Luminescence efficiency of cerium doped insulators: The role of electron transfer processes

Raukas, M.; Basun, S. A.; Schaik, Willem van; Yen, W. M.; Happek, U.

doi:10.1063/1.117286

Cited by 121 publications

(79 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is because Ce 3+ occupies the octahedral site of the strong crystal field of O 2− in the YAG host crystal. 15 The band at 225 nm is very weak because the upper 5d states of Ce 3+ in YAG have energies within the conduction band of the host and, therefore, excitation in these levels results mainly in quenching. 17 The 5d level of Ce 3+ populated by the transition occurring at 345 nm is just below the YAG conduction band and will also be quenched to some extent at room temperature.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Enhanced luminescence of Y3Al5O12:Ce3+ nanophosphor for white light-emitting diodes

Haranath¹,

Chander²,

Sharma³

et al. 2006

Applied Physics Letters

161

103

View full text Add to dashboard Cite

Results pertaining to the development of highly dispersible stand-alone particles of Ce 3+ -doped Y 3 Al 5 O 12 nanophosphor and their luminescence are presented. The yellow light-emitting nanophosphor was produced as a result of a single-step auto-combustion process, which requires no auxiliary annealing treatments prior to any practical application. The structure, photoluminescence, and chromaticity of the powder nanophosphor samples with the compositions Y ͑3−x͒ Al 5 O 12 : xCe 3+ ͑x = 0.01-1͒ are featured in the letter. The nanophosphor absorbs light efficiently in the visible region of 400-500 nm, and shows single broadband emission peaking at ϳ560 nm. The luminescence yield is almost analogous to the samples made from other conventional methods. Hence, it could be an apt candidate for generating white light when coupled to a blue light-emitting diode ͑ em = 450 nm͒.

show abstract

mentioning

confidence: 99%

“…The ground state of Ce 3+ is split into 2 F 7/2 and 2 F 5/2 with an energy difference 15 of about 2200 cm −1 . The next higher state originates from the 5d state and 4f-5d transitions are parity and spin allowed.…”

mentioning

confidence: 99%

Enhanced luminescence of Y3Al5O12:Ce3+ nanophosphor for white light-emitting diodes

Haranath¹,

Chander²,

Sharma³

et al. 2006

Applied Physics Letters

161

103

View full text Add to dashboard Cite

show abstract

“…2 was reported previously and has been attributed to the ionization of 5d states located within the conduction band and to a thermally stimulated process involving 5d states located just below the conduction band. 1 In previous studies on this and on other doped insulators, [3][4][5] the onset of the photocurrent at low temperature has been interpreted as representing the energy from the Ce 3ϩ ground state to the CB edge. By this method, a value of 3.5 eV was estimated for the Ce 1 ion in Lu 2 SiO 5 .…”

mentioning

confidence: 99%

“…For the 5d excited states of lanthanides, delocalization can result in the total quenching of the luminescence and appears to be directly related to the precise location of the exited 5d states relative to the intrinsic bands of the crystalline host. 1,2 One way of locating the impurity ion ground state relative to the conduction band ͑CB͒ edge is to deduce the photoionization threshold energy from the onset of photoconductivity. [3][4][5] These onsets, however, are inherently difficult to define and can be easily misinterpreted.…”

mentioning

confidence: 99%

Temperature dependent spectroscopic studies of the electron delocalization dynamics of excited Ce ions in the wide band gap insulator, Lu2SiO5

