Structural Characterization of Mixed-Stack Charge Transfer Films of 2-Octadecyl-7,7,8,8-tetracyanoquinodimethane and 5,10-Dimethyl-5,10-dihydrophenazine Prepared by the Langmuir−Blodgett Technique and Donor Doping. 2. Morphology and Annealing Effects Investigated by Atomic Force Microscopy and Ultraviolet−Visible−Near-Infrared, and Infrared Spectroscopies

Abstract

Morphology and annealing effects of mixed-stack charge transfer (CT) complex films of 2-octadecyl-7,7,8,8-tetracyanoquinodimethane (octadecyl-TCNQ) doped by 5,10-dimethyl-5,10-dihydrophenazine ((Me)2P) have been investigated by atomic force microscopy (AFM) and ultraviolet−visible−near-infrared (UV−vis−NIR) and infrared (IR) spectroscopies. The AFM measurements scanned at room temperature show that the 11-layer CT film consists of layered platelet microcrystal domains with a layer distance of 3.3 nm, which is in good agreement with the distance obtained by an X-ray diffraction experiment. It is likely that each layer in the CT film has a bimolecular layer structure as in the case of Langmuir−Blodgett (LB) films of neutral octadecyl-TCNQ. A two-dimensionally resolved molecular arrangement of octadecyl-TCNQ and (Me)2P is observed inside the domains by a high-resolution AFM image. The inter- and intrastack periods, which are across and along the CT stacks, are 0.96 and 0.83 nm, respectively, with an intersec...