Method for reducing the surface roughness of a thin layer of conductive oxides
A method for reducing the surface roughness of thin layers of conductive oxides for thin-layer opto-electronic devices envisages polishing with a finishing cloth and an abrasive compound, which has a basic pH and contains silica particles.
1 . A method for reducing the surface roughness of a thin layer for thin-layer opto-electronic devices, the thin layer comprising at least one conductive oxide and having a thickness of between 20 nm and 1000 nm, the method being characterized in that it comprises a polishing step of a mechanical type for polishing a surface of the thin layer using a polishing cloth and an abrasive compound, which includes particles having a diameter of between 5 nm and 150nm.
2 . The method according to claim 1 , in which said particles present substantially anti-aggregating properties.
3 . The method according to claim 1 , in which said particles are designed to exert an electrostatic repulsion on one another.
4 . The method according to claim 1 , in which said particles are silica particles and said compound has a basic pH, polishing being of a mechanical and chemical type.
5 . The method according to claim 1 , in which said polishing cloth is a woven cloth.
6 . The method according to claim 1 , in which said cloth is made to rotate on said surface at a speed of between 400 r.p.m. and 600 r.p.m. applying a pressure of between 0.3 kg/cm 2 and 0.8 kg/cm 2 for between 10 seconds and 20 seconds.
7 . The method according to claim 1 , in which the polishing cloth is chosen in the group consisting of:
semifinishing cloths,
finishing cloths, and
super-finishing cloths.
8 . A thin layer for opto-electronic devices, the layer comprising at least one conductive oxide and being characterized in that it presents a difference in height between peak and trough of less than 28 nm and in that it has a thickness of between 20 nm and 1000 nm.
9 . The layer according to claim 8 , and presenting a difference in height between peak and trough of less than 22 nm.
10 . The layer according to claim 8 , and presenting a difference in height between peak and trough of less than 15 nm.
11 . The layer according to claim 8 , and presenting a difference in height between peak and trough of less than 12 nm.
12 . The layer according to claim 8 , and presenting a difference in height between peak and trough of less than 8 nm.
13 . The layer according to claim 8 , and having a mean roughness of less than 1.7 nmn.
14 . The layer according to claim 8 , and having a mean roughness of less than 1.0 nm.
15 . The layer according to claim 8 , and having a thickness of between 20 nm and 300 nm.
16 . A thin-layer opto-electronic device comprising at least one optically active intermediate layer ( 4 , 5 ); and a thin layer ( 2 ), which comprises at least one conductive oxide and is set in contact of the optically active intermediate layer ( 4 , 5 ), the device being characterized in that the thin layer ( 2 ) is a thin layer according to claim 8 .
17 . The device according to claim 16 , in which the optically active intermediate layer ( 4 , 5 ) has a thickness of between 1 nm and 300 nm.
18 . An organic electroluminescent device (OLED) comprising at least one cathode ( 3 ), at least one anode ( 2 ) and at least one optically active intermediate layer ( 4 , 5 ) set between the anode and the cathode, said optically active intermediate layer ( 4 , 5 ) comprising at least one organic material, the device ( 1 ) being characterized in that said anode ( 2 ) includes a thin layer according to claim 8 .
19 . The device according to claim 18 , in which the optically active intermediate layer ( 4 , 5 ) has a thickness of between 1 nm and 300 nm.