Photolithographic patterning of organic electronic devices
A method of making an OLED device includes providing a first undercut lift-off structure over the device substrate having a first array of bottom electrodes. Next, one or more first organic EL medium layers including at least a first light-emitting layer are deposited over the first undercut lift-off structure and over the first array of bottom electrodes. The first undercut lift-off structure and overlying first organic EL medium layer(s) are removed by treatment with a first lift-off agent comprising a fluorinated solvent to form a first intermediate structure. The process is repeated using a second undercut lift-off structure to deposit one or more second organic EL medium layers over a second array of bottom electrodes. After removal of the second undercut lift-off structure, a common top electrode is provided in electrical contact with the first and second organic EL medium layers.
1. A method of making an OLED device comprising:
a) providing a device substrate having a first array of bottom electrodes, a second array of bottom electrodes and a third array of bottom electrodes;
b) depositing third organic EL medium layers over the device substrate including over the first, second and third arrays of bottom electrodes, wherein the third organic EL medium layers include at least a third light-emitting layer;
c) providing over the third organic EL medium layers a first undercut lift-off structure having a first pattern of openings corresponding to the first array of bottom electrodes;
d) using the first undercut lift-off structure as an etch mask and removing by dry etching the third organic EL medium layers from areas over the first array of bottom electrodes;
e) depositing first organic EL medium layers including at least a first light-emitting layer over the first undercut lift-off structure and over the first array of bottom electrodes;
f) removing the first undercut lift-off structure and overlying first organic EL medium layers by treatment with a lift-off agent comprising a fluorinated solvent to form a first intermediate structure;
g) providing over the first intermediate structure a second undercut lift-off structure having a second pattern of openings corresponding to the second array of bottom electrodes;
h) using the second undercut lift-off structure as an etch mask and removing by dry etching the third organic EL medium layers from areas over the second array of bottom electrodes;
i) depositing second organic EL medium layers including at least a second light-emitting layer over the second undercut lift-off structure and over the second array of bottom electrodes;
j) removing the second undercut lift-off structure and overlying second organic EL medium layers by treatment with a lift-off agent comprising a fluorinated solvent to form a second intermediate structure; and
k) depositing a common top electrode over the second intermediate structure in electrical contact with the first, second and third organic EL medium layers.
2. The method of claim 1 , wherein at least one undercut lift-off structure comprises two patterned layers including a fluorinated material base layer and an overlying photoresist layer wherein the fluorinated material base layer is undercut relative to the photoresist layer.
3. The method of claim 1 , wherein at least one undercut lift-off structure comprises a patterned fluorinated photoresist developed using a fluorinated solvent and having an undercut profile.
4. The method of claim 1 , wherein at least one undercut lift-off structure comprises two patterned layers including a fluorinated material base layer and an overlying fluorinated photoresist layer, the overlying fluorinated photoresist layer provided from a photoresist composition comprising a fluorinated coating solvent.
5. The method of claim 4 , wherein the fluorinated material base layer comprises a cyclic perfluorinated polymer and the fluorinated coating solvent comprises a hydrofluoroether.
6. The method of claim 1 , further comprising cleaning the second intermediate structure of residual fluorinated material prior to depositing the common top electrode, wherein the cleaning comprises contact with a cleaning agent having a chemical composition different from the lift-off agent, the cleaning agent comprising a fluorinated solvent.
7. The method of claim 1 , wherein the third organic EL medium layers do not include substantial amounts of metal-containing materials.
8. The method of claim 1 , wherein the bottom electrodes act as cathodes and the common top electrode acts as a respective anode.
9. The method of claim 1 , further comprising depositing one or more common organic EL medium layers over the second intermediate structure prior to depositing the common top electrode.