Zn²⁺-Doped Lead-Free CsMnCl₃ Nanocrystals Enable Efficient Red Emission with a High Photoluminescence Quantum Yield

The toxicity of Pb and the instability of lead halide perovskites are the main obstacles to the practical application of lead-based nanocrystals (NCs). In this paper, all-inorganic Zn²⁺-doped lead-free perovskite (CsMn_1-ZnCl₃) NCs were synthesized by a hot-injection method. Mn²⁺ ions were partially replaced by Zn²⁺ ions, and the energy transfer between Mn²⁺ was effectively suppressed. Because of this, excitons are more advantageously confined to the [MnCl₆]^4- octahedron. Target CsMn_0.95Zn_0.05Cl₃ NCs were endowed with red emission at 654 nm with CIE coordinates of (0.70, 0.30) closing to the standard value of NTSC, and their photoluminescence quantum yield was increased to 77.1%, which is higher than those of Mn-based lead-free perovskites previously reported. Finally, a white light-emitting diode (LED) with adjustable emission from warm to cold white was realized by mixing Cs₃MnBr₅, CsMn_0.95Zn_0.05Cl₃, and a blue phosphor on a 382 nm ultraviolet LED chip.