Strong Nonlinear Response and All‐Optical Applications in Hybrid Bismuth Halide with Spatial Self‐Phase Modulation

Perovskite materials, known for their exceptional photoelectronic and photonic properties, have attracted considerable interest in the field of nonlinear optics (NLO). Herein, 0D organic–inorganic hybrid bismuth perovskite (PPA) 3 BiI 6 (PPA = 3‐phenyl‐2‐propen‐1‐ammonium) is successfully synthesized using the cooling‐induced crystallization method. The nonlinear optical responses of this hybrid bismuth halide are investigated within the visible spectrum range of 405–532 nm by the spatial self‐phase modulation (SSPM) method. It is found that (PPA) 3 BiI 6 exhibits excellent third‐order nonlinear susceptibilities (), up to 10 −8 e.s.u. at 405 nm, which is larger than those of reported lead‐free perovskites in previous research. The all‐optical switching experiment is conducted, effectively realizing phase modulation of light through light interaction. Moreover, a novel unidirectional NLO excitation diode with a (PPA) 3 BiI 6 /SnS 2 hybrid structure is demonstrated for spatially nonreciprocal propagation. The research discovered a lead‐free perovskite with superior nonlinear optical properties and systematically investigated its potential applications in photonic device technology.