Understanding grain growth mechanism of high-performance organic semiconducting DPh-DBTTT molecule

Journal
APPL PHYS LETT
Date
2017.12.05
Abstract
We report here our investigations of the grain-growth mechanism of diphenyl-dibenzothiopheno[6,5-b:6‘,5‘-f]thieno[3,2-b]thiophene (DPh-DBTTT) which was recently published as a high-performance organic semiconductor. By atomic force microscopy, it is detected that unconventional needle-like structures are grown on the surface of DPh-DBTTT thin films and theses structures are more dominant as the film- thickness increases and the film-deposited surface temperature decreases. In combination with the crystal structure simulations, the grazing incidence wide angle x-ray scattering data indicate that DPh-DBTTT molecules prefer an edge-on orientation near the interface between the substrate and DPh-DBTTT thin film, while the needle-like structures consist of a face-on arrangement of the molecules. We anticipate that this structural change originates from the large step-edge energy barrier (0.47 eV) of DPh-DBTTT molecules. Our findings would be highly precious to designing new high performance organic semiconducting materials and optimizing the condition of thin film deposition process.
Reference
Appl. Phys. Lett. 111, 233301 (2017)
DOI
http://dx.doi.org/doi.org/10.1063/1.4999966