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From AgGaSe2 to MIIGa2Se4 (MII = Zn, Cd): Heterovalent substitution creates ordered vacancies for balanced IR-NLO performance
Hong Chen, Zheng-Tao Hu b, Mao-Yin Ran, Zuju Ma*, Xin-Tao Wu, Hua Lin*
https://doi.org/10.1016/j.cjsc.2026.101108
MIIGa2Se4 (MII = Zn, Cd); IR nonlinear optical; Defect-diamond-like structure; Heterovalent substitution; Ordered vacancies
ABSTRACT
The concurrent achievement of strong second-harmonic generation (SHG) and high laser-induced damage threshold (LIDT) in a single infrared nonlinear optical (IR-NLO) material is fundamentally constrained by different electronic-structure requirements. Herein, we propose a heterovalent substitution strategy that introduces ordered cation vacancies to synergistically optimize the IR-NLO performance of famous chalcopyrite structure AgGaSe2. Guided by this design, we successfully synthesized two ternary defect-diamond-like selenides, MIIGa2Se4 (MII = Zn, Cd). Both compounds belong to the I space group and exhibit well balanced SHG coefficients and LIDT values: for ZnGa2Se4, 4.8 × AgGaS2 and 3.7 ×AgGaS2, respectively, ranking it among the best Zn-based IR-NLO materials reported to date; for CdGa2Se4, 2.5 × AgGaS2 and 3.2 ×AgGaS2, respectively, positioning them as promising IR-NLO candidates. Notably, the two compounds display distinctly different phase-matching behaviors at 2900 nm, where ZnGa2Se4 is phase-matchable whereas CdGa2Se4 is not, underscoring the profound impact of cation substitution on optical anisotropy. First-principles calculations based on the length-gauge formalism reveal that the synergistic effect of vacancy defects and the ordered alignment of tetrahedral [MIISe4] and [GaSe4] units serve as the main drivers of the enhanced SHG response. This work demonstrates that vacancy engineering within the chalcopyrite-derived diamond-like framework offers a viable route to mitigate the SHG–LIDT trade-off in IR-NLO chalcogenides.
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CN 35–1112/TQ, ISSN 0254–5861, Online ISSN: 2949-768X Copyright @ 2022 Chinese Journal of Structural Chemistry-www.Chinese Journal of Structural Chemistry.net. All Rights Reserved 闽ICP备2022002645号-1