KR20010042689A - Modification of polymer optoelectronic properties after film formation impurity addition or removal - Google Patents

Abstract

The process of the present invention involves modifying the properties of an organic film by adding new components to or removing components from the top or bottom surface of the film after film formation. For example, by applying a necessary dopant-containing solution to the film surface (inkjet printing, screen printing, local droplet application), a dopant that emits different colors locally is introduced into the film to produce a light emitting diode based on the doped film. It is denatured. This is due to the direct patterning of three separately formed organic layers (evenly coating the entire surface upon each formation) in areas of R, G and B devices that are distinguished due to the sensitivity of the organic materials to the chemicals used in conventional patterning techniques. Overcome the difficulties involved Alternatively, a dopant can be introduced into the organic film by diffusion from the layer to the film. The dopant may also be selectively removed from the film using a solvent.

Description

Modified method for polymer photoelectricity after addition or removal of film forming impurity {MODIFICATION OF POLYMER OPTOELECTRONIC PROPERTIES AFTER FILM FORMATION IMPURITY ADDITION OR REMOVAL}

Blends and polymers of polymers with small organic molecules are first widely used in the manufacture of organic light emitting diodes and thin film transistors.

The organic film is precipitated in the form of a thin film in the electric and photoelectric fields by uniformly coating the surface by a method such as stain coating. Occasionally, the final organic film is not directly formed, but the precursor is converted into a polymer by a subsequent step such as heating or UV light exposure (PPV). It is also well known that the addition of various elements to the organic film can change the electrical or optical properties. Examples include elements that change the conductivity of an electrical carrier (eg electron moving PBDs) or dye centers that change the color of photo- and electro-luminescing (eg PVK edin coumarin 6). These additional elements are usually added to the original material before final film precipitation. These various groups may be bound to the polymer chains or added as polymers or individual small molecules to the polymer containing solution prior to thin film formation, for example, before the polymer is precipitated by spin coating. In either case, all materials in the initial solution become part of the final film.

True color flat panel displays are achieved using organic light emitting diodes (OLEDs). The difficulty with using this technique is that the first precipitation techniques, such as spin-coating and evaporation, precipitate the blanket film. This film can be used to make monochrome devices. The precipitated blanket film must be patterned by etching and photolithography to achieve individual emitters of different colors adjacent to each other such as red, green and blue. This process is repeated in order for the multilayer to achieve true colors (red, green and blue emitters). Photoetching is technically very difficult and expensive for etching of organic films and lithography on organic films. Therefore, instead of forming a blanket film of one color and forming a blanket film of another color, it would be beneficial to produce one blanket film and locally change the properties of the film to emit different colors. Thus, the need for etching is eliminated.

Another method is inkjet printing of localized areas but a problem associated with inkjet printing is that printed dots do not have a uniform thickness.

Therefore, what is needed is a method of modifying the properties of the film by introducing or removing impurities after film formation.

Summary and purpose of the invention

It is an object of the present invention to provide a method for producing a photovoltaic organic film having locally modified regions.

It is another object of the present invention to provide various modified photovoltaic regions in the organic film.

Another object of the present invention is to form an organic film having modified properties by applying a dopant in the required place.

Another object of the present invention is to provide an organic film forming method having locally modified regions by adding or removing impurities.

Another object is to provide a method of locally modifying the properties of an organic film without the need for photolithography and etching of the organic film.

Another object is to provide a method of making a locally modified organic film for the purpose of contacting the film surface with a solvent.

Another object is to provide a process for transferring the dopant from one layer to another.

Another object is to provide a process for transferring the dopant from one layer to another in the required pattern.

The method of the present invention is to modify the properties of the organic film by adding new components to the top or bottom surface of the film or removing the components from the film top or bottom surface after organic film precipitation. For example, based on the doped film by applying a solution containing a dopant that requires the emission color of the light emitting diode to the film surface (inkjet printing, screen printing, local droplet application) and introducing a dopant that emits different colors to the film. It is denatured. This overcomes the difficulties encountered when directly patterning three separate formed organic layers, each of which uniformly coats the entire surface, due to the sensitivity of the organic material to the chemicals typically used in traditional patterning techniques. Alternatively, the dopant may be introduced into the organic film by diffusing from one layer to a localized area of the film or by directly applying the dopant to the organic film. Alternatively, the dopant can be selectively removed from the film using a solvent.

