Persistent UV phosphors for application in photo catalysis

Gutiérrez-Martín, F.; Fernández-Martínez, Francisco; Dı́az, Paloma; Colón, C.; Alonso‐Medina, A.

doi:10.1016/j.jallcom.2010.04.178

Cited by 27 publications

(16 citation statements)

References 40 publications

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“…Persistent luminescence plays a role that may turn out to be vital to the developing field of photocatalysis and photovoltaics. The expanding interest in these domains is largely stimulated by economical and ecological advantages of using solar light as an abundant source of energy. − The Wang group synthesized CaAl 2 O 4 :Eu 2+ ,Nd 3+ @TiO 2 composite phosphors by a sol–gel method and validated their suitability for the degradation of nitrogen monoxide gas . This studies also support the idea that the phosphors can amass a considerable amount of the UV or visible light to be used for triggering photocatalytic reactions in the dark.…”

Section: Applicationsmentioning

confidence: 83%

Lanthanide-Activated Phosphors Based on 4f-5d Optical Transitions: Theoretical and Experimental Aspects

et al. 2017

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The synthesis of lanthanide-activated phosphors is pertinent to many emerging applications, ranging from high-resolution luminescence imaging to next-generation volumetric full-color display. In particular, the optical processes governed by the 4f-5d transitions of divalent and trivalent lanthanides have been the key to enabling precisely tuned color emission. The fundamental importance of lanthanide-activated phosphors for the physical and biomedical sciences has led to rapid development of novel synthetic methodologies and relevant tools that allow for probing the dynamics of energy transfer processes. Here, we review recent progress in developing methods for preparing lanthanide-activated phosphors, especially those featuring 4f-5d optical transitions. Particular attention will be devoted to two widely studied dopants, Ce and Eu. The nature of the 4f-5d transition is examined by combining phenomenological theories with quantum mechanical calculations. An emphasis is placed on the correlation of host crystal structures with the 5d-4f luminescence characteristics of lanthanides, including quantum yield, emission color, decay rate, and thermal quenching behavior. Several parameters, namely Debye temperature and dielectric constant of the host crystal, geometrical structure of coordination polyhedron around the luminescent center, and the accurate energies of 4f and 5d levels, as well as the position of 4f and 5d levels relative to the valence and conduction bands of the hosts, are addressed as basic criteria for high-throughput computational design of lanthanide-activated phosphors.

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Section: Applicationsmentioning

confidence: 83%

Lanthanide-Activated Phosphors Based on 4f-5d Optical Transitions: Theoretical and Experimental Aspects

et al. 2017

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“…The decay curve is then decomposed into multiple (three or more) exponential components, [22][23][24][25] frequently called "fast," "slow," or "intermediate," however, the time constants obtained in this way are often difficult to interpret physically and the large number of parameters involved can make the fitting procedure unreliable.…”

Section: Continuous Trap Depth Distributionsmentioning

confidence: 99%

Revealing trap depth distributions in persistent phosphors

et al. 2013

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Persistent luminescence or afterglow is caused by a gradual release of charge carriers from trapping centers. The energy needed to release these charge carriers is determined by the trap depths. Knowledge of these trap depths is therefore crucial in the understanding of the persistent luminescence mechanism. Unfortunately, the trap depths in persistent phosphors are often difficult to evaluate in an accurate and reliable way. The existing analysis methods are mostly based on single experiments, or they ignore the possibility of a continuous distribution of trap depths. We present a procedure to accurately probe the activation energies, even in the presence of a continuous distribution of energy levels. By performing a series of thermoluminescence experiments with varying excitation duration and at varying excitation temperature, and employing the initial rise analysis method, the depth and shape of such a distribution can be estimated. As an example, we investigated the trap system in the violet persistent phosphor CaAl 2 O 4 :Eu,Nd, and show that it consists of a Gaussian-shaped distribution of trap depths. The maximal density of traps lies in the region around 0.9 eV, but the distribution extends to 0.7 eV on the shallow side and 1.2 eV on the deep side. The described procedure can be used to obtain a clear view of the trap system in other persistent phosphors as well. This can lead to a better understanding of the nature of these trapping centers, and the role they play in the persistent luminescent mechanism.

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“…Ce 3+ -doped alkaline-earth aluminates MAl 2 O 4 (M = Ca, Sr, Ba) have been among the most studied Ce 3+ -doped materials, with PersL emission for over 3 h . More recently, UV-emitting PersL materials have been explored for their potential multifunctional applications, and several strategies have been presented to develop new emitters. − However, in these reports, the PersL emission is generally composed of a combination of ultraviolet (UV) and visible (VIS) bands. The contribution in the VIS band is expected to overlap significantly with the autofluorescence of the living tissues, which limits their real-time use as they require further optimization to separate two emissions: probe emission vs autofluorescence (see Supporting Information Figure S1).…”

Section: Introductionmentioning

confidence: 99%

Dynamics of Charges in Superlong Blacklight-Emitting CaB₂O₄:Ce³⁺ Persistent Phosphor

et al. 2019

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The optical and persistent luminescence properties of CaB2O4:Ce3+ phosphor are presented. The optical emission for excitation in the 250–340 nm wavelength region is dominated by two bands at 365 and 460 nm. Lifetime measurements suggested that the 365 nm emission band is due to interconfigurational Ce3+ 5d → 4f transitions. Upon excitation with a 254 nm UV lamp, a superlong persistent luminescence in the UVA1 region (340–400 nm, blacklight) was observed, lasting for at least 15 h, and with excellent reproducibility, which is perfectly suitable for phototherapy application. The initial-rise method was applied on the thermoluminescence glow curves to determine the trap distribution and trap depth. The results suggest that one distinct trap, with an activation energy of ∼0.52 eV, was solely responsible for the persistent luminescence in the CaB2O4:Ce3+ phosphor. The other traps had a quasi-continuous distribution, with activation energies between 0.56 and 1.15 eV. The proposed persistent luminescence and the thermoluminescence mechanisms are elucidated using experimental parameters obtained from the optical and thermoluminescence results and the theoretically calculated electronic structure of the Ce3+ ion in CaB2O4. The lowest Ce3+ 5d1 level was found to be ∼0.97 eV below the conduction band, and the persistent luminescence/thermoluminescence emission was dominated by the radiative transitions between Ce3+ energy levels, 5d → 2F5/2,7/2.

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Persistent UV phosphors for application in photo catalysis

Cited by 27 publications

References 40 publications

Lanthanide-Activated Phosphors Based on 4f-5d Optical Transitions: Theoretical and Experimental Aspects

Lanthanide-Activated Phosphors Based on 4f-5d Optical Transitions: Theoretical and Experimental Aspects

Revealing trap depth distributions in persistent phosphors

Dynamics of Charges in Superlong Blacklight-Emitting CaB₂O₄:Ce³⁺ Persistent Phosphor

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Persistent UV phosphors for application in photo catalysis

Cited by 27 publications

References 40 publications

Lanthanide-Activated Phosphors Based on 4f-5d Optical Transitions: Theoretical and Experimental Aspects

Lanthanide-Activated Phosphors Based on 4f-5d Optical Transitions: Theoretical and Experimental Aspects

Revealing trap depth distributions in persistent phosphors

Dynamics of Charges in Superlong Blacklight-Emitting CaB2O4:Ce3+ Persistent Phosphor

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Dynamics of Charges in Superlong Blacklight-Emitting CaB₂O₄:Ce³⁺ Persistent Phosphor