Preparation and investigation of the formation mechanism of organic single crystal nanostructures of PTCDA

Abstract

Different types of nanostructures of an organic dye compound, perylene-3,4,9,10-tetracarboxylic-dianhydride (PTCDA), are prepared on anodic alumina oxide (AAO) at different values of substrate temperature (Ts) by a facile physical vapor deposition (PVD) method in a molecular beam epitaxy (MBE) system. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) techniques are applied to the systematical characterization of the nanostructures. It is found that the PTCDA nanofibers, nanoneedles, nanobelts, and nanorods are produced at 330 ℃Ts; Only nanorods are formed at 280 ℃, 230 ℃, and 180 ℃, and their lengths become short asTs decreases; the continuous films are obtained on 50 ℃ AAOs substrates. HRTEM and SAED results show that the nanoneedle and nanorods are of single crystal. According to SEM results, the formation of PTCDA nanostructures should be mainly affected by surface curvature andTs.