Oriented growth of pentacene films on vacuum-deposited polytetrafluoroethylene layers aligned by rubbing technique

TL;DR

This study explores how vacuum-deposited PTFE layers, aligned by rubbing, can direct the oriented growth of pentacene films, with the structure and morphology influenced by deposition parameters and layer thickness.

Contribution

It demonstrates the ability to control pentacene film orientation using vacuum-deposited PTFE layers aligned by rubbing, highlighting the effects of deposition conditions and layer thickness.

Findings

PTFE layers' structure depends on deposition parameters.

Rubbing technique creates unidirectional grooves for orientation.

Pentacene orientation improves with PTFE layer thickness and growth temperature.

Abstract

We investigated structure and morphology of PTFE layers deposited by vacuum process in dependence on deposition parameters: deposition rate, deposition temperature, electron activation energy and activation current. Pentacene (PnC) layers deposited on top of those PTFE films are used as a tool to demonstrate the orienting ability of the PTFE layers. The molecular structure of the PTFE films was investigated by use of infrared spectroscopy. By means of ellipsometry, values of refractive index between 1.33 and 1.36 have been obtained for PTFE films in dependence on deposition conditions. Using the cold friction technique orienting PTFE layers with unidirectional grooves are obtained. On top of these PTFE films oriented PnC layers were grown. The obtained order depends both on the PTFE layer thickness and on PnC growth temperature.