Oxychalcogenides as Promising Ultraviolet Nonlinear Optical Candidates: Experimental and Theoretical Studies of AEGeOS<sub>2</sub>(AE = Sr and Ba)
Hedi Yang, Shenghua Zhou, Mao‐Yin Ran, Xintao Wu, Hua Lin, Qi‐Long Zhu
Abstract
Oxychalcogenides have gained widespread attention as promising infrared nonlinear optical (IR-NLO) candidates. However, high-performance oxychalcogenides have rarely been reported in the ultraviolet (UV) region owing to the low energy gaps (Eg < 4.0 eV). Herein, two non-centrosymmetric (NCS) oxychalcogenides with one-dimensional (1D) chain structures and wide Eg (>4.3 eV), namely, AEGeOS2 (AE = Sr and Ba), have been discovered by combined experiments and theory calculations as a new source of UV-NLO materials. Significantly, they exhibit excellent comprehensive performance comparable to the commercial UV-NLO material KH2PO4 (KDP), including large phase-matching ranges (>380 nm), sufficient second harmonic generation intensities (0.7–1.1 × KDP), high laser-induced damage thresholds (1.2 × KDP), wide transparent regions (0.26–12.2 μm), and good thermal stability (up to 1100 K). Moreover, systematic structure–activity relationship analysis illustrates that the 1D homochiral helical [GeOS2]2– chains composed of heteroanionic [GeS2O2] units make major contribution to the desirable UV-NLO performance. This work makes the two compounds shine out as new energy in the UV-NLO field and offers a new perspective for the exploration of structure-driven functional oxychalcogenides.