloroaluminum phthalocyanine (ClAlPc) has been examined by means of X-ray diffraction and (polarized) electronic absorption. After examining molecular orientations in single-layered thin films, correlated orientations in double-layered films were disclosed as ClAlPc(1 1 0)/DM-PBDCI (0 1 1)/SS and ClAlPc(1 1 0)/DM-PBDCI(0 0 2)ISS for the films prepared at r.t. and hgh temperatures, respectively, and DM-PBDCI(1 0 2)/ClAlPc(0 4 0)/SS, where SS denotes a substrate. Further, it was derived by analyzing the results of electronic absorption spectra that transition dipole moments of two different molecules facing to each other at the interface of double-layered thin films are in most cases perpendicular or parallel to one another, and this could explain the observed correlations in molecular orientations above.