Tuning and Enhancing Nonlinear Optical Behavior in Hybrid Arylammonium Perrhenate Salts through Halogen Substitution

In the realm of optical and quantum computing, second-harmonic generation (SHG) serves as a valuable nonlinear optical element for both optical signal processing and quantum information processing. Herein, we report a series of innovative nonlinear optical (NLO) materials, denoted as (4-F-BTAB)ReO4, (4-Cl-BTAB)ReO4, and (4-Br-BTAB)ReO4 (BTAB = para-halobenzyltrimethylammoniun), which show illustrious high-contrast “off-on–off” SHG conversion over a broad temperature range. The precise halogen modification of cations not only achieves significant SHG signal intensity (1.08 × KDP–3.23 × KDP) but also elevates phase transition temperatures from 415.5 to 474.4 K. Notably, (4-Br-BTAB)ReO4 demonstrates a heightened SHG-active state with an increase of nearly 60 K, along with a wide band gap of 3.646 eV and enhanced piezoresponse performance of 2.25 V. This study contributes to the diversification of switchable NLO materials.