Manipulation of Cl/Br transmutation in zero-dimensional Mn2+-based metal halides toward tunable photoluminescence and thermal quenching behaviors

Abstract

Low-dimensional-networked metal halides are attractive for the screening of emitters applied in solid-state lighting and displays, but the lead toxicity and poor stability are obstacles that must be overcome in industrial applications. Herein, we aim at the discovery of bright and stable photoluminescence in zero-dimensional (0D) Mn²⁺-based metal halides. By manipulation of Cl/Br transmutation, the nature of the halogen can be confirmed as a pivotal factor to tune the PL behaviors, and the optimum Mn²⁺ emission with a high PLQY of 99.8% and a short lifetime of 0.372 ms can be achieved in (C₂₄H₂₀P)₂MnBr₄. The thermal quenching behaviors have been discussed in depth, indicating that the synergistic effect of good chemical stability of organic groups, a long Mn⋯Mn distance of 10.447 Å and a relatively large activation energy (ΔE = 0.277 eV) provides a platform for achieving excellent thermal stability in (C₂₄H₂₀P)₂MnBr₄. Moreover, the as-fabricated white LED device with a high luminous efficacy of 118.9 lm W⁻¹ and a wide color gamut of 105.3% National Television System Committee (NTSC) shows that (C₂₄H₂₀P)₂MnBr₄ can be employed as a desirable narrow-band green emitter for LED displays. This work provides a new understanding of fine tailoring halogens, and proposes a feasible approach to achieving high thermal stability emitters toward the targeted practical applications.