As a rule, all active ingredients are introduced into the polymer upon initial formation of the polymer film, such as by spin coating onto the surface. In the present invention, after the solid film is formed, the properties of the material are modified by introducing new species into the film top or bottom surface or by removing it in a patterned arrangement from the top or bottom surface. The method is particularly useful for locally modifying the photo- or electroluminescent color of a thin material film to produce red, green and blue light emitting regions after the surface is coated with a thin material film.

The present invention relates to a method for manufacturing a semiconductor device using a luminescent organic material, in particular (i) the properties of an organic film after film precipitation by adding new components to or removing components from the top or bottom surface of the film. It relates to a method comprising the step of denaturing.

1a and 1b show the dye applied on top of the PVK film.

2a and 2b show dyes on PVK films under UV illumination.

3 is a light-emitting graph of the material used in FIGS. 1-2.

4A is a diagram of the device and FIG. 4B is an electroluminescence spectral graph of PVK and C6.

5a is a diagram in which 5b is acetone to remove the local dye.

7 is a photograph under UV illumination of a device made with an inkjet printing machine.

8A is an experiment showing the effect of temperature on a device made according to the invention and FIG. 8B is a graph thereof.

9 is a photograph under UV illumination of a device manufactured according to the invention (with increasing temperature).

10A-10C show the step of introducing a film dopant from the top.

11A-10C show the step of introducing a film dopant from the bottom.

12A-12C show the steps of modifying the properties of the polymer film.

13A-13B show spectra of PVK and C6 containing PVK.

14A-14C show the step of removing the dopant from the polymer film to the underlying layer.

15A-15C show adding a patterned dopant from the top.

16A-16C show patterned OLED fabrication steps.

17A-17D show passive matrix fabrication steps.

18A-18C show the steps of removing the dopant in a pattern from the polymer film to the underlying layer.

19A-19B show the step of removing the dopant from the top of the film.

20A-20C show the step of patterning removal of the dopant from the top of the film.

21A-21D show the manufacturing steps of an active matrix OLED display.

* Code Description

10 ... polymer film 11 ... substrate

12 ... dopant 13 ... substrate

14 ... Coating 15 ... Polymer Film

16 ... Polymer 17 ... Substrate

18,19 ... dopant 20 ... film layer

21 ... doped polymer 22 ... substrate

23 ... undoped polymer 24,25,26,27 ... dopant

28 ... glass substrate 29 ... ITO layer

30 ... Polymer 31 ... Red Zone

32 ... green zone 33 ... blue zone

34,35,36 ... Top contact 37 ... ITO line

38 ... glass substrate 39 ... polymer film

40 ... doped polymer 41 ... cathode line

42 ... Substrate 43 ... Absorbent Film

44 ... impermeable layer 45 ... doped polymer

46 ... Substrate 47 .. Doped Film

48 ... Substrate 49 ... Doped Polymer Layer

50 ... barrier 51 ... glass substrate

52 ... insulator 53 ... electrode

54 ... undoped organic layer 55 ... color dopant

56 ... green dopant 57 ... blue dopant

58 ... electrode

True color flat panel display manufacturing goals are achieved using organic light emitting diodes (OLEDs). The difficulty with using this technique is that recent precipitation techniques, such as spin-coating and evaporation, precipitate the blanket film. This film can be used to make monochrome devices. The precipitated blanket film must be patterned by photolithography and etching to obtain different color emitters neighboring each other, such as red, green and blue. This process is then repeated for multiple layers to obtain true colors (red, green and blue emitters). Photoresist processing on the etching of organic films and on organic film lithography is technically very difficult and expensive. Therefore, it would be beneficial to manufacture one blanket film and locally modify the properties of the film to emit a variety of colors instead of making a blanket film of one color, etching and producing a blanket film of another color. Thus the need for etching is eliminated.

