Fine‐Tuning Single‐Source White‐Light Emission from All‐Inorganic Corrugated 2D Antimony‐Halide Perovskite

Abstract Corrugated 2D antimony‐halide perovskites such as Cs₃Sb₂Cl₉ (CSC) are promising candidates for single‐source white‐light emission due to their ultra‐broadband spectra. However, CSC has a serious luminescence quenching phenomenon due to inadequate confinement of excitons. By the homovalent substitution of trivalent antimony cation Sb³⁺ by a small amount of trivalent rare earth (RE) cations RE³⁺, the photoluminescence intensities from high‐quality Cs₃(Sb_1−xRE_x)₂Cl₉ (CSRC) (RE = Ce, Sm, Nd, Y, Er, etc.) films at room temperature (RT) are over two orders of magnitude higher than that of CSC film. Especially, the photoluminescence quantum yield (PLQY) for the Cs₃(Sb_0.995Er_0.005)₂Cl₉ film is 9.5% at RT, which is much higher than A₃B₂X₉ perovskites previously reported for single‐source white‐light lighting. Furthermore, the Cs₃(Sb_0.995Er_0.005)₂Cl₉ film exhibits an ultra‐broadband emission with the full width at half maximum reaching 554 meV at RT, resulting in a “warm” white‐light with the CIE coordinate (0.33, 0.46) and the correlated color temperature of 5450 K. The PLQY enhancement can be considered as the fact that a high activation energy by bandgap widening effect and Type‐I‐like “straddling” band alignment between Cs₃Sb₂Cl₉ and Cs₃Er₂Cl₉ lead to reducing nonradiative losses and increasing radiative recombination channels. Meanwhile, the spectral broadening can be considered to be attributed to strong effect of electron–phonon interaction.