Materials Science

A Gentle View of Organics

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Science  09 Mar 2012:
Vol. 335, Issue 6073, pp. 1149
DOI: 10.1126/science.335.6073.1149-b

The electronic properties of devices based on organic small molecules strongly depend on the architecture and organization of the active molecules, which can change over space and time. Thus, effective analytical probes must operate not only with fine temporal and spatial resolution but also over large sample sizes, without altering or damaging the specimens. Altoe et al. show that scanning transmission electron microscopy can be applied to the study of thin organic films. Damage to the samples is avoided through a low electron dose administered with scanned parallel beams, with the beam diameter determined by the sensitivity of the particular material. The authors mapped the structure of thin films of pentathiophene butyric acid (5TBA) and two of its derivatives. For Langmuir-Blodgett processed films of 5TBA, they observed islands approximately 1 µm in diameter, each comprising one or two crystalline domains with different lattice orientations. The authors also identified regions with lower diffraction intensity, which they associated with a high defect concentration—a factor of critical importance when troubleshooting poor performance in organic electronic devices.

Nano Lett. 12, 10.1021/nl203776n (2012).

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