The present invention relates to the application of organic films and the application of components (ie dopants, dyes) to or removal from the film to modify the local properties of the film. In particular, the present invention relates to denaturing the photoelectric properties of organic films by adding or removing impurities in a patterned manner after film application. In addition, the present invention applies a necessary dopant-containing solution to the surface of the film by inkjet printing or screen printing to locally modify the emission color of the light-emitting diode based on the doped polymer by locally introducing a dopant that emits different colors into the organic film. Related to Alternatively, impurities contained in the film prior to application may be removed in a required pattern through various methods such as solvent application.

One method is to locally dye poly (9-vinylcarbazole) (PVK, hole transfer polymer) spinning films with rust, red and blue dyes. The dye is dissolved in acetone or trichloroethylene (TCE) that does not dissolve PVK and can be patterned on top of the PVK film using an inkjet printer. In FIGS. 1A and 1B the dopant diffuses into the film and the solvent evaporates. The metal cathode is then patterned on top of the locally dyed area to complete true color integration.

Coumarin 6 (C6, green dye) droplets dissolved in TCE and acetone are applied onto a 100 Angstrom thick PVK film using a pipette and the solvent is evaporated. 2A shows an image of droplets captured from above using a UV lamp illuminated to activate the fluorescence of the organic film. Under UV, the droplets appear as a light green color yarn. These droplets are added to the glass phase where no diffusion occurs, C6 remains on the surface, and the solvent evaporates (FIG. 2B). The droplets appear red under UV. This indicates that there is some interaction with the PVK when the droplet is applied on the PVK film. This is because the green color appears when PVK is in the dyed area, and the dye appears red when PVK is not present. The interaction is the diffusion of the dye into PVK.

In order to explain the observations above in a more quantitative manner, photo-luminescent spectra are taken. FIG. 3 shows pure PVK film (peak at 410 nm), PVK film stained locally with C6 (peak at 490 nm), blend film (peak at 490 nm) PVK stained with C6 containing solution, and dye on glass (580 PL spectrum of the peak at nm). This provides evidence that the dye interacts with PVK and the PL spectrum is almost the same as that of the blend film, and thus can be formed in the device. Therefore, the next step is to manufacture the device using a local staining procedure.

4A shows the device structure and FIG. 4B shows the electroluminescence (EL) spectrum of the blend device formed by solving PVK and C6 in chloroform, spinning the film and evaporating the contacts. PVK dissolved in chloroform is spun onto glass coated with indium pole oxide (ITO, transparent conductor) for making locally dyed devices. Next, C6 droplets dissolved in acetone are applied to the surface and the sample is spun again. Finally, the metal contacts evaporate over the dyed area. The EL spectrum of the locally stained device has the same 490 nm peak as the blend device. It can therefore be seen that dyes interact with PVK and devices with EL spectra similar to blend devices can be produced.

To further examine the local staining phenomenon, an experiment is conducted to see if the dye can be washed out of the blended film in solution. 5A and 5B show an overview of the experiment. First PVK and C6 are dissolved in chloroform. They are then spin coated onto a glass substrate to form a 1000 angstrom thick film. The film is green when observed under a UV lamp. A drop of acetone is then applied to the surface. When the UV lamp is shining on the sample, it can be seen that the sample is blue where acetone emission is applied and green where no acetone is applied. This indicates that the dye can be washed away from the blend film to create a dye free local area. Therefore, two different color LEDs can be formed on a locally washed substrate.

6A shows a device formed on a washed film. The film is prepared as above and the metal cathode is evaporated in the non-washed area after the cleaned area. These cathodes are evaporated by heat and patterned by a shadow mask. 6B and 6C are devices that emit light from below. FIG. 6B shows a device emitting green (appearing in light blue due to the camera used) and FIG. 6C shows a device emitting red. The green device emits blue or emits green on top of the dyed film top and the blue device emits blue because the metal cathode evaporates on top of the washed film.

Therefore, the device can be manufactured by locally dyeing the PVK film or by locally washing the dyed PVK film. The next step is to pattern the dye using inkjet printing. FIG. 7 shows an ITO coated glass piece in which a 1000 Angstrom thick PVK film is spin coated onto the glass. An Epson Stylus Color 400 inkjet printer was then used to pattern the C6 dissolved in acetone on top of the film. The sample is irradiated under UV. The dye may be patterned by an inkjet printing machine having a spot diameter of ˜500 μm. The next step is to measure the final resolution of the technique.

