Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K71/00—Manufacture or treatment specially adapted for the organic devices covered by this subclass
  • H10K71/30—Doping active layers, e.g. electron transporting layers
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B33/00—Electroluminescent light sources
  • H05B33/12—Light sources with substantially two-dimensional radiating surfaces
  • H05B33/14—Light sources with substantially two-dimensional radiating surfaces characterised by the chemical or physical composition or the arrangement of the electroluminescent material, or by the simultaneous addition of the electroluminescent material in or onto the light source
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K50/00—Organic light-emitting devices
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K50/00—Organic light-emitting devices
  • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
  • H10K50/11—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers
  • H10K50/125—OLEDs or polymer light-emitting diodes [PLED] characterised by the electroluminescent [EL] layers specially adapted for multicolour light emission, e.g. for emitting white light
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K71/00—Manufacture or treatment specially adapted for the organic devices covered by this subclass
  • H10K71/10—Deposition of organic active material
  • H10K71/12—Deposition of organic active material using liquid deposition, e.g. spin coating
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
  • H10K85/10—Organic polymers or oligomers
  • H10K85/141—Organic polymers or oligomers comprising aliphatic or olefinic chains, e.g. poly N-vinylcarbazol, PVC or PTFE
  • H10K85/146—Organic polymers or oligomers comprising aliphatic or olefinic chains, e.g. poly N-vinylcarbazol, PVC or PTFE poly N-vinylcarbazol; Derivatives thereof
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
  • H10K85/60—Organic compounds having low molecular weight

Definitions

• the present invention relates to methods of making semiconductor devices using light emitting organic materials, and more specifically, to methods which involve the modification of the properties of an organic film after it has been deposited by either: (i) adding new components into the film from a top or bottom surface; or (ii) by causing .components to leave the film from a top or bottom surface.
• Organic films are typically deposited in thin film form for electrical and optoelectronic applications by uniformly coating a surface by spin-coating or other methods. Sometimes the final organic film itself is not directly formed, but a precursor is deposited which is converted to a polymer by a subsequent step, such as heating or exposure to UV light (e.g. PPV). It is also well known that adding various elements to the organic film can change its electrical and/or optical properties. These may include elements to change the conduction of electrical carriers (e.g. PBD for electron transportability), or dye centers to change the color of photo- and electro-luminescence (e.g.
• the deposited blanket film must be typically etched into a pattern, as might be done by photolithography followed by etching. Then, this process has to be repeated for multiple layers to achieve full color (red, green and blue emitters).
• Etching of organic films and photoresist processing for lithography on organic films has proven to be technically very difficult and expensive. Therefore, instead of making a blanket film of one color, etching and making a blanket film of another color, it would be beneficial to make one blanket film and later locally change the properties of the film to emit different light colors. Thus, the need for etching would be removed.
• An object of the- present invention is to provide a method for manufacturing optoelectronic organic films having locally modified areas. Another object of the present invention is to provide an organic film with various regions of modified optoelectronic properties.
• Still another object and advantage of the invention is to form an organic film with modified properties by applying dopants in desired places.
• a further object and advantage of the invention is the provision of a method for forming an organic film with local modified areas by adding impurities to or removing impurities from the film.
• Even another object of the invention is to provide a method for locally modifying properties of an organic film without the need for photolithography and etching of the organic film.
• a still further object and advantage of the invention is the provision of a method for manufacturing • a locally modified organic film with the need for contacting the surface of said film with solvents.
• an additional object of the invention is to provide a process of forming a locally modified organic film wherein dopant is added to the film in an annealing process.
• Yet an additional object of the present invention is to provide a process for transferring a dopant from one layer to another layer.
• a further object of this invention is the provision of a process for transferring a dopant from one layer to another layer in a desired pattern.
• the methods of this invention involve modification of the properties of an organic film after it has been deposited by either adding new components into it from its top or bottom surface, or by causing components to leave the film from its top or bottom surface.
