Narrow band 390 nm emitting phosphors for photoluminescent liquid crystal displays

Abstract

Photoluminescent liquid crystal displays use a liquid crystal to modulate the intensity of ultraviolet light incident on visible emissive phosphors. In order to gain optimum performance from the liquid crystal in such a device, the activating light must cover a narrow spectral bandwidth very near to the visible (violet) region of the spectrum. Calcium sulphate europium phosphor offers an emission spectrum closely matching these requirements and has been incorporated inside low pressure mercury cold cathode fluorescent lamps. These have been used to backlight a photoluminescent liquid crystal display demonstrator.

Luminescence of some Eu2+ activated bromides

“…BaMgAl 10 O 17 :Eu and Sr 5 (PO 4 ) 3 Cl:Eu are efficient tri-colour lamp phosphors [1,2], BaFBr:Eu is used as intensifier for X-ray imaging films [3] as well as for X-ray imaging using photo-stimulated luminescence (PSL) [4], CaSO 4 :Eu is near UV emitting phosphor for photoluminescent liquid crystal displays (PLLCD) [5], SrB 4 O 7 :Eu is an efficient phosphor for tanning lamps [6]. Use of SrMgAl 10 O 17 :Eu [7] and CaMgSi 2 O 6 :Eu [8] has been advocated as blue emitting component of a phosphor blend for plasma display panels (PDP).…”

Synthesis and properties of submicron range CaSO4:Eu particles

“…They also reported cathodoluminescence in CaSO 4 :Eu. CaSO 4 :Eu 2+ phosphor possessing narrow PL emission located near the UV-visible border was found to be suitable for application in photoluminescent liquid crystal displays [16]. CaSO 4 :Eu,Sm materials are prospective candidates for optical storage materials [17][18][19].…”

Effect of cation mixing on luminescence of Eu2+ in SrCl2

“…E.g. BaMgAl 10 O 17 :Eu and Sr 5 (PO 4 ) 3 Cl:Eu are efficient tri-colour lamp phosphors [1], BaFBr:Eu is used as intensifier for X-ray imaging films [2,3] as well as for X-ray imaging using photo-stimulated luminescence (PSL) [4], CaSO 4 :Eu is near UV-emitting phosphor for photoluminescent liquid crystal displays (PLLCD) [5]. Eu 2 + emission arises from the lowest band of 4f 6 5d 1 configuration to 8 S 7/2 state of 4f 7 configuration.…”