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The magnetic fields in substituted hexabenzocoronenes (HBC) are effective for producing oriented films of discotic liquid-crystalline materials, which allows the investigation of structure-property relationships in magnetically aligned films formed in field-effect transistor structures in a noninvasive, contact-free way. Since the magnetic field alignment is applicable to a wide range of self-assembled systems, this approach can be used for optimizing the properties of functional materials.

We report transport of electron-hole complexes in semiconductor quantum wells under applied electric fields. Negatively charged excitons ([X.sup.-]), created by laser excitation of a high electron mobility transistor, are observed to drift upon applying a voltage between the source and drain. In contrast, neutral excitons do not drift under similar conditions. The [X.sup.-] mobility is found to be as high as 6.5 X [10.sup.4] [cm.sup.2] [V.sup.-1] [s.sup.-1]. The results demonstrate that [X.sup.-] exists as a free particle in the best-quality samples and suggest that light emission from opto-electronic devices can be manipulated through exciton drift under applied electric fields., The exciton, the bound state resulting from the Coulomb attraction of an optically excited electron-hole pair, is often described as the semiconductor analog of the hydrogen atom. In 1958, Lampert [...]