All‐Inorganic Manganese‐Based CsMnCl₃ Nanocrystals for X‐Ray Imaging

Abstract

Lead‐based halide perovskite nanomaterials with excellent optical properties have aroused great attention in the fields of solar cells, light‐emitting diodes, lasing, X‐ray imaging, etc. However, the toxicity of lead prompts researchers to develop alternatives to cut down the usage of lead. Herein, all‐inorganic manganese‐based perovskite derivatives, CsMnCl3 nanocrystals (NCs), with uniform size and morphology have been synthesized successfully via a modified hot‐injection method. These NCs have a direct bandgap of 4.08 eV and a broadband emission centered at 660 nm. Through introducing modicum lead (1%) into the CsMnCl3 NCs, the photoluminescence intensity greatly improves, and the quantum yield (PLQY) increases from 0.7% to 21%. Furthermore, the CsMnCl3:1%Pb NCs feature high‐efficiency of X‐ray absorption and radioluminescence, which make these NCs promising candidates for X‐ray imaging.

Mn4+-Doped Fluoride Nanocrystals Enable High-Resolution Red-Emitting X-ray Imaging Screens

“…To assess the light yield of our Cs 2 SnF 6 :Mn 4+ NCs, we used a commercial BGO single crystal with a light yield of 9000 photons/MeV as a reference, since Cs 2 SnF 6 and BGO have similar attenuation coefficients (Figure b). The light yield of Cs 2 SnF 6 :Mn 4+ NCs was estimated to be 3000 photons/MeV (Figure c), which is comparable with the previously reported values for CsPbI 3 NCs (5400 photons/MeV) and CsMnCl 3 :Pb NCs (2500 photons/MeV) . It should be noted that the lower light yield of Cs 2 SnF 6 :Mn 4+ NCs compared to that of the BGO standard is because of the sharp lines of Mn 4+ emission, leading to a weak integrated emission intensity.…”

Exciton Recombination versus Energy Transfer: Mapping Competing Excited-State Dynamics in Various Mn-Doped CsPb(Cl1–yBry)3 Perovskite Nanocrystals for Achieving White Light Emission

“…As the dopant concentration of Mn incorporated into CsPbCl 3 nanocrystals was well reported by previous literature precedence, there is a linear correlation of the blue shift in the excitonic peak as a function of the concentration of Mn determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). ,, More manganese ions are doped in the nanocrystals; the excitonic peaks of CsPbCl 3 nanocrystals with a band-edge absorption of 400 nm are shifted to a shorter wavelength due to the lattice contraction, resulting from the alloying of Pb with dopant Mn. , It is also worth noting that above x = 0.60, the significant blue shift of excitonic band-edge absorption is mainly due to the band gap change through alloying Pb/Mn. It has been reported that CsMnCl 3 has a direct band gap of 4.08 eV and through alloying Mn and Pb, the band gap can be tuned in the range of 4.08–2.19 eV . Increasing the Mn fraction ( x ) can somewhat improve the final doping concentration of Mn in the host lattices, while it is not very effective above a certain limit of the dopant concentration (> x = 0.65) since PL emission from Mn is saturated (Figure B).…”

“…It has been reported that CsMnCl 3 has a direct band gap of 4.08 eV and through alloying Mn and Pb, the band gap can be tuned in the range of 4.08−2.19 eV. 43 Increasing the Mn fraction (x) can somewhat improve the final doping concentration of Mn in the host lattices, while it is not very effective above a certain limit of the dopant concentration (> x = 0.65) since PL emission from Mn is saturated (Figure 1B). Both the slow cationic kinetic diffusion rate and high activation energy for cation vacancy formation hinder the doping of the cation in halide perovskite lattices as compared to the relatively facile halide-ion exchange.…”

High quality lead-free perovskites toward white light emitting diodes and X-ray imaging

“…6,7 However, the toxicity and stability problems of lead halide perovskites hinder their practical application for long-term operation. 8 Hence, the exploration of lead-free perovskites with high-performance has attracted particular attention based on the substitution of Pb 2+ ions with nontoxic metal elements (Sn 2+ , 9 Ge 2+ , 10 Mn 2+ , 11 Bi 3+ , 12 In 3+ , 13 and Sb 3+ 14–16 ). The as-explored inorganic lead-free metal halide perovskites (LFHPs) including CsSnCl 3 , 17 CsGeI 3 , 18 CsMnBr 3 , 19 Cs 3 Bi 2 Br 9 , 20 Cs 3 In 2 Br 9 , 21 and Cs 3 Sb 2 I 9 22 exhibit potential for ion detection, solar cells, anti-counterfeiting, information storage, lasers and photodetectors, respectively.…”