Adduct-Type Compounds for Nonlinear Optical Crystals

The performance prerequisites for nonlinear optical (NLO) crystals encompass a substantial second-harmonic generation (SHG), a considerable laser induced damage threshold, and a moderate degree of birefringence. Nevertheless, the presence of particular anions may result in deficiencies within certain properties. The utilization of mixed anionic groups has emerged as an effective strategy to achieve a balance among numerous performance parameters of NLO crystals, particularly in terms of SHG responses and bandgaps. Compared with other heteroanionic compounds, adduct-type compounds feature more concise structures with specific properties. Herein, we aim to provide an overview of the recent advancements in adduct-type NLO crystals, focusing on their structures and properties. Furthermore, we analyze the coordination chemistry and disadvantages involved in adducts, and discuss the current synthesis methods as well as future directions for further exploration. Adduct-type NLO crystals are distinguished by the direct combination of two components: halides and molecular cages (rings). Among these, polar phosphorus chalcogenide cages and symmetric rings are the predominant representatives. These adduct-type crystals possess a remarkable ability to achieve a harmonious balance among multiple property parameters, making them highly promising candidates for excellent IR NLO crystals.image

Automated summary

This article provides an overview of recent advancements in adduct-type nonlinear optical crystals, focusing on their structures and properties. The coordination chemistry and disadvantages of adducts are analyzed, and the current synthesis methods and future directions for further exploration are discussed. Adduct-type NLO crystals possess the ability to achieve a harmonious balance among multiple property parameters.