Alternative Face-on Thin Film Structure of Pentacene

[ABSTRACT] Pentacene attracts a great deal of attention as a basic material used in organic thin-film transistors for many years. Pentacene is known to form a highly ordered structure in a thin film, in which the molecular long axis aligns perpendicularly to the substrate surface, i.e., end-on orientation. On the other hand, the face-on oriented thin film, where the molecular plane is parallel to the substrate, has never been found on an inert substrate represented by SiO2. As a result, the face-on orientation has long been believed to be generated only on specific substrates such as a metal single crystal. In the present study, the face-on orientation grown on a SiO2 surface has first been identified by means of visible and infrared p-polarized multiple-angle incidence resolution spectrometry (pMAIRS) together with two-dimensional grazing incidence X-ray diffraction (2D-GIXD). The combination of the multiple techniques readily reveals that the face-on phase is definitely realized as the dominant component. The face-on film is obtained when the film growth is kinetically restricted to be prevented from transforming into the thermodynamically stable structure, i.e., the end-on orientation. This concept is useful for controlling the molecular orientation in general organic semiconductor thin films.

https://opac.ll.chiba-u.jp/da/curator/108509/

https://opac.ll.chiba-u.jp/da/curator/108509/sci_rep_9-579.pdf

Nature Research

学術雑誌論文

2045-2322

Scientific Reports

9

579

2019-01-24

10.1038/s41598-018-37166-6

publisher

(C) The Author(s) 2019