Organic Crystal Growth: Directly from Amorphous Solid Powder to Single Crystals

Abstract

Preparation of organic crystals mainly depends on solution-deposition, sublimation, and melt-deposition techniques. Solid-state growth methods are generally not suitable for organic crystal growth due to the unprocurable mass transfer. Herein, we report two pyridine-substituted fluorenone compounds with extraordinary crystal-growth capacity, and these compounds can directly and quickly form single crystals from their amorphous solid powder by heating under antisolvent-assistance conditions. The novel experimental phenomenon and crystal growth mechanism were investigated in depth. The results indicate that multiple intermolecular hydrogen-bonding sites and planar aromatic structure (prone to π-π interactions) of these molecules dominate the mass transfer during crystal growth by providing enough energy. This discovery enhances our knowledge of solid-state methods for singlecrystal growth.

Vapor‐Phase Growth Strategies of Fabricating Organic Crystals for Optoelectronic Applications

“…[64] However, crystals prepared by solution method are susceptible to the influence of solvent. In comparison, the vapor-phase methods have the following advantages: i) Some organic semiconductors exhibiting high performance, such as pentene and rubrene, are insoluble in common solvents, while the vapor-phase method can be directly conducted by using solid materials; [65,66] ii) The crystal grown in the liquid phase may be affected by the solvent, and the use of the vaporphase method can exclude the influence of the solvent or even the impurities in the raw material; [67,68] iii) It is easier to form high-quality crystals with high flatness by the direct assembly of vapor molecules. [69] Generally, the approach of transporting gaseous substances from a high-temperature region to a low-temperature region and assembling them into crystals is called the vapor-phase growth methods (Figure 2a).…”