Fabrication of low-dimensional microstructures with distyrylbenzene derivatives

Abstract

Microneedle crystals of 1,4-bis-(4-methylstyryl)benzene (DSB-4Me) and amorphous microdots of bis (N,N-di-p-tolylamino-p-styryl)benzene (DADSB) are fabricated by using mask-shadowing and conventional vapor deposition techniques. By interaction between π-conjugated electronic chains and ionic lattice of a KCl crystal substrate, DSB-4Me molecules grow into needle crystals epitaxially orienting in four directions making ±60° against [110]KCl and [−110]KCl. As for DADSB, self-assembly into microdots by heating the KCl substrate at 180 °C during deposition is attributed to the impact of bulky peripheral groups in DADSB and surface migration of the deposited molecules. Moreover, while amplified spontaneous emission is observed above an excitation threshold of 362 μJ cm−2 in the DSB-4Me microneedle crystals, a lower threshold whispering-gallery mode lasing is observed above 37 μJ cm−2 for DADSB microdots owing to the higher waveguide quality.