Chiral Metal-Free Anti-Perovskite with Strong Chiroptical Nonlinearity

The nonlinear chiroptical properties of chiral metal halide perovskite has attracted substantial attention in recent years. In order to overcome the inherent limitations of metal halide, such as high costs, potential toxicity, challenges with recycling, especially the limited laser-induced damage threshold (LDT), we have successfully constructed the first chiral metal-free anti-perovskite, with the aim of utilizing it in second harmonic generation-circular dichroism (SHG-CD). Moreover, the anti-perovskite composed entirely of small organic ions typically display a more extensive transparent window, which could contribute a high LDT. Herein two chiral metal-free anti-perovskites, R/S-MCN [(R/S-MBA)₆Cl(NH₄Cl₆)] were constructed, and exhibit strong second-harmonic generation response from 800 to 980 nm. The second-order nonlinear optical coefficient of the chiral metal-free anti-perovskite reaches 0.89 pm/V, which is higher than that of commercial Y-cut quartz. Most importantly, both R- and S-MCN exhibit a large nonlinear optical activity with a high SHG dissymmetry factor (g_SHG-CD) of 0.60 and a high laser-induced damage threshold of 71 mJ/cm², which is higher than that of most reported chiral perovskites. Our findings indicate that chiral metal-free anti-perovskite have the potential to be a valuable addition to the development of next-generation nonlinear chiroptical devices.