Hybrid Germanium Bromide Perovskites with Tunable Second Harmonic Generation

Area of Science:

• Materials Science
• Solid-State Chemistry
• Crystallography

Background:

• Germanium-based hybrid perovskites are promising for nonlinear optics.
• Non-centrosymmetric structures and lone-pair electrons are key for second harmonic generation (SHG).

Purpose of the Study:

• To explore a new family of 3D Ge-based bromide perovskites.
• To investigate their potential for tunable second harmonic generation (SHG).

Main Methods:

• Synthesis and crystallization of AGeBr3 and FAGe0.5Sn0.5Br3 compounds.
• Characterization of crystallographic structures in polar space groups.
• Measurement and analysis of second harmonic generation (SHG) intensities.
• Theoretical calculations to understand structure-property relationships.

Main Results:

• A new family of polar hybrid 3D Ge-based bromide perovskites (AGeBr3) was synthesized.
• Compounds exhibited tunable SHG responses, with methylammonium germanium bromide (MAGeBr3) showing the strongest intensity (5× KDP).
• High SHG efficiency is linked to Ge2+ displacement and lone-pair electron interactions.

Conclusions:

• The discovered Ge-based perovskites are efficient nonlinear optical materials.
• Structural insights reveal mechanisms for enhancing SHG properties.
• This research guides the design of novel hybrid metal halide materials for optical applications.