Inorganic TFEL display element and manufacturing method
An inorganic thin film electroluminescent display element having a layer structure comprising: a first dielectric layer, a luminescent layer, comprising a luminescent material, on the first dielectric layer, and a second dielectric layer on the luminescent layer. Each of the first and the second dielectric layers comprises nanolaminate with alternating aluminum oxide Al 2 O 3 and hafnium oxide HfO 2 sub-layers, the nanolaminate having at least two sub-layers of both types and a thickness of less than or equal to 300 nm.
1. An inorganic thin film electroluminescent display element having a layer structure comprising:
a first dielectric layer;
a luminescent layer comprising a luminescent material on the first dielectric layer; and
a second dielectric layer on the luminescent layer,
wherein each of the first and the second dielectric layers comprises nanolaminate with alternating aluminum oxide Al 2 O 3 and hafnium oxide HfO 2 sub-layers, the nanolaminate having at least two sub-layers of both types,
wherein the nanolaminate of at least one of the dielectric layers comprises at least ten HfO 2 sub-layers each having a thickness in a range of 0.5 to 3 nm.
2. The electroluminescent display element of claim 1 ,
wherein the nanolaminate has a thickness of less than or equal to 300 nm.
3. The electroluminescent display element of claim 1 , wherein a HfO2 sub-layer has a thickness in a range of 1 to 10 nm.
4. The electroluminescent display element of claim 1 , wherein an Al 2 O 3 sub-layer has a thickness in a range of 1 to 10 nm.
5. The electroluminescent display element of claim 1 , wherein a hafnium content of one or both the first or the second dielectric layer is at least 10% by mass.
6. The electroluminescent display element of claim 5 , wherein, in one or both the first or second dielectric layer where the hafnium content is at least 10%, an aluminum content is at least 5% by mass.
7. The electroluminescent display element of claim 1 , wherein the luminescent material is manganese-doped zinc sulfide ZnS:Mn or terbium-doped zinc sulfide ZnS:Tb.
8. The electroluminescent display element of claim 1 , wherein the layer structure is formed on a glass substrate having a thickness of less than or equal to 400 μm.
9. The electroluminescent display element of claim 1 , wherein the display element is transparent.
10. A method for manufacturing an inorganic thin film electroluminescent display element, the method comprising forming a layer structure as defined in claim 1 .
11. The method of claim 10 , wherein the first and the second dielectric layers are formed by atomic layer deposition.
12. The method of claim 11 , wherein the hafnium oxide sub-layers are formed using tris(dimethylamino)cyclopentadienylhafnium CpHf(NMe 2 ) 3 as a precursor for hafnium.
13. The method of claim 10 , wherein the luminescent layer is formed by atomic layer deposition using a maximum process temperature in a range of 125 to 300° C.