Hybrid Germanium Bromide Perovskites with Tunable Second Harmonic Generation

Liu Y.,Gong Y.-P., Geng S., Feng M.-L., Manidaki D., Deng Z., Stoumpos C. C., Canepa P., Xiao Z., Zhang W.-X., and Mao L.; Angew. Chem. (2022).

Abstract

Ge-based hybrid perovskite materials have demonstrated great potential for Second Harmonic Generation (SHG) due to the geometry and lone-pair induced non-centrosymmetric structures. Here, we report a new family of hybrid three-dimensional (3D) Ge-based bromide perovskites AGeBr3, A = CH33NH33 (MA), CH(NH2)2 (FA), Cs and FAGe0.5Sn0.5Br3, crystallizing in polar space groups. These compounds exhibit tunable SHG responses, where MAGeBr 3 shows the strongest SHG intensity (5 × Potassium Dihydrogen Phosphate, KDP). Structural and theoretical analysis indicate the high SHG efficiency is attributed to the displacement of Ge2+ and preferable alignment of polar MA + cations along the [111] direction. This work provides new structural insights for designing and fine-tuning the SHG properties in hybrid metal halide materials.