Hierarchical molecular design of high-performance infrared nonlinear Ag2HgI4 material by defect engineering strategy

Mid-far infrared nonlinear optical (NLO) materials are gaining both scientific and technological interest in wide applications. The practical properties of one crystal are determined by its constituent atoms, electrons, lattices and their coupled interaction. Herein, by applying a hierarchical molecular design strategy, we synthesized a promising NLO material Ag2HgI4 by a simple solution method, which shows the strongest second harmonic generation (SHG) response in inorganic halides (4 x AgGaS2 (AGS)) and wide transparency range. The deep insights on nonlinearity enhancement and broadening transmittance were elaborated by theoretical calculations, which are attributed to reduced phonon frequency and increased nonbonding electronic states on top valence band. This physical mechanism is applicable in all NLO optical materials generally, opening a novel and exciting avenue for explorations of new NLO candidates with high performance. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

Mid-far infrared nonlinear optical (NLO) materials have attracted increasing scientific and technological interest due to their wide applications. Through hierarchical molecular design strategy, a promising NLO material Ag2HgI4 was synthesized by a simple solution method, showing strong second harmonic generation (SHG) response and wide transparency range. Theoretical calculations provided insights on nonlinearity enhancement and broadening transmittance, attributing to reduced phonon frequency and increased nonbonding electronic states on top valence band.