Homo- and Heterovalent Doping-Mediated Self-Trapped Exciton Emission and Energy Transfer in Mn-Doped Cs₂Na_1–xAg_xBiCl₆ Double Perovskites

Abstract

Double perovskites exhibit low toxicity, intrinsic thermodynamic stability, and small carrier effective mass. Herein, a novel doping route was adopted to incorporate Mn ions into Cs2Na1–x Ag x BiCl6 double perovskites for engineering the band gap and tailoring the energy transfer. The as-prepared Cs2Na1–x Ag x BiCl6 (0 < x < 1) exhibited excellent photoluminescence and a broad self-trapped exciton (STE) band from 500 to 900 nm, which exhibited an abnormal emission peak blue shift with increasing temperature. For Mn-doped Cs2Na1–x Ag x BiCl6, the two photoluminescence (PL) bands from d–d transition emission of Mn ions and STEs were always observed simultaneously in the PL window. The distinct energy-transfer channel from the Mn2+ ion guest to the double-perovskite host resulted in the dominant Mn2+ emission. Our results will be helpful for further understanding the nature of the photophysics of double perovskites.

Halide Mixing and Phase Segregation in Cs2AgBiX6 (X = Cl, Br, and I) Double Perovskites from Cesium-133 Solid-State NMR and Optical Spectroscopy

“…The broad emission peak has been previously attributed to self-trapped excitonic species. 81 , 82 Cs 2 AgBiBr 6 prepared in an analogous way has an emission intensity which is ∼66 times lower than that of the pure chloride material and a similar broadband emission spectrum ( Figure 6 b, blue; Figure S19, Table S6 ). Bromide substitution into Cs 2 AgBiCl 6 leads to intermediate PL intensities: 19-fold and 41-fold reduction with respect to pure Cs 2 AgBiCl 6 for Br:Cl ratios of 1:5 and 2:4, respectively ( Figure 6 a).…”

Lead‐free metal halide perovskites for light‐emitting diodes

“…The hydrothermal method is also widely used in the synthesis of LFMHPs NCs and powders. 26,68,69 Typically, the precursors are firstly added in a polytetrafluoroethylene (PTFE) container and heated to a high temperature around 200 C to obtain an absolute dissolution and completely reacting. Thereafter, the temperature should be reduced in a controlled procedure to ensure ideal products could be created.…”

“…Thereafter, the temperature should be reduced in a controlled procedure to ensure ideal products could be created. 69 With this strategy, Tan et al 26 synthesized the double perovskite of Cs 2 Sn 0.89 Te 0.11 Cl 6 , which emitted a yellow-green luminescence with a wavelength of 580 nm and a high PLQY reaching 95.4%.…”

“…Typically, the precursors are firstly added in a polytetrafluoroethylene (PTFE) container and heated to a high temperature around 200°C to obtain an absolute dissolution and completely reacting. Thereafter, the temperature should be reduced in a controlled procedure to ensure ideal products could be created 69 . With this strategy, Tan et al 26 synthesized the double perovskite of Cs 2 Sn 0.89 Te 0.11 Cl 6 , which emitted a yellow‐green luminescence with a wavelength of 580 nm and a high PLQY reaching 95.4%.…”

Lead‐Free Halide Double Perovskites: Structure, Luminescence, and Applications

“…[ 178–180 ] Doping Mn 2+ can retain the cubic structure lattices, absorption edges, and direct bandgap of HDPs while imparting new optical emission in the orange–red region. [ 181–184 ] The Mn 2+ doping level can be as high as 1.5% in Cs 2 AgInCl 6 NCs and a bright orange emission is achieved with a high PL QY of 16%. [ 185 ] Layered quadruple HDP Cs 4 MnBi 2 Cl 12 SCs show enhanced orange–red emission of Mn 2+ with a PL QY up to 25.7% (Figure 12 d) benefiting from efficient energy transfer from adjacent BiCl 6 3− to the MnCl 6 4− octahedral in which the activation energy for this favorable energy transfer process is as low as 23 meV.…”