Multilayer device and method of making
View Patent ↗The invention relates to composite articles comprising a substrate and additional layers on the substrate. According to one example, the layers are selected so that the difference in the coefficient of thermal expansion (CTE) between the substrate and a first layer on one side of the substrate is substantially equal to the CTE difference between the substrate and a second layer on the other side of the substrate. The stress caused by the CTE difference and/or shrinkage on one side of the substrate during heating or cooling is balanced by the stress caused by the CTE difference on the other side of the substrate during heating or cooling. Such stress balancing can reduce or minimize curling of the substrate.
1. An article comprising:
a polymeric substrate having a first side and a second side;
a first layer on the first side of the polymeric substrate, the first layer having a first coefficient of thermal expansion (CTE);
a second layer on the second side of the polymeric substrate;
a third layer on the second layer, the third layer comprising a transparent conductor; and
a fourth layer on the third layer, the fourth layer comprising an organic semiconductor layer;
wherein the second layer has a second CTE which is substantially equal to the first CTE.
2. The article of claim 1 , wherein the fourth layer comprises an organic electroluminescent layer.
3. The article of claim 1 , wherein the fourth layer comprises an organic photovoltaic layer.
4. The article of claim 1 , wherein said transparent conductor comprises a metal or a conducting oxide.
5. The article of claim 1 , wherein the transparent conductor comprises indium tin oxide.
6. The article of claim 1 , wherein the polymeric substrate comprises polycarbonate.
7. The article of claim 1 , wherein the polymeric substrate comprises at least one of: polyethyleneterephthalate, polyacrylate, silicone, epoxy resin, silicone-functionalized epoxy resin, polyester, polyimide, polyetherimide, polyethersulfone, polyethylenenapthalene, polynorbonene, and poly(cyclic olefin).
8. The article of claim 1 , wherein the polymeric substrate comprises at least one of: polyethyleneterephthalate, polyethelenenapthalene, polynorbonene, and poly(cyclic olefins).
9. The article of claim 1 wherein the polymeric substrate comprises a polycarbonate with a 1,3-bis(4-hydroxyphenyl)menthane repeat unit, the first and second layers comprise SiNx, and the third layer comprises indium tin oxide.
10. The article of claim 1 , wherein the first and second layers each comprise at least one of: a metal nitride, a metal oxide, and a metal oxy-nitride.
11. The article of claim 1 , wherein the first and second layers comprise the same material.
12. The article of claim 1 , wherein at least one of the first layer and the second layer comprises a gas/moisture barrier coating which causes a transmission rate of oxygen through the substrate of less than about 0.1 cm 3 /(m 2 day) as measured at 25 degrees C. and with a gas containing 21 volume-percent oxygen, and a transmission rate of water vapor through the substrate of less than about 1 g/(m 2 day) as measured at 25 degrees C. and with a gas having 100-percent relative humidity.
13. The article of claim 1 , wherein the article forms part of an electronic device.