A I B 3 II C 2 III Q 6 VI X VII : A Thioborate Halide Family for Developing Wide Bandgap Infrared Nonlinear Materials by Coupling Planar [BS 3 ] and Polycations

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2024-04, Vol.20 (16), p.e2308806
• Main Authors: Zhou, Jiazheng, Hou, Ketian, Chu, Yu, Yang, Zhihua, Li, Junjie, Pan, Shilie
• Format: Article
• Language: English
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202308806

Developing high-performance infrared (IR) nonlinear optical (NLO) materials is urgent but challenging due to the competition between NLO coefficient and bandgap in one compound. Herein, by coupling NLO-active [BS ] planar units and halide-centered polycations, six new metal thioborate halides ABa B S X (A = Rb, Cs; X = Cl, Br, I) composed of zero-dimensional [XBa Rb /Cs ] polycations and [BS ] units, belonging to a new family, are rationally designed and fabricated. The compounds show an interesting structural transition from Pbcn (ABa B S Cl) to Cmc2 (ABa B S Br and ABa B S I) driven by the clamping effect of polycationic frameworks. ABa B S Br and ABa B S I are the first series metal thioborate halide IR NLO materials, and the introduction of [BS ] unit effectively widens the bandgap of planar unit-constructed chalcogenides. ABa B S Br and ABa B S I, exhibiting wide bandgaps (3.55-3.60 eV), high laser-induced damage thresholds (≈ 6 × AgGaS ), and strong SHG effects (0.5-0.6 × AgGaS ) with phase-matching behaviors, are the promising IR NLO candidates for high-power laser applications. The results enrich the chemical and structural diversity of boron chemistry and give some insights into the design of new IR NLO materials with planar units.