(C 4 H 10 NO)PbX 3 (X = Cl, Br): Design of Two Lead Halide Perovskite Crystals with Moderate Nonlinear Optical Properties.

Introducing electronegative species into organic constituents was considered to be one effective strategy for adjusting crystal symmetry and designing new nonlinear optical (NLO) materials. By substitution of C4 in piperidine (C 5 H 11 N) with electronegative oxygen, organic morpholine (C 4 H 9 NO) was easily obtained. Therefore, to design NLO crystals, we focused on combinations of stereochemically active lone-pair (SCALP) cation (Pb 2+ )-based chloride and bromide with morpholine molecules. In this work, two lead halide hybrid perovskite (C 4 H 10 NO)PbX 3 (X = Cl, Br, abbreviated as MPbCl 3 and MPbBr 3 , respectively) single crystals with moderate nonlinear optical properties were synthesized by a slow evaporation method. The two title crystals belong to orthorhombic space group P 2 1 2 1 2 1 with one-dimensional (1D) chainlike perovskite structures. Theoretical calculations revealed that the second harmonic generation (SHG) responses mainly originate from distorted {PbX 6 } octahedrons of the inorganic framework. Remarkably, moderate phase-matching SHG effects of about 0.70 and 0.81 times KH 2 PO 4 , large birefringences of 0.098 and 0.111 at 1064 nm, and large laser damage thresholds (LDTs) of 19.94 and 46.82 MW/cm 2 were estimated for MPbCl 3 and MPbBr 3 , respectively. This work provides a novel strategy for new purpose-designed hybrid NLO crystals by adjustment and modulation of chemical modification.