• the emitting color of light-emitting diodes are . modified based on doped polymers by locally introducing dopants causing different color emission into the film by local application of a solution containing the desired dopant to the film surface (by ink jet printing, screen printing, local droplet application, etc.).
• dopants may be introduced in an organic film by diffusion from one layer into the film in local regions or by locally applying them directly into the organic film.
• dopants may be selectively removed from a film with solvents, etc.
• the active components are incorporated into the polymer when the polymer film is first formed, for example by spin coating it over a surface.
• the properties of the material are modified after a solid film has been formed by later introducing new species into the film from either its top or bottom surface, or removing impurities out through the top or bottom surface especially in a patterned arrangement.
• the method is especially attractive for the local modification of the photoluminescence and/or electro luminesence color of a thin film of the material, for example to create red, green, and blue light-emitting regions after a surface has been coated with a thin film of the material which is the same everywhere.
• FIGS, la and lb are diagrams of the application of dye on top of PVK film.
• FIGS. 2a and 2b are diagrams of dye on PVK film under UV illumination.
• FIG. 3 is a plot of photoluminescence of materials used in FIGS. 1-2.
• FIG. 4a is a diagram of a device and FIG. 4b is a plot of the electroluminsence spectra of PVK and C6.
• FIGS. 5a and 5b are diagrams of removal of local dye with acetone.
• FIG. 6a is a diagram of a device and FIGS. 6b and 6c photographs of the device of FIG. 6a under UV illumination.
• FIG. 7 is a photograph under UN illumination of a device fabricated with an ink jet printer
• FIG. 8a is an experiment showing the effects of temperature on devices fabricated in accordance with the invention, and FIG. 8b is plot thereof.
• FIG. 9 is a photograph under UN illumination of a device formed in accordance with the invention at increasing temperatures.
• FIGS. 10a - 10c illustrate the steps in introducing film dopants from the top.
• FIGS. 11a - lie illustrate the steps in introducing dopants from the bottom.
• FIGS. 12a -12c illustrates the steps for spatially modifying properties of polymer film.
• FIGS. 13a - 13b illustrate the spectra of PNK and PNK with C6.
• FIGS. 14a - 14c illustrate the steps in removing dopant from a polymer film into the underlying layer.
• FIGS. 15a - 15c illustrate the steps in forming patterned addition of dopant from the top.
• FIGS. 16a - 16c illustrate the steps in fabrication of patterned OLEDs.
• FIGS. 17a - 17d illustrate the steps in fabrication of a passive matrix.
• FIGS. 18a - 18c illustrate the steps in removal of dopant from polymer film in a pattern to the underlying layer.
• FIGS. 19a - 19b illustrate the steps in removal of dopant from the top of a film.
• FIGS. 20a - 20c illustrate the steps in the patterned removal of dopant from the top of a film.
• FIGS. 21a - 21d illustrate the steps in fabrication of an active matrix OLED display.
• OLEDs organic light emitting diodes
• the difficulty with using this technology is that the current deposition techniques, such as spin-coating and evaporation, deposit blanket films.
• the film can be used to make devices of a single color.
• the deposited blanket film must be typically etched into a pattern, as might be done by photolithography followed by etching. Then, this process has to be repeated for multiple layers to achieve full color (red, green and blue emitters).
• Etching of organic films and photoresist processing for lithography on organic films has proven to be technically very difficult and expensive. Therefore, instead of making a blanket film of one color, etching and making a blanket film of another color, it would be beneficial to make one blanket film and later locally change the properties of the film to emit different light colors. Thus, the need for etching would be removed.
• the present invention in a broad, general sense, relates to the application of an organic film and thereafter modifying local characteristics thereof by adding or removing components, i.e. dopants, dies, etc., to or from the film to change the local characteristics of the film.
• the invention relates to modifying the optoelectronic properties of an organic film by impurity or additional removal in a patterned fashion after application of the film.
• the invention relates to modifying the emitting color of light-emitting diodes based on doped polymers by locally introducing dopants causing different color emission into an organic film by local application of solutions containing desired dopants to the film surface, i.e. by ink-jetting or screen printing.
