Partial Isovalent Anion Substitution to Access Remarkable Second-Harmonic Generation Response: A Generic and Effective Strategy for Design of Infrared Nonlinear Optical Materials

Abstract

Nonlinear optical (NLO) materials have received unprecedented attention owing to their capability of frequency conversion in the photoelectric fields. Yet, how to acquire a crystal with a noncentrosymmetric (NCS) structure is still a grand challenge for the NLO material. Herein, a new quaternary NCS oxychalcogenide, SrGeOSe2, was successfully designed and synthesized using the known centrosymmetric SrGeO3 as a maternal structure through a generic partial isovalent anion substitution (PIAS) strategy. SrGeOSe2 belongs to the NCS space group P212121 (no.19) and features a one-dimensional (1D) chain made by heteroligand [GeO2Se2] asymmetric building units. Such a new compound exhibits desirable comprehensive performance, which suggests a promising IR-NLO material: type-I phase-matching feature, strong powder second-harmonic generation intensity (dij = 1.3 × commercial AgGaS2), and giant powder laser-induced damage threshold (36 × commercial AgGaS2). Furthermore, the systematic theoretical investigations have been performed for the deep understanding of the correlation between the NCS structure and the NLO property. More importantly, this work pioneers a new molecular engineering strategy for NCS compounds that could be extended to other NLO materials.