OLED device with improved high temperature operation
View Patent ↗A method of making an OLED device includes providing an anode and a spaced cathode, and a hole-transporting layer provided between the anode and cathode, such hole-transporting layer including a first hole-transporting material having a first glass transition temperature Tg 1 . The method further includes providing a first light-emitting layer including as a main component, a second hole-transporting material having a second glass transition temperature Tg 2 , such light-emitting layer disposed between the hole transporting layer and the cathode and in contact with the hole-transporting layer, and wherein Tg 1 is greater than Tg 2.
1. A broadband-emitting OLED device comprising:
a) an anode and a spaced cathode
b) a hole-transporting layer provided between the anode and cathode, such hole-transporting layer including as a main component a first hole-transporting material which is selected from arylamine derivatives having a first glass transition temperature Tg1;
c) a first light-emitting layer including as a main component 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB) having a second glass transition temperature Tg2, such light-emitting layer disposed between the hole transporting layer and the cathode and in contact with the hole-transporting layer, and wherein Tg1 is greater than Tg2; and
d) a second light-emitting layer disposed between the first light-emitting layer and the cathode; and
wherein the first light-emitting layer emits light having a hue in a range of yellow to red, and the second light-emitting layer emits light having a hue in a range from blue to green.
2. The broadband-emitting OLED of claim 1 wherein the first light-emitting layer further includes an anthracene derivative and a light-emitting dopant, such anthracene derivative provided in an amount that is less than NPB by volume.
3. The broadband-emitting OLED of claim 2 wherein the second light-emitting layer includes NPB in an amount of greater than 0% and less than 15% by volume.
4. The broadband-emitting OLED device of claim 1 further including a hole-injecting layer in contact with the hole-transporting layer and the anode.
5. The broadband-emitting OLED device of claim 1 wherein the first hole transporting material includes TNB, iso-TNB derivatives, spiro-TAD, or spiro-NPB.
6. The broadband-emitting OLED device of claim 1 wherein the first hole transporting material includes TNB.
7. The broadband-emitting OLED device of claim 4 wherein the hole injecting layer includes a fluorocarbon compound, hexaazatriphenylene derivatives, porphyrinic compounds, m-MTDATA (4,4′,4″-tris[(3-methylphenyl) phenyl-amino]triphenylamine), or inorganic oxides including vanadium oxide (VOx), molybdenum oxide (MoOx), nickel oxide (NiOx) or tungsten oxide (WOx).
8. The broadband-emitting OLED device of claim 1 wherein the thickness of the hole-transporting layer is in a range of 5 nm-260 nm.
9. The broadband-emitting OLED device of claim 1 wherein the thickness of the hole-transporting layer is in a range of 5 nm-40 nm.