| Autor: |
Gonzalez Arellano DL; Department of Polymer Science and Engineering , University of Massachusetts Amherst , Amherst , Massachusetts 01003 , United States., Burnett EK; Department of Polymer Science and Engineering , University of Massachusetts Amherst , Amherst , Massachusetts 01003 , United States., Demirci Uzun S; Department of Polymer Science and Engineering , University of Massachusetts Amherst , Amherst , Massachusetts 01003 , United States., Zakashansky JA; Department of Polymer Science and Engineering , University of Massachusetts Amherst , Amherst , Massachusetts 01003 , United States., Champagne VK 3rd; Department of Polymer Science and Engineering , University of Massachusetts Amherst , Amherst , Massachusetts 01003 , United States., George M; Department of Polymer Science and Engineering , University of Massachusetts Amherst , Amherst , Massachusetts 01003 , United States., Mannsfeld SCB; Center for Advanced Electronics Dresden , Dresden University of Technology , Dresden 01062 , Germany., Briseno AL; Department of Polymer Science and Engineering , University of Massachusetts Amherst , Amherst , Massachusetts 01003 , United States.; Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16803 , United States. |
| Abstrakt: |
We report on the graphene-assisted growth, crystallization, and phase transition of zinc phthalocyanine (ZnPc) vertically oriented single crystal nanopillars. Postcrystallization thermal annealing of the nanostructures results in a molecular packing change while maintaining the vertical orientation of the single crystals orthogonal to the underlying substrate. Grazing incidence X-ray diffraction and high-resolution TEM studies characterized this phase transition from a metastable crystal phase to the more stable β-phase commonly observed in bulk crystals. These vertical arrays of crystalline nanopillars exhibit a high-surface-to-volume ratio, which is advantageous for applications such as gas sensors. We fabricated chemiresistor sensors with ZnPc nanopillars grown on graphene and demonstrated its selectivity for ammonia vapors, and improvement in sensitivity in the β-phase crystal packing pillars due to their molecular orientation increasing the exposure of the Zn 2+ ion to the ammonia analyte. This work highlights the first morphology-retentive phase transition in organic single crystal nanopillars through simple postprocessing thermal annealing. This study opens up the possibility of molecular packing control without large variations in morphology, a necessity for high-performance devices and establishing structure-property relations. |