• impurities contained within the film prior to application can be removing therefrom in desired patterns through various methods such as by the application of solvents.
• PVK poly(9-vinylcabazole)
• TCE acetone or trichloroethylene
• metal cathodes could be patterned on top of the locally dyed regions, thus achieving full color integration.
• FIG. 2a shows a picture of these drops taken from above with a UV lamp shining on them to excite fluorescence of the organic film. Under UV, they appear to be a greenish yellow color. These droplets were also placed onto glass where no diffusion occurs and the C ⁇ .remains on the surface, and the solvents were allowed to evaporate, as shown in FIG. 2b. Under UV lamp they appear to be a reddish color.
• FIG. 3 shows the PL spectra of a pure PVK film (peak at 410 nm ), a PVK film locally dyed with C6 (peak at 490 ran), a blend film, where the PVK was dyed in solution with C6 (peak a 490 nm), and the dye on glass (peak at 580 nm).
• FIG. 4 a shows the device structure
• FIG. 4b shows the electro- luminescence (EL) spectrum of the device and the EL of a blend device made by dissolving PVK and C6 in chloroform, spinning the film, and evaporating contacts.
• PVK dissolved in chloroform was spun onto glass coated with indium tin oxide (ITO, a transparent conductor).
• ITO indium tin oxide
• C6 dissolved in acetone was dropped onto the surface, the sample was then spun again.
• a metal contact was evaporated on top of the dyed area.
• the EL spectra of the locally dyed device is seen to have the same 490 nm peak as the blend device Therefore, this shows that the dye not only interacts with the PVK, but it interacts in such a way that a device can be made which has a similar EL spectra to blend device.
• FIG. 5a and 5b shows a schematic of the experiment.
• PVK and C6 were dissolved in chloroform. Next, they were spun-on to an
• FIG. 6a shows a schematic of the device made on the washed film.
• the film was prepared as mentioned above, and then metal cathodes were evaporated in the washed areas and in the non-washed areas.
• FIGS. 6b and 6c are pictures of the devices, from below, emitting light.
• FIG. 6b shows a device emitting green (appears light blue because of camera used) and
• FIG. 6c shows an emitting blue.
• the green device is emitting green because the metal cathode was evaporated on top of the dyed film, and the blue device is emitting blue, because the metal cathode was evaporated on top of the washed film.
• FIG. 7 shows a picture of a piece of glass coated with ITO, onto this glass was spun a 1000 angstrom thick film of PVK. Then an Epson Stylus Color 400 ink-jet printer was used to pattern C6 dissolved in acetone on top of the film. The sample was then illuminated under UV. This shows that the dyes can be patterned by an ink-jet printer with a spot diameter of -500 ⁇ m. The next step is to try to determine the ultimate resolution of this technique. An experiment was done to determine if the diameter of the printed spots could be influenced by temperature.
• FIG. 7 shows a picture of a piece of glass coated with ITO, onto this glass was spun a 1000 angstrom thick film of PVK. Then an Epson Stylus Color 400 ink-jet printer was used to pattern C6 dissolved in acetone on top of the film. The sample was then illuminated under UV. This shows that the dyes can be patterned by an ink-jet printer with a spot diameter of -500 ⁇ m. The next
• FIG. 8a shows the experimental set-up, a 1000 angstrom film of PVK was spun onto a piece of glass coated with ITO. The sample was then placed onto a hot plate. Droplets of equal volume of C6 dissolved in acetone and equal volumes of C6 dissolved in TCE were dropped on to the PVK film at different temperatures. It was observed that at higher temperatures the spots did not spread as far and therefore had smaller diameters. This is shown in the plot of FIG. 8b. This could potentially make the spot size -0.6 times smaller. However, this data does not reveal the difference observed in using TCE and acetone.
• FIG. 9 shows a picture of the same spots dropped onto the PVK film at increasing temperatures lit up by a UV lamp. What can be seen is that there are, at higher temperatures in the TCE drops, bright yellow spots which are - 1/3 of the outer spot, and have a more intense luminescence. This may be because, as the solvent dries the C6 tends to stay in the solution and what is left at the end is a highly concentrated small diameter spot.
