One-minute self-assembly of millimetre-long DAST crystalline microbelts via substrate-supported rapid evaporation crystallization

Abstract

In this work, we propose a substrate-supported rapid evaporation crystallization (SSREC) method to rapidly self-assemble microbelts of 4-N,N-dimethylamino-4′-N′-methyl-stilbazolium tosylate (DAST), a benchmark organic nonlinear optical (NLO) crystal. The DAST microbelts formation depends very largely on substrate property and surfactant, and millimetre-long microbelts can be fabricated in less than one minute. The self-assembly driving forces are presumed to be the coulombic interactions which originate from DAST's ionic molecular structure and the large dipole moment of DAST nanocrystals. The DAST microbelt has a second harmonic generation active crystal structure and exhibits featured absorption and fluorescent properties. We believe that all these findings will facilitate applications of DAST in a very broad range of areas such as integrated light modulation, lasing etc. Furthermore, the simplicity of the SSREC may open new avenues in the area of organic NLO one-dimensional materials fabrication.