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

Abstract Corrugated 2D antimony‐halide perovskites such as Cs 3 Sb 2 Cl 9 (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 Sb 3+ by a small amount of trivalent rare earth (RE) cations RE 3+ , the photoluminescence intensities from high‐quality Cs 3 (Sb 1− x RE x ) 2 Cl 9 (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 Cs 3 (Sb 0.995 Er 0.005 ) 2 Cl 9 film is 9.5% at RT, which is much higher than A 3 B 2 X 9 perovskites previously reported for single‐source white‐light lighting. Furthermore, the Cs 3 (Sb 0.995 Er 0.005 ) 2 Cl 9 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 Cs 3 Sb 2 Cl 9 and Cs 3 Er 2 Cl 9 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.