Luminescence in Sulfides: A Rich History and a Bright Future

Abstract

Sulfide-based luminescent materials have attracted a lot of attention for a wide range of photo-, cathodo- and electroluminescent applications. Upon doping with Ce3+ and Eu2+, the luminescence can be varied over the entire visible region by appropriately choosing the composition of the sulfide host. Main application areas are flat panel displays based on thin film electroluminescence, field emission displays and ZnS-based powder electroluminescence for backlights. For these applications, special attention is given to BaAl2S4:Eu, ZnS:Mn and ZnS:Cu. Recently, sulfide materials have regained interest due to their ability (in contrast to oxide materials) to provide a broad band, Eu2+-based red emission for use as a color conversion material in white-light emitting diodes (LEDs). The potential application of rare-earth doped binary alkaline-earth sulfides, like CaS and SrS, thiogallates, thioaluminates and thiosilicates as conversion phosphors is discussed. Finally, this review concludes with the size-dependent luminescence in intrinsic colloidal quantum dots like PbS and CdS, and with the luminescence in doped nanoparticles.

Temperature and wavelength dependent trap filling in M2Si5N8:Eu (M=Ca, Sr, Ba) persistent phosphors

“…For example, red persistent luminescence has been observed in CaS:Eu,Tm [15] and Ca 2 SiS 4 :Eu,Nd [16,17]. Recently, the family of alkaline earth nitrido-silicates, M 2 Si 5 N 8 :Eu (M = Ca, Sr, Ba) and their Tm-codoped variants were studied [10].…”

Rare earth doped core-shell particles as phosphor for warm-white light-emitting diodes

“…This relatively strong thermal quenching behavior is typical for (bulk) rare earth doped SrS, not only for the solvothermally prepared particles 10,15 . Ways to improve the thermal quenching behavior are currently being investigated.…”

“…Although in recent years considerable attention was devoted to the development of Eu 2+ and Ce 3+ doped (oxy)nitride phosphors [7][8][9] , rare earth doped alkaline earth sulfides are still valuable candidates for wavelength conversion of LEDs for lighting applications 10 . A disadvantage, however, is their limited stability against moist air, but this can be efficiently improved by covering the phosphor's surface with a protective coating 11 .…”

“…The quantum efficiency of Eu 2+ in Ca 1-x Sr x S was reported to be as high as 80% 15 , provided the dopant concentration can be kept low enough. Furthermore, Eu-doped binary sulfides have already been used as conversion phosphors for LEDs 10 . Similarly, the thermal quenching behavior is strongly influenced by the dopant concentration 15 .…”

Optical and structural properties of aluminium oxide thin films prepared by a non-aqueous sol–gel technique

“…Alkaline earth sulfide phosphors are very attractive for different areas such as display applications, electroluminescent devices and optical information storage. In addition, they are considered as very promising material for wavelength converter in light emitting diodes (LEDs) [19]. Notwithstanding, because of the limited stability with respect to water and other atmospheric components, it is not obvious to use sulfides as phosphor hosts.…”