Dual Emission in Organic–Inorganic (C₄H₁₂N)₂HfCl₆ Perovskites via the Invocation of Bi³⁺/Te⁴⁺ Octahedron Clusters

Zero-dimension (0D) lead-free metal halide perovskites have attracted great attention because of their outstanding photophysical properties. However, the development of tunable-color-temperature white-light emission in single perovskite phosphors is still a challenge. Herein, a dual-band tunable multicolor emitters based on ns 2 ions (Bi 3+ and Te 4+ ) codoped with a 0D hybrid perovskite derivative (C 4 H 12 N) 2 HfCl 6 is reported. The prepared (C 4 H 12 N) 2 HfCl 6:Bi 3+ /Te 4+ samples exhibit broad dual-band emission originating from the dopant self-trapped excitons of [BiCl 6 ] 3– and [TeCl 6 ] 2–, respectively. By virtue of the energy transfer from blue-emitting (Bi 3+ ) to yellow-emitting (Te 4+ ), tunable dual-emission white-light emission covering the entire visible region is achieved. Meanwhile, Bi 3+ /Te 4+ -codoped perovskites exhibit unique excitation-dependent emission, and a wide color gamut can be obtained by precisely controlling the excitation wavelength, which corresponds to the color hue evolution from warm white to blue, then to white, and finally to orange. These findings provide fundamental insight into multicolor emission in the Bi 3+ /Te 4+ -codoped systems and open up more opportunities for multifunctional applications.