Synergism of multiple functional chromophores significantly enhancing the birefringence in layered non-centrosymmetric chalcohalides

Abstract

Large birefringence is important and indispensable for laser technology to meet the application demands. However, it is still a challenge to obtain optical materials with large birefringence that can extend the commercial birefringent crystals. Herein, we present a birefringence screening and analysis system to explore high-performance optical materials by introducing multiple functional chromophores. Using the high-throughput screening methodology, optical materials with one or two functional chromophores were explored. In particular, the chalcohalides Hg₃AsQ₄X (Q = S or Se; X = Cl, Br, or I) with multiple functional chromophores were screened out using the density functional theory and high-throughput screening method. The results show that Hg₃AsQ₄X (Q = S or Se; X = Cl, Br, or I) have an extremely large birefringence (Δn: 0.391–0.493 at 1064 nm), two times that of the commercial birefringent crystal CaCO₃ (0.172 at 1064 nm). And novel birefringent material motifs activated by the synergism of the d¹⁰ cation Hg²⁺, the layer of lone pair electrons of As³⁺ cation, and the mixed anions Q²⁻/X⁻ (Q = S or Se; X = Cl, Br, or I) were found.