Noncentrosymmetric Tetrel Pnictides RuSi₄P₄ and IrSi₃P₃: Nonlinear Optical Materials with Outstanding Laser Damage Threshold

Abstract

Abstract Noncentrosymmetric (NCS) tetrel pnictides have recently generated interest as nonlinear optical (NLO) materials due to their second harmonic generation (SHG) activity and large laser damage threshold (LDT). Herein nonmetal‐rich silicon phosphides RuSi 4 P 4 and IrSi 3 P 3 are synthesized and characterized. Their crystal structures are reinvestigated using single crystal X‐ray diffraction and 29 Si and 31 P magic angle spinning NMR. In agreement with previous report RuSi 4 P 4 crystallizes in NCS space group P 1, while IrSi 3 P 3 is found to crystallize in NCS space group Cm , in contrast with the previously reported space group C 2. A combination of DFT calculations and diffuse reflectance measurements reveals RuSi 4 P 4 and IrSi 3 P 3 to be wide bandgap ( E g ) semiconductors, E g = 1.9 and 1.8 eV, respectively. RuSi 4 P 4 and IrSi 3 P 3 outperform the current state‐of‐the‐art infrared SHG material, AgGaS 2 , both in SHG activity and laser inducer damage threshold. Due to the combination of high thermal stabilities (up to 1373 K), wide bandgaps (≈2 eV), NCS crystal structures, strong SHG responses, and large LDT values, RuSi 4 P 4 and IrSi 3 P 3 are promising candidates for longer wavelength NLO materials.