Polarization‐Dependent Multiphoton‐Excited Self‐Trapped Emission in Alloyed 0D Rb₇Bi₃Cl₁₆ Metal Halides via Sb³⁺ Doping

Regulating the electronic structure by doping can promote photoluminescence emission of low-dimensional metal halides for developing white-light-emitting devices. Here, 0D metal halides Rb₇Bi₃Cl₁₆ have achieved a transition from nonluminescence to effective self-trapped excitons (STEs) emission after Sb³⁺ ion doping at room temperature. The femtosecond transient absorption spectrum reveals the nonradiative recombination was suppressed, whose lifetimes change from 93.9 ps to 3.6 ns after doping Sb³⁺ ion. Moreover, the Rb₇Bi₃Cl₁₆:Sb³⁺ exhibits polarization-dependent two-photon photoluminescence and three-photon photoluminescence in the excitation wavelength range of 900-1200 nm, which further confirmed that STEs emission is extrinsic STEs by lattice deformation rather than defects. This work suggests that Sb³⁺ ion doping can effectively improve the luminescence properties of low-dimensional metal halides and promote the application potential in high-order nonlinear photoelectric field.