Growth defects of organic crystals: A review

During the growth of organic crystals, crystal defects can be formed. Microscopic defects, which include point, line, and planar defects, appearing as vacancies, growth dislocations, striations, and others, play an important role in the mechanical properties, optical properties, and electrical conductivity of organic crystals. In addition, macroscopic defects, such as fluid inclusions and cavities, may cause toxicity during crystal dehydration and degradation while favorable cavity defects can satisfy certain functions. Herein, this paper summarizes the growth defects of organic crystals from four perspectives; formation mechanism, characterization methods, control methods, and applications. We conclude three kinds of formation mechanism which are related to diffusion of solute molecules, impurities participating in the crystal growth, and structure of solute molecules respectively. Next, the characterization methods are exhibited from the perspectives of microscopy, spectroscopy, and others for different research areas. Then, we offer some control methods of defects which include adjustment of crystallization operation parameters, assistant of ultrasound and additives, irradiation, and ion implantation. As for applications, organic crystal defects have application potential in the fields of pharmacy and materials, for example, nonlinear optical materials, energetic materials, and semiconductor materials. Finally, we put forward the future outlooks on the growth defects of organic crystals.