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.; Mao, L.

doi:10.1002/anie.202208875

Hybrid Germanium Bromide Perovskites with Tunable Second Harmonic Generation

Y. Liu, Y.-P. Gong, S. Geng, M.-L. Feng, D. Manidaki, Z. Deng, C. C. Stoumpos, P. Canepa, Z. Xiao, W.-X. Zhang, and L. Mao; Angew. Chem. 61, e202208875 (2022).

BibTeX

@article{Liu2022hybrid,
  author  = {Liu, Y. and Gong, Y.-P. and Geng, S. and Feng, M.-L. and Manidaki, D. and Deng, Z. and Stoumpos, C. C. and Canepa, P. and Xiao, Z. and Zhang, W.-X. and Mao, L.},
  title   = {{Hybrid Germanium Bromide Perovskites with Tunable Second Harmonic Generation}},
  journal = {Angewandte Chemie International Edition},
  volume  = {61},
  pages   = {e202208875},
  year    = {2022},
  doi     = {10.1002/anie.202208875}
}

Brief summary

Germanium-based hybrid perovskites can convert light to twice its frequency (second-harmonic generation). We report a new family of 3D germanium bromide perovskites, the strongest, CH₃NH₃GeBr₃, five times the standard KDP, and trace their response to the shifted germanium atoms and their lone pairs of electrons.

Full 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 3D Ge-based bromide perovskites AGeBr₃, A=CH₃NH₃ (MA), CH(NH₂)₂ (FA), Cs and FAGe_0.5Sn_0.5Br₃, crystallizing in polar space groups. These compounds exhibit tunable SHG responses, where MAGeBr3 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⁺ along [111] direction and the relatively strong interactions between lone pair electrons of Ge²⁺ and polar MA cations along the c-axis. This work provides new structural insights for designing and fine-tuning the SHG properties in hybrid metal halide materials.