• this spot profile is checked using a surface profilometer it is seen that the dye is actually sitting on the surface. Therefore, in order to take advantage of this small diameter, the substrate would have to be heated further, to allow the dye to thermally diffuse into the film.
• PVK can be locally dyed by dissolving dye in acetone or TCE and dropping it on to the surface. Also, this dyed area can be made into a device.
• a blend film of PVK and C6 can have the C6 locally washed out of it using acetone, and a device can be made using this technique.
• ink-jet printed dyed lines can be made with widths of -500 ⁇ m. This width can be further reduced by printing with TCE onto a heated substrate to obtain a spot 1/10 of the diameter of a spot made at room temperature. This substrate would have to then be heated again to thermally diffuse the dye into the film.
• FIGS. lOa-lOc illustrate the basic method for introducing film dopants from the top in the fabrication of red, green and blue OLED devices on a common substrate.
• a uniform film of polymer 10 without the desired dopant is formed on substrate 11.
• the polymer film 10 may contain other dopants.
• dopant 12 is placed on the surface of the polymer film 10 by evaporation, spin coating, or other method.
• annealing or other process caused the dopant 12 to enter the film 10 by diffusion or by other methods.
• the solvents used in spin coating the dopant 12 on the surface may cause dopant 12 to enter polymer 10 and be deposited into it without need for the steps described in FIG. 10c. In this case there is never a solid dopant layer on the surface.
• FIGS, lla-llc show the introduction of dopants into a film from the bottom thereof.
• a substrate 13 has a coating 14 put down thereon.
• the coating 14 may contain the desired dopant or, the dopant may be applied in the manner described in FIGS. lOa-lOc (i.e. may be polyanaline or similar hole transport layer in OLED).
• the polymer film 15 is deposited onto the coating 14.
• annealing causes dopant to partially migrate from layer 14 into polymer film 15.
• the solvents used in spin coating the top polymer may "leach" dopant out of the underlying layer without the need for the thermal cycling described in FIG. lie.
• FIGS. 12a-12c show the steps of a method for spatially modifying the properties of the polymer film.
• FIG. 12a illustrates the deposition of a polymer 16 onto a substrate 17 in the same manner as discussed in connection with FIG. 10a.
• FIG. 12b shows the creation of local regions of different dopants, 18 and 19 on the polymer surface 16 by local deposition methods such as evaporation through different shadow masks, deposition by screen printing using different screens, or by ink jet printing, or other printing processes using different patterns for each dopant.
• FIG. 12c illustrates the heat treatment of the structures of FIG. 12b by annealing, for example, to cause the dopant 18 and 19 to migrate into the polymer 16.
• solvents used in screen printing or in ink jet printing may carry dopants directly into the polymer so that the heat treatment step of FIG. 12c may not be required.
• both the photoluminescence (FIG. 13a) and electroluminesence (FIG. 13b) show the shift between pure PNK film and doped PVK.
• the dopant need not be pure dopant, but may be co-deposited with another material. Subsequent process (or the very deposition process itself) can then cause dopant to move into underlying layer. Other material may be removed or remove itself (evaporate), or stay behind as separate layer and be part of final structure doped or undoped.
• FIGS. 12a-12c may be applied to the method described in connection with FIGS, lla-llc so that patterns of dopant may be introduced into underlying material before top polymer film is deposited.
• FIGS. 14a-14c illustrate the steps in the removal of dopant from polymer film into an underlying layer.
• substrate 19 has a bottom absorber film layer 20 deposited thereon.
• the absorber layer has a low chemical potential for the desired dopant.
• the doped polymer 21 is deposited onto the absorber layer 20.
• annealing or another cycle which causes the dopant to move is applied.
• a solvent may be applied which infiltrates (from the top) both the polymer layer 21 and the bottom layer 20 to enable the dopant in the top polymer layer to migrate into the bottom layer 20.