Kolk

Basun

Imbusch

et al. 2003

Applied Physics Letters

Self Cite

View full text Add to dashboard Cite

Electron delocalization processes of optically excited states of Ce 3ϩ impurities in Lu 2 SiO 5 were investigated by means of a temperature and spectrally resolved photoconductivity study. By monitoring separately the strength of the photocurrent resulting from excitation into each of the Ce 3ϩ 5d absorption bands, over a broad temperature region, three different delocalization processes, namely direct photoionization, thermal ionization, and tunneling, have been identified. The relative probabilities and temperature dependencies of each of these processes are discussed. The observed exponential temperature increase in the photocurrent, which spans six orders of magnitude, allows for the exact placement of the lowest energy 5d levels of the Ce 3ϩ ions within the band gap. For Lu 2 SiO 5 :Ce 3ϩ , the lowest 5d state is determined to be 0.45 eV below the conduction band edge. Electron delocalization processes involving optically excited transition metal (3d) or lanthanide (4 f ) impurity ions in wide band gap insulators play a central role in determining the utility of insulating materials in various technical applications, such as in scintillators, phosphors, and tunable solid state lasers. For the 5d excited states of lanthanides, delocalization can result in the total quenching of the luminescence and appears to be directly related to the precise location of the exited 5d states relative to the intrinsic bands of the crystalline host. 1,2 One way of locating the impurity ion ground state relative to the conduction band ͑CB͒ edge is to deduce the photoionization threshold energy from the onset of photoconductivity. 3-5 These onsets, however, are inherently difficult to define and can be easily misinterpreted. In this letter, we show that, instead of using the photoionization threshold energy, the energy level structure of the impurity ion can be determined with more precision using the temperature dependence of thermal ionization from the lowest 5d state to the CB edge.A 10ϫ10ϫ0.5 mm Ce-doped Lu 2 SiO 5 crystal was mounted between two 90% transparent nickel mesh electrodes and two sapphire plates. Photocurrents were measured with a femtoampere stability using a Keitley 6517A electrometer. 1000 V was applied across the electrodes using the stabilized voltage supply of the same electrometer. Temperature control was achieved by using a cold finger, liquid nitrogen, a cartridge heater, a thermocouple, and a proportional integral differential controller. Tunable monochromatic light was provided by a 300 W cw xenon lamp and a 0.15 m monochromator. Photoconductivity ͑PC͒ and photostimulated luminescence ͑PSL͒ excitation spectra were corrected for the spectral intensity distribution of the excitation source.Lu 2 SiO 5 :Ce 3ϩ has been studied extensively since its successful use as a scintillating material in positron emission tomography scanners. [6][7][8] It is useful to compare PC spectra with the absorption, excitation, and luminescence spectra. Both absorption and luminescence properties are dominated by the vibroni...

show abstract

“…The 5d-4f transitions are allowed through the electric dipole mechanism and, therefore, are generally very strong. Their quantum efficiency at room temperature (RT) is in principle high, apart from the cases in which photoionization occurs, i.e., escape of an electron to the conduction band [95,96].…”

Section: Blue Phosphorsmentioning

confidence: 99%

Inorganic Phosphor Materials for Lighting

2016

View full text Add to dashboard Cite

This chapter addresses the development of inorganic phosphor materials capable of converting the near UV or blue radiation emitted by a light emitting diode to visible radiation that can be suitably combined to yield white light. These materials are at the core of the new generation of solid-state lighting devices that are emerging as a crucial clean and energy saving technology. The chapter introduces the problem of white light generation using inorganic phosphors and the structureproperty relationships in the broad class of phosphor materials, normally containing lanthanide or transition metal ions as dopants. Radiative and non-radiative relaxation mechanisms are briefly described. Phosphors emitting light of different colors (yellow, blue, green, and red) are described and reviewed, classifying them in different chemical families of the host (silicates, phosphates, aluminates, borates, and non-oxide hosts). This research field has grown rapidly and is still growing, but the discovery of new phosphor materials with optimized properties (in terms of emission efficiency, chemical and thermal stability, color, purity, and cost of fabrication) would still be of the utmost importance.

show abstract

Luminescence efficiency of cerium doped insulators: The role of electron transfer processes

Cited by 121 publications

References 2 publications

Enhanced luminescence of Y3Al5O12:Ce3+ nanophosphor for white light-emitting diodes

Enhanced luminescence of Y3Al5O12:Ce3+ nanophosphor for white light-emitting diodes

Temperature dependent spectroscopic studies of the electron delocalization dynamics of excited Ce ions in the wide band gap insulator, Lu2SiO5

Inorganic Phosphor Materials for Lighting

Contact Info

Product

Resources

About