Highly Efficient and Tunable Emission of Lead‐Free Manganese Halides toward White Light‐Emitting Diode and X‐Ray Scintillation Applications

Abstract

Environmental friendly metal halides have become emerging candidates as energy downconverting emitters for lighting and X-ray imaging applications. Herein, luminescent single crystals of tetramethylammonium manganese chloride (C 4 H 12 NMnCl 3 ) and tetraethylammonium bromide ((C 8 H 20 N) 2 MnBr 4 ) are synthesized via a facile room-temperature evaporation method. C 4 H 12 NMnCl 3 and (C 8 H 20 N) 2 MnBr 4 with octahedrally and tetrahedrally coordinated Mn 2+ have correspondingly exhibited red and green emission peaking at 635 and 515 nm both originating from 4 T 1 -6 A 1 transition of Mn 2+ with high photoluminescence quantum yield (PLQY) of 91.8% and 85.1% benefiting from their specific crystal structures. Thanks to their strong photoexcitation under blue light, high PLQY, tunable emission spectra, good environmental stability, the white light-emitting diode based on blending of C 4 H 12 NMnCl 3 and (C 8 H 20 N) 2 MnBr 4 delivers an outstanding luminous efficacy of 96 lm W −1 , approaching commercial level, and shows no obvious photoluminescence intensity degradation after 3000 h under operation. In addition, manganese halides also demonstrate interesting characteristics under X-ray excitation, C 4 H 12 NMnCl 3 and (C 8 H 20 N) 2 MnBr 4 exhibit steady-state X-ray light yields of 50 500 and 24 400 photons MeV −1 , low detectable limits of 36.9 and 24.2 nGy air s −1 , good radiation hardness, and X-ray imaging demonstration with high-resolution of 5 lp mm −1 . This work presents a new avenue for luminescent Mn-based metal halides toward multifunctional light-emitting applications.

Organic−Inorganic Manganese Bromide Hybrids with Water‐Triggered Luminescence for Rewritable Paper

“…Manganese(II) has long been used as excellent photoluminescent centers due to the spin-forbidden d-d transition from 4 T 1 excited state to 6 A 1 ground state, in which the absorption and emission behaviors can be modulated by its coordination environment. [8] Generally, tetrahedrally and octahedrally coordinated Mn 2+ correspondingly present green and red emissions, respectively. [9] Several organic manganese halide hybrids, (C 9 NH 20 ) 2 MnBr 4 (C 9 NH 20 , 1-buty-1-methylpyrrolidinium), PEA 2 MnBr 4 (PEA, phenethylamine), [Ph 4 P] 2 MnBr 4 (Ph 4 P, tetraphenylphosphonium), (C 5 H 6 N) 2 MnBr 4 and C 5 H 6 NMnCl 3 (C 5 H 6 N, pyridine), etc., have widely been used as effective light emitters in chemical sensing and light-emitting diodes.…”

Cesium Lead Halide Nanocrystals based Flexible X‐Ray Imaging Screen and Visible Dose Rate Indication on Paper Substrate

“…Between them, indirect detectors emerged as the mainstream method due to its mature fabrication process, robust nature, and convenient operation. [ 3 ] Generally, scintillators utilize X‐ray photon mainly through photoelectronic effect and Compton scattering and generate lots of secondary electrons, then emitting low‐energy photons for further imaging. [ 4 ] In this case, scintillator plays a decisive role in determining the final performance of the detectors.…”

Coordination units of Mn2+ modulation toward tunable emission in zero-dimensional bromides for white light-emitting diodes

“…21,22 Octahedrally coordinated Mn 2+ shows an orange to red emission with a large full width at half maximum (FWHM 4 60 nm), while tetrahedrally coordinated Mn 2+ exhibits a green-yellow emission (500-550 nm) with a small FWHM of 25-60 nm. [23][24][25][26][27] So far, Mn 2+ -doped metal halides with orange-red emissions have been reported the most, [28][29][30][31][32][33][34] but unfortunately, they cannot be well applied in the field of solid-state lighting due to the shortcoming that almost all of them cannot be excited by blue light, resulting in a low efficiency for white LED devices. Most of the Mn 2+ -based OIMHs exhibit a narrow-band green emission.…”