Sub-micron phase coexistence in small-molecule organic thin films revealed by infrared nano-imaging.

ABSTRACT: Controlling the domain size and degree of crystallization in organic films is highly important for electronic applications such as organic photovoltaics, but suitable nanoscale mapping is very difficult. Here we apply infrared-spectroscopic nano-imaging to directly determine the local crystallinity of organic thin films with 20-nm resolution. We find that state-of-the-art pentacene films (grown on SiO2 at elevated temperature) are structurally not homogeneous but exhibit two interpenetrating phases at sub-micrometre scale, documented by a shifted vibrational resonance. We observe bulk-phase nucleation of distinct ellipsoidal shape within the dominant pentacene thin-film phase and also further growth during storage. A faint topographical contrast as well as X-ray analysis corroborates our i

SUBMITTER: Westermeier C 

PROVIDER: S-EPMC4082641 | biostudies-literature | 2014 Jun

REPOSITORIES: biostudies-literature