Investigation of Highly Efficient Phosphors for Field Emission Displays

Field emission displays (FED) are new thin, flat displays，这可以恢复运动图片与快速反应。这是工作被探索恐惧症，which can meet the requirements of low-voltage, high-density electron excitation；(1) Oxides sufficient electrical conductivity and ruggedness as well as high efficiency.(1) Oxidescontaining elements with mixed valency.It was found that partial substitution of Al with either Gaor In In green-emitting Y - D23 - D2Al - D25 - D2O - D212 - D2：Tb decreases electrical resistivity of the phosphorresulting in suppression of electrical charging of the phosphor surface. Presumably mixed valency ofsuch elements as Ga, In or Ti increases the oxygen vacancy concentration，leading to a decrease in the resistivity.(2) Mechanism of efficiency improvement by additionIIIb-group element. addition of a IIIb-group element, e.g. Al，to a red-emitting phosphor SrTiO D23 - D2：Pr increases the luminescence efficiency by more than 200 times. This work has elucidMore ated two type of mechanism operating for this effect；(a) charge compensation between Pr - D13 - D1+ at Sr - D12 - D1+ sites and Al - D13 - D1+ at Ti - D14 - D1+sites and (b) elimination of planar faults in SrTiO D23 D2，crystals (thin SrO layers) formation of Sr-aluminates.An efficiency can be improved also in othercompounds with planar faultse.g. Ruddlesden-Popper phases. Similar Al-addition effect observed in SrIn D22 D2O D24 D2：1+ has been investigated based on the above consideration.(3) Feasibility of aconventional blue phosphor, ZnS: Ag, Al, as an FED phosphorA commercial CRT phosphor ZnS：Ag, Al has a high efficiencybut it shows considerable luminance saturation under high-density excitation. This work investigatedtraps, which possibly induce Auger process，主要非radiative process. Optical measurements show that deep impurity levels by Ag and Al areresponsible to the Auger process. the luminance saturation is therefore，caused by the factor inherent to the material composition. Less

Field emission displays (FED) are new thin, flat displays, which can reproduce moving pictures with fast response. This work has explored phosphors, which can meet the requirements of low-voltage, high-density electron excitation ; I.e. sufficient electrical conductivity and ruggedness as well as high efficiency.(1) Oxides containing elements with mixed valency.It was found that partial substitution of Al with either Ga or In in green-emitting YィイD23ィエD2AlィイD25ィエD2OィイD212ィエD2 : Tb decreases electrical resistivity of the phosphor, resulting in suppression of electrical charging of the phosphor surface. Presumably mixed valency of such elements as Ga, In or Ti increases the oxygen vacancy concentration, leading to a decrease in the resistivity.(2) Mechanism of efficiency improvement by addition of a IIIb-group element.Addition of a IIIb-group element, e.g. Al, to a red-emitting phosphor SrTiOィイD23ィエD2 : Pr increases the luminescence efficiency by more than 200 times. This work has elucid … More ated two types of mechanism operating for this effect ; (a) charge compensation between PrィイD13ィエD1+ at SrィイD12ィエD1+ sites and AlィイD13ィエD1+ at TiィイD14ィエD1+ sites and (b) elimination of planar faults in SrTiOィイD23ィエD2, crystals (thin SrO layers) by formation of Sr-aluminates.An efficiency can be improved also in other compounds with planar faults, e.g. Ruddlesden-Popper phases. Similar Al-addition effect observed in SrInィイD22ィエD2OィイD24ィエD2 : PrィイD13ィエD1+ has been investigated based on the above consideration.(3) Feasibility of a conventional blue phosphor, ZnS : Ag, Al, as an FED phosphorA commercial CRT phosphor ZnS : Ag, Al has a high efficiency, but it shows considerable luminance saturation under high-density excitation. This work investigated traps, which possibly induce Auger process, the main nonradiative process. Optical measurements show that deep impurity levels by Ag and Al are responsible to the Auger process. The luminance saturation is, therefore, caused by the factor inherent to the material composition. Less