Chem. Mater., 2019, 31, 15, 5788–5795. https://pubs.acs.org/doi/abs/10.1021/acs.chemmater.9b01864

Finding new low-dimensional metal halides with broad-band emission is attracting interest in single-component phosphor for white light-emitting diodes (WLEDs). The full-spectrum white light still remains a challenge as found in the two-dimensional hybrid material (C₆H₁₈N₂O₂)PbBr₄ exhibiting the intrinsic free exciton (FE) and broad-band self-trap exciton (STE) emission upon 365 nm ultraviolet excitation, and a combined strategy has been proposed through doping the Mn²⁺ ions enabling a superposition of multiple emission centers toward the ultra-broad-band warm white light. The occupation of Mn²⁺ in (C₆H₁₈N₂O₂)PbBr₄ has been discussed, and optical investigations verify that the warm white-light emission of Mn²⁺-doped (C₆H₁₈N₂O₂)PbBr₄ originates from the coupling effects of the FE, STEs, and the ⁴T₁–⁶A₁ transition of the doped Mn²⁺. When the concentration of Mn²⁺ is 5%, the emission spectrum of the phosphor covers all visible-light areas with a full width at half maximum (FWHM) of about 230 nm. The high R_a (84.9) and warm light CCT (3577 K) values of the as-fabricated WLED lamp demonstrate that (C₆H₁₈N₂O₂)Pb_1–xMn_xBr₄ can be promising as single-component white-light phosphor in solid-state lighting. Our work could provide a new understanding and perspective about hybrid metal halides for designing superior phosphor toward single-component white emission.

https://onlinelibrary.wiley.com/doi/abs/10.1002/adom.201801435

The halide double perovskite family represented by A₂(B⁺,B³⁺)X₆ can overcome the lead toxicity and enable generally large band gap engineering via B/B sites’ transmutation or exotic dopants to fulfill the emerging applications in the optoelectronic fields. Herein, the design and the experimental synthesis of a new family of Mn²⁺-doped Cs₂NaBi_1-xIn_xCl₆ crystals with an intense orange-yellow emission band are reported, and the phase formation stability is discussed via a combined experimental–theoretical approach. Depending on the manipulation of Bi³⁺/In³⁺ combination, the band gap increases with In³⁺ content, and a subsequent evolution from indirect to direct band gap is verified. First-principles calculations and parity analyses indicate a parity forbidden effect on Cs₂NaInCl₆, and a combination effect of absorption on Cs₂NaBi_1-xIn_xCl₆ from both Cs₂NaBiCl₆ and Cs₂NaInCl₆. The associated Mn²⁺-doped photoluminescence depending on the Bi³⁺/In³⁺ substitution is also addressed from the variation of the different Mn–Cl environment and neighboring-cation effect.