Highly Anisotropically Self-Assembled Structures ofpara-Sexiphenyl Grown by Hot-Wall Epitaxy

Abstract

Highly anisotropic films of needle‐like crystallinepara‐sexiphenyl (PSP)—a promising candidate for the electroactive layer in organic light‐emitting diodes (LEDs)—can be produced using hot‐wall epitaxy, as demonstrated here (see Figure). Optical dichroic ratios of ≈11 in absorption and up to 14 in emission are measured, which is of great significance for the development of polarized LEDs.

Epitaxial growth of sexithiophene on mica surfaces

“…7 In the broad spectrum of available material systems, the epitaxial growth of molecular assemblies on various substrates has been thoroughly investigated and identified as a promising basis for numerous device applications in the field of organic electronics. In this context, the growth of rodlike organic molecules on muscovite mica substrates has been extensively studied [9][10][11][12][13][14] and, in particular, phenylenes have been recognized as key materials for a large number of optical applications, e.g., lasing and wave guiding, 15 due to their advantageous ability to form highly parallel organic nanofibers. To broaden the spectrum of optical applications the phenylene oligomers should be substituted by other rodlike molecules, e.g., acenes or thiophenes, 3,13 which presupposes a detailed knowledge concerning epitaxial growth.…”

Self‐Waveguided Photoemission and Lasing of Organic Crystalline Wires Obtained by an Improved Expitaxial Growth Method

“…[9][10][11] As generally known a longer thiophene sequence leads to higher luminescence performance and color varieties. However, there is no report on epitaxial growth, which is a potential method to prepare highly oriented molecular crystalline materials on a substrate, [12][13][14][15][16] for thiophene derivatives containing three or more repetitions of thiophene units, to the best of our knowledge. As mentioned above, here we demonstrate the epitaxial preparation of highly oriented molecular crystalline wires and the characteristic photonic properties of BP3T.…”

Random laser action in self-organized para-sexiphenyl nanofibers grown by hot-wall epitaxy

“…6 In recent years, various groups have fabricated self-organized crystalline nanofibers of oligo-phenylenes with the potential for future applications in photonics as nanoscale laser sources. [8][9][10] Investigations of the nonlinear optical response of oligo-phenylene nanofibers have shown so far only evidence of spectral narrowing.…”

“…12 Importantly, the alignment of the p-6P long molecular axes is nearly the same in all domains-practically parallel to the substrate and perpendicular to the fiber direction. 9,12 Such a uniform alignment of molecules reflects in very high dichroic ratios of p-6P nano-fibers-up to 14 in absorption and emission, 9 as well as in waveguiding behavior of single nanofibers. 13 Samples with different quantities of deposited material are grown, resulting in nanofibers with different average heights, ranging from 100 to 400 nm.…”