An experiment is conducted to determine whether the diameter of the printed spot is affected by temperature. 8A shows an experimental setup where a 1000 Angstrom thick PVK film is spin coated onto an ITO coated glass piece. The sample is then placed on a hot plate. C6 droplets dissolved in the same volume of acetone and C6 droplets dissolved in TCE are applied to the PVK film at different temperatures. At higher temperatures the spots do not spread far and have a smaller diameter. This is shown in the graph of FIG. 8B. Therefore, the spot size can be made ~ 0.6 times smaller. However, this data is no difference when using TCE and acetone.

9 is an image of the same spots applied to PVK films upon increasing temperature under UV lamps. At higher temperatures, bright yellow spots with ˜1 / 3 of the external spots and more intense emission in the TCE droplets are observed. The reason for this is that as the solvent dries, C6 tends to remain in solution and eventually remains a highly concentrated small diameter spot. Examination of the speckle profile with a surface contour gauge shows that the dye is located on the surface. Eventually, in order to take advantage of the small diameter, the substrate must be heated to allow the dye to thermally diffuse into the film.

In conclusion PVK can be dyed locally by dissolving the dye in acetone or TCE and adding it to the surface. Also dyed areas may be formed in the device. The device can be manufactured using this technique because acetone can be used to locally wash away C6 from the blend film of PVK and C6. Eqjet printed dyed lines can be formed to a width of ˜500 μm. The width can be further reduced by printing with TCE on a heated substrate to obtain spots that are one tenth the size of the spot diameters formed at room temperature. The substrate must be heated again to thermally diffuse the dye into the film.

10A-10C show a method of introducing a film dopant on top of fabricating red, green and blue OLED devices on a common substrate. In FIG. 10A, a uniform polymer film 10 without the necessary dopant is formed on the substrate 11. The polymer film 10 may contain other dopants. In FIG. 10B, the dopant 12 is applied to the surface of the polymer film 10 by evaporation and spin coating. The annealing or other process in FIG. 10C causes the dopant 12 to enter the film 10 by diffusion or the like. The solvent used to spin coat the dopant 12 on the surface allows the dopant 12 to enter the film 10 and to precipitate therein without the steps described in FIG. 16C. In this case there is never a solid dopant layer on the surface.

11A-11C show the introduction of the dopant into the film at the bottom. In FIG. 11A substrate 13 has a coating 14. Coating 14 may contain the necessary dopant or may be introduced in the manner disclosed in FIGS. 10A-10C (which may be polyaniline or a similar hole transport layer in an OLED). In FIG. 11B, the polymer film 15 is deposited on the coating 14. Annealing in FIG. 11C partially moves the dopant from layer 14 to polymer film 15. The solvent used to spin coat the top polymer may be “exuded” from the bottom layer without the thermal cycling of FIG. 11C.

12A-12C show the steps of denaturing the properties of the polymer film. FIG. 12A shows that the polymer 16 is precipitated onto the substrate 17 in the same manner as was published in connection with FIG. 10A. 12A shows different dopant 18,19 regions on the polymer surface 16 by evaporation through various shadow masks, precipitation with various screens, inkjet printing, or other printing processes using different patterns for each dopant. Shows local formation. FIG. 12C shows that the structure of FIG. 12B is heat treated by annealing to move the dopants 18, 19 into the polymer 16. The heat treatment step of FIG. 12C may not be necessary as the solvent used in scrim printing or inkjet printing may transfer the dopant directly into the polymer as in FIGS. 10A-10C.

When using dyes C6 (green), C47 (blue) and nired (red) (dissolved in acetone), which are applied separately to each area of a single PVK film, the acetone solution is applied locally by an eye drop or similar device. Acetone does not remove the PVK film but after a few seconds the fluorescence color of the film changes under UV activation after acetone evaporation.

13A (photo-luminescence) and 13B (electro-luminescence) show the difference between pure PVK film and doped PVK.

