Insights into the complexity of the excited states of Eu-doped luminescent materials

Joos, Jonas; Smet, Philippe; Seijo, Luis; Barandiarán, Zoila

doi:10.1039/c9qi01455a

Cited by 57 publications

(67 citation statements)

References 125 publications

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“…2 ) is very similar as for the Eu 2+ luminescence, where the band can be identified, with a small redshift of 20 nm, corresponding to about 500 cm −1 . In addition to this band, some excitation intensity can be found in the region around 370 nm where no allowed transitions for Eu 2+ are found 31 , suggesting the presence of additional excited states when Eu and Tb are codoped. These features are also visible at low temperature, as well as in the diffuse reflectance spectra (see Supplementary Figs.…”

Section: Resultsmentioning

confidence: 96%

“…Singly Eu-doped MS shows the characteristic broadband emission, peaking ~650 and 615 nm for CaS and SrS, respectively. This band is attributed to the radiative de-excitation of the 4 f 6 5 d 1 states of Eu 2+ towards the 4 f 7 ( 8 S ) ground state 29 – 31 . The associated excitation spectrum as shown in Fig.…”

Section: Resultsmentioning

confidence: 97%

“…The associated excitation spectrum as shown in Fig. 2 consists of a very broad band, ranging from 410 to 610 nm, composed of numerous transitions towards the dense manifold 31 , 32 . No trace of Eu 3+ line emission is found.…”

Section: Resultsmentioning

confidence: 99%

“…2 ) 35 – 37 . In case of CaS and SrS, the fundamental absorption of the host lies in the same energy range, and the near-UV absorption and excitation bands are likely the result of a mixture of host- and dopant-related transitions 30 , 31 .…”

Section: Resultsmentioning

confidence: 99%

“…The excited state landscape of Eu 2+ was previously discussed in detail in ref. 31 and is practically defined by a single ground state level, 4 f 7 ( 8 S 7/2 ), separated from a very dense 4 f 6 5 d 1 manifold by ~16,000–17,000 cm −1 . Eu 3+ and Tb 3+ feature conjugate ground state configurations with 4 f 6 ( 7 F 0 ) and 4 f 8 ( 7 F 6 ) multiplets, respectively.…”

Section: Resultsmentioning

confidence: 99%

See 4 more Smart Citations

Broadband infrared LEDs based on europium-to-terbium charge transfer luminescence

Joos¹,

Heggen²,

Martin³

et al. 2020

Nat Commun

Self Cite

127

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Efficient broadband infrared (IR) light-emitting diodes (LEDs) are needed for emerging applications that exploit near-IR spectroscopy, ranging from hand-held electronics to medicine. Here we report broadband IR luminescence, cooperatively originating from Eu 2+ and Tb 3+ dopants in CaS. This peculiar emission overlaps with the red Eu 2+ emission, ranges up to 1200 nm (full-width-at-half-maximum of 195 nm) and is efficiently excited with visible light. Experimental evidence for metal-to-metal charge transfer (MMCT) luminescence is collected, comprising data from luminescence spectroscopy, microscopy and X-ray spectroscopy. State-of-the-art multiconfigurational ab initio calculations attribute the IR emission to the radiative decay of a metastable MMCT state of a Eu 2+ -Tb 3+ pair. The calculations explain why no MMCT emission is found in the similar compound SrS:Eu,Tb and are used to anticipate how to fine-tune the characteristics of the MMCT luminescence. Finally, a near-IR LED for versatile spectroscopic use is manufactured based on the MMCT emission.

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Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 3 more Smart Citations

Broadband infrared LEDs based on europium-to-terbium charge transfer luminescence

Joos¹,

Heggen²,

Martin³

et al. 2020

Nat Commun

Self Cite

127

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Giant Red‐Shifted Emission in (Sr,Ba)Y₂O₄:Eu²⁺ Phosphor Toward Broadband Near‐Infrared Luminescence

