Cs₃ Pb₂ (CH₃ COO)₂ X₅ (X=I, Br): Halides with Strong Second-Harmonic Generation Response Induced by Acetate Groups

Area of Science:

• Materials Science
• Solid-State Chemistry
• Nonlinear Optics

Background:

• Nonlinear optical (NLO) crystals are crucial for solid-state laser technology.
• Developing efficient second-harmonic generation (SHG) materials is an ongoing research area.
• Lead halide perovskites offer potential for NLO applications but require tailored synthesis.

Purpose of the Study:

• To synthesize novel lead halide perovskites with enhanced SHG properties.
• To investigate the structural and optical characteristics of the new materials.
• To explore their potential as NLO crystals for laser applications.

Main Methods:

• Rational synthesis of Cs3Pb2(CH3COO)2X5 (X=I, Br) via solvothermal conditions.
• Introduction of acetate groups into lead halide perovskite structures.
• Theoretical studies and dipole moment calculations to understand SHG origins.
• Experimental characterization of SHG response, birefringence, and laser damage threshold (LDT).

Main Results:

• Successful synthesis of Cs3Pb2(CH3COO)2X5 (X=I, Br) featuring oriented anionic chains.
• SHG effects attributed to distorted [PbX4O2] polyhedrons.
• Cs3Pb2(CH3COO)2I5 shows strong phase-matching SHG (8xKDP) and high birefringence (0.26 @ 1064 nm).
• Materials exhibit significantly high LDT, 27x and 41x greater than AgGaS2 for X=I and Br, respectively.

Conclusions:

• The new Cs3Pb2(CH3COO)2X5 (X=I, Br) materials are promising candidates for NLO applications.
• The incorporation of acetate groups effectively enhances SHG performance.
• These materials possess superior properties compared to existing NLO crystals, particularly in LDT.