Morphology and structural properties of thin rubrene crystallites grown on graphite

TL;DR

This study explores the controlled growth, morphology, and stability of orthorhombic rubrene crystals on graphite, aiming to optimize their electronic properties for organic semiconductor applications.

Contribution

It demonstrates a method for growing stable orthorhombic rubrene crystals on graphite via controlled heating and deposition, advancing understanding of their structural and stability characteristics.

Findings

Successful growth of orthorhombic rubrene on graphite

Enhanced thermal stability of the crystals

Insights into photodegradation mechanisms

Abstract

Crystallization of rubrene, progressing from an amorphous phase to a triclinic meta-stable and ultimately to the orthorhombic stable phase, offers broad applications not only in organic electronic devices but also for in-depth studies of optical and electronic properties, including exciton distribution and dynamics. We investigate the crystallization of rubrene on highly oriented pyrolytic graphite (HOPG), aiming at the growth of the preferred rubrene orthorhombic phase, which has been reported to have one of the highest charge mobilities in organic semiconductors. This is achieved through controlled heating and enhanced partial pressure. Through precise control of the initial deposition on the substrate, we investigate the growth habit of rubrene crystals by high-rate heat treatment beyond the second crystallization temperature. Furthermore, this work addresses thermal stability and photodegradation across various morphologies.