Yang

Zhao

Zhou

et al. 2021

Adv Funct Materials

161

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Near-infrared (NIR) light-emitting diodes (LEDs) light sources are desirable in photonic, optoelectronic, and biological applications. However, developing broadband red and NIR-emitting phosphors with good thermal stability is always a challenge. Herein, the synthesis of Eu 2+ -activated SrY 2 O 4 red phosphor with high photoluminescence quantum efficiency and broad emission band ranging from 540 to 770 nm and peaking at 620 nm under 450 nm excitation is designed. Sr/Ba substitution in SrY 2 O 4 :Eu 2+ has been further utilized to achieve tunable emission by modifying the local environment, which facilitates the giant redshifted emission from 620 to 773 nm while maintaining the outstanding thermal stability of SrY 2 O 4 :Eu 2+ . The NIR emission is attributed to the enhanced Stokes shift and crystal field strength originated from the local structural distortions of [Y1/Eu1O 6 ] and [Y2/Eu2O 6 ]. The investigation in charge distribution around Y/Eu provides additional insight into increasing covalency to tune the emission toward the NIR region. As-fabricated NIR phosphor-converted LEDs demonstration shows its potential in night-vision technologies. This study reveals the NIR luminescence mechanism of Eu 2+ in oxide-based hosts and provides a design principle for exploiting Eu 2+ -doped NIR phosphors with good thermal stability.

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Realizing Simultaneous X‐Ray Imaging and Dosimetry Using Phosphor‐Based Detectors with High Memory Stability and Convenient Readout Process

Yang

Heggen

et al. 2022

Adv Funct Materials

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Flexible X‐ray storage phosphor sheets are regarded as promising alternatives to conventional electronic flat‐panel X‐ray detectors, enabling X‐ray imaging and dosimetry in less accessible situations. However, it is a challenge to develop phosphor‐based detectors with high memory stability and convenient readout processes. Here, an approach to realize this using radiation‐induced photoluminescence tuning in (Ba1‐xSrx)2SiO4:Eu phosphors is demonstrated, ascribed to the reduction of Eu3+ toward Eu2+. The associated photoluminescence spectral change and the accompanying color contrast in response to the radiation dose are exploited for simultaneous X‐ray dosimetry and imaging. The recorded image can be read out conveniently by a regular photo camera upon UV illumination and the radiation dose can be extracted during the imaging process in a ratiometric way via the green to red pixel intensity, avoiding the need for absolute intensity measurement. Moreover, the imaged information can be maintained for longer than 28 days and the plate can be reused for X‐ray detection after bleaching upon 420 nm illumination, exhibiting superior memory retention ability and good cycling resistance. These results reveal the great potential of (Ba1‐xSrx)2SiO4:Eu for X‐ray‐based microbeam radiation therapy and nondestructive inspection and are expected to stimulate research on phosphor‐based photoluminescence modulated detectors.

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Insights into the complexity of the excited states of Eu-doped luminescent materials

Abstract: Multiconfigurational ab initio embedded-cluster methods give a detailed view of the excited states of Eu-doped luminescent materials, improving the understanding of their structure and how it is affected by changing the host's chemical composition.

Cited by 57 publications

References 125 publications

Broadband infrared LEDs based on europium-to-terbium charge transfer luminescence

Broadband infrared LEDs based on europium-to-terbium charge transfer luminescence

Giant Red‐Shifted Emission in (Sr,Ba)Y₂O₄:Eu²⁺ Phosphor Toward Broadband Near‐Infrared Luminescence

Realizing Simultaneous X‐Ray Imaging and Dosimetry Using Phosphor‐Based Detectors with High Memory Stability and Convenient Readout Process

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Insights into the complexity of the excited states of Eu-doped luminescent materials

Abstract: Multiconfigurational ab initio embedded-cluster methods give a detailed view of the excited states of Eu-doped luminescent materials, improving the understanding of their structure and how it is affected by changing the host's chemical composition.

Cited by 57 publications

References 125 publications

Broadband infrared LEDs based on europium-to-terbium charge transfer luminescence

Broadband infrared LEDs based on europium-to-terbium charge transfer luminescence

Giant Red‐Shifted Emission in (Sr,Ba)Y2O4:Eu2+ Phosphor Toward Broadband Near‐Infrared Luminescence

Realizing Simultaneous X‐Ray Imaging and Dosimetry Using Phosphor‐Based Detectors with High Memory Stability and Convenient Readout Process

Contact Info

Product

Resources

About

Giant Red‐Shifted Emission in (Sr,Ba)Y₂O₄:Eu²⁺ Phosphor Toward Broadband Near‐Infrared Luminescence