The dopant does not need to be pure and may precipitate out with another material. Subsequent processes (or the precipitation process itself) may transfer the dopant to the lower layer. Other materials may be removed or evaporated, or may be part of the final structure that is left as a separate layer, or doped or undoped.

12A-12C may be applied by the method of FIGS. 11A-11C so that the dopant pattern prior to precipitation of the upper polymer film may be introduced into the underlying material.

14A-14C show the step of removing the dopant from the polymer film to the underlying layer. In FIG. 14A the substrate 19 has a lower absorbent film layer 20 deposited thereon. The absorbent layer has a lower chemical potential compared to the required dopant. In FIG. 14B, the doped polymer 2! Is deposited on the absorbent layer 20. Other cycles apply. Instead of heat treatment, a solvent is applied (from the top) that penetrates both the polymer layer 21 and the bottom layer 20 so that the dopant in the top polymer layer can migrate to the bottom layer 20.

15A-15C show the patterned addition of dopant from the top with an impermeable barrier. In FIG. 15A, the undoped polymer 23 is deposited on the substrate 22. In FIG. 15B, a patterned layer opaque with dopants 24, 25, 26 is formed over the polymer 23. In FIG. 15C, the dopant 27 is heat treated by annealing. Or the structure of 15b is introduced into the dopant-containing solvent.

16A-16C show the application of the method of FIG. 12 to the formation of patterned OLEDs of different colors. In FIG. 16A, the undoped polymer 30 is deposited on the ITO layer 29 on the glass substrate 28. ITO can be patterned. By locally doping the polymer 30, local red 31, green 32 and blue 33 regions are formed by locally doping the polymer 30. The red, green and blue regions can be formed by ink jet printing three different solutions on different regions. The heat treatment can then be applied. In FIG. 16C, upper contacts 34, 35, 36 are formed on the red, green, and blue regions by standard methods such as evaporation through a shadow mask. Color dopant application by the use of local solvents in OLED fabrication can change the dopant in the original spin coating film (eg, PBD for electron transport). Thus, some of the dopant needs to be placed with the color dopant solution.

17A-17B show the application of the method of FIG. 12 to forming a passive matrix color OLED display. In FIG. 17A, an ITO line 37 is formed on the glass substrate 38 in one direction. In FIG. 17B a uniform polymer film 39 is applied over the ITO line. In FIG. 17C, the red, green, and blue doped polymer 40 is formed on the ITO line by the step of FIG. 16B. In FIG. 17D, the cathode line 41 as the upper contact is perpendicular to the lower contact line 37. Doping is only necessary at the intersection of the upper and lower contact lines.

18A-18C show the removal of the dopant in the underlying layer in a pattern from the polymer film. In FIG. 18A, an absorbent film 43 is deposited on the substrate 42. In FIG. 18B, the absorbent film 43 is coated with a patterned or patterned impermeable layer 44. Doped polymer 45 is added to layer 44. FIG. 18C shows the annealing effect of the structure of FIG. 18B when the dopant is moved to the lower layer 43, which is not interfered by the impermeable barrier. Transfer of the dopant can be accomplished through the use of the solvent of FIG. 14C.

19A-19B show dopant removal from the top of the unpatterned film. In FIG. 19A, the doped film 47 is deposited on the substrate 46 by dopant solution spin coating. 19B shows that the dopant may not be removed from the film by washing or annealing with a solvent that causes a dopant reduction in layer 47 and the dopant may be moved to the edge of the droplet, leaving little dopant at the center of the droplet.

20A-20C show the patterned removal of the dopant from the top of the film. In FIG. 20A, the doped polymer film 49 is deposited on the substrate 48. In FIG. 20B, a patterned impermeable layer 50 is applied over the doped polymer layer 49. The annealing of the structure of FIG. 20B in FIG. 20C causes the dopant to evaporate in the region without barrier 50. Evaporation may be accomplished by washing with a solvent to remove the dopant in the region without barrier 50 or by treatment with solvent vapor.

21A-21D show active matrix OLED display formation. In FIG. 21A, the glass substrate 51 has a patterned insulator 52