Research Progress on Organic Cocrystals Nonlinear Optics Materials and Applications

With the appearance of second harmonic generation (SHG) and two-photon absorption (TPA), organic nonlinear optical (NLO) materials have played an increasingly important role in laser frequency conversion, biological imaging, micro-nano processing, optical limiting, terahertz wave (THz) and other fields in the past decades, arousing widespread interest. So far, most of the organic nonlinear optical active materials reported are single component which chemical synthesis is cumbersome, experimental conditions are rigorous and it is difficult to break the limit of the inherent properties of the single component. While organic composite material can rapidly broaden the variety of materials through simple forms such as blending, doping and cocrystallization, organic cocrystals based on intermolecular non-covalent interactions through more than one molecule have been developed to a large extent towards tuning and modifying the physicochemical properties of molecular solids. However, there is no systematic introduction of organic cocrystals in nonlinear optics at home and abroad. Firstly, the second-order and third-order nonlinear optical performance parameters and their testing methods are introduced; then, the latest research progress of molecular cocrystals materials in this field is introduced, including the types of materials, preparation methods, and the mechanism of optical nonlinearity effect; next, the possible applications of cocrystals nonlinear optical materials are discussed. Finally, some prospects for the development of this field are provided, and it is believed that this review can provide some reference for researchers in the field of organic cocrystals and nonlinear optics.