• FIGS. 15a-15c shown the patterned addition of dopant from the top with an impermeable barrier.
• the undoped polymer 23 is deposited on substrate 22.
• FIG. 15c dopant 27 in ambient is heat treated by annealing.
• the structure of FIG. 15b may be placed into a solvent containing the dopant
• FIGS. 16a-16c illustrate the application of the method described in FIG. 12 to the formation of patterned OLEDs of different colors. As shown in FIG.
• undoped polymer 30 is deposited everywhere onto ITO layer 29 on glass substrate 28.
• the ITO may be patterned.
• Local red (31), green (32) and blue (33) regions are formed by locally doping the polymer 30. These red, green and blue regions may be formed by ink jet printing three different solutions in different regions. Heat treating may then be applied.
• top contacts In FIG. 16c, top contacts
• FIGS. 17a-17d illustrate the application of the method described in FIG.
• FIG. 17a ITO lines 37 are formed in one direction on glass substrate 38.
• FIG. 17b a uniform polymer film 39 is applied over the ITO lines.
• red, green, blue doped polymer 40 is formed on the ITO lines in the polymer film as by the steps described in FIG. 16b.
• FIG. 17d cathode lines 41 as top contacts perpendicular to the bottom contact lines 37. Doping need only be in the region of the intersection of the top and bottom contact lines.
• FIGS. 18a-18c illustrate the removal of dopant from polymer film in a pattern to the underlying layer.
• the absorber film 43 is deposited onto substrate 42.
• absorber film 43 is patterned or coated with a patterned impervious layer 44.
• Doped polymer 45 is added onto the layer 44.
• FIG. 18c shows the effect of annealing or other treatment of the structure of FIG. 18b in causing the doping to move into the underlying layer 43, where it is not impeded by the impervious barrier. The movement of the dopant may be accomplished through the use of a solvent as discussed in connection with FIG. 14c.
• FIGS. 19a-19b shows the removal of dopant from the top of an unpatterned film. In FIG.
• FIG. 19a doped film 47 is deposited onto a substrate 46 as by spin coating with dopant in solution.
• FIG. 19b illustrates the treatment of the structure of FIG. 19a by annealing in certain ambients or washing with solvent to the cause the reduction of dopant in layer 47. Washing by applying the drop may not remove the dopant from the film, but cause it to move to the edge of the drop location, leaving little dopant in the center of the drop.
• FIGS. 20a-20c illustrate the patterned removal of dopant from the top of the film.
• doped polymer film 49 is deposited onto substrate 48.
• patterned impermeable layer 50 is applied over the doped polymer layer 49.
• annealing the structure of FIG. 20b causes dopant to evaporate in areas without barrier 50. This evaporation may also be accomplished by washing with solvent to remove dopant in the areas without barrier 50, or treating with a solvent vapor.
• FIGS. 21a-21d show the formation of an active matrix OLED display.
• glass substrate 51 has patterned insulator 52 and electrodes 53 formed thereon. The electrodes are connect to transistors (not shown) in the pixels.
• undoped organic layer 54 is deposited everywhere on the structure of FIG. 21a.
• red (55), green (56) and blue (57) dopant is applied as by ink jet printing.
• top electrode 58 is applied without a pattern. Top electrode 58 may be, for example Al:Li or Mg:Ag cathode.
• Solvent methods may cause problems with small organic molecule based films, however, dopants could be deposited by diffusion by thermal treatment by other localized methods such as evaporation through a mask, etc.
• undoped means not doped with the dopant being added or removed. Other dopants may be present.

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  • 1999-04-12 AU AU36399/99A patent/AU3639999A/en not_active Abandoned
  • 1999-04-12 EP EP99918499A patent/EP1101244A4/de not_active Withdrawn
  • 1999-04-12 WO PCT/US1999/007970 patent/WO1999053529A2/en not_active Application Discontinuation
  • 1999-04-12 JP JP2000543997A patent/JP2002511637A/ja active Pending
  • 1999-04-12 KR KR1020007011393A patent/KR20010042689A/ko not_active Application Discontinuation

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