Dataset Information

Tunable molecular orientation and elevated thermal stability of vapor-deposited organic semiconductors.

ABSTRACT: Physical vapor deposition is commonly used to prepare organic glasses that serve as the active layers in light-emitting diodes, photovoltaics, and other devices. Recent work has shown that orienting the molecules in such organic semiconductors can significantly enhance device performance. We apply a high-throughput characterization scheme to investigate the effect of the substrate temperature (Tsubstrate) on glasses of three organic molecules used as semiconductors. The optical and material properties are evaluated with spectroscopic ellipsometry. We find that molecular orientation in these glasses is continuously tunable and controlled by Tsubstrate/Tg, where Tg is the glass transition temperature. All three molecules can produce highly anisotropic glasses; the dependence of molecular orientation upon substrate temperature is remarkably similar and nearly independent of molecular length. All three compounds form "stable glasses" with high density and thermal stability, and have properties similar to stable glasses prepared from model glass formers. Simulations reproduce the experimental trends and explain molecular orientation in the deposited glasses in terms of the surface properties of the equilibrium liquid. By showing that organic semiconductors form stable glasses, these results provide an avenue for systematic performance optimization of active layers in organic electronics.

SUBMITTER: Dalal SS

PROVIDER: S-EPMC4394295 | biostudies-literature | 2015 Apr

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Tunable molecular orientation and elevated thermal stability of vapor-deposited organic semiconductors.

Dalal Shakeel S SS Walters Diane M DM Lyubimov Ivan I de Pablo Juan J JJ Ediger M D MD

Proceedings of the National Academy of Sciences of the United States of America 20150323 14

Physical vapor deposition is commonly used to prepare organic glasses that serve as the active layers in light-emitting diodes, photovoltaics, and other devices. Recent work has shown that orienting the molecules in such organic semiconductors can significantly enhance device performance. We apply a high-throughput characterization scheme to investigate the effect of the substrate temperature (Tsubstrate) on glasses of three organic molecules used as semiconductors. The optical and material prop ...[more]

PMID: 25831545

Similar Datasets

Project description:During the nanoimprinting lithography (NIL) process, the role of solvent vapor in fabricating the pattern structure and inducing the molecular alignment of nanoimprinted polymer film has been attracting significant attention. We demonstrate here that the molecular orientation and thermal stability of poly(3-hexylthiophene) (P3HT) nanograting film can be affected obviously by the fabricated solvent vapor. A solvent-vapor nanoimprinting lithography (SV-NIL) technique based on a polydimethylsiloxane (PDMS) template is employed to fabricate a P3HT nanograting structure film successfully and solvent vapor is offered by chlorobenzene, chloroform and carbon disulphide, respectively. The molecular orientation of the polymer film is carefully characterized by grazing incidence wide angle X-ray diffraction (GIWAXD) measurements to investigate the effect of various solvent vapors on the molecular orientation of the P3HT nanograting film. For the P3HT nanograting film fabricated by chloroform and chlorobenzene solvent, the edge-on molecular orientation of the typical form II crystallographic structure is induced. However, this indicates that there are both the face-on molecular orientations of the form II and form I crystallographic conformation present for the P3HT nanograting film fabricated by carbon disulphide solvent. Therefore, the fabricated solvent vapor plays a significant role in determining the formation of the molecular orientation of the polymer nanostructure. Then, the role of thermal annealing in the stability of the molecular orientation was investigated for the P3HT nanograting film after a fixed temperature. As for the annealed nanograting film fabricated by chlorobenzene and chloroform solvent vapor, a single edge-on molecular orientation mode of the form I crystallographic structure has been obtained. However, for the annealed nanograting film fabricated by the carbon disulphide solvent, the edge-on and face-on molecular orientations of the form I crystallographic structure are still retained. This indicates that the stability of the form II crystallographic conformation is mainly dependent on the thermal annealing process. Therefore, after the annealing process, the final determining of the molecular alignment and crystallographic conformation depends significantly on the orientation type of the nanograting film before the annealing history, and it can be further inferred that the molecular orientation of the annealed polymer film is still affected by the fabricated solvent vapor significantly. Thus this will provide new understanding and guidance for the research of the topographical structure and molecular alignment of conjugated polymers.

Dataset Information

Tunable molecular orientation and elevated thermal stability of vapor-deposited organic semiconductors.

Publications

Tunable molecular orientation and elevated thermal stability of vapor-deposited organic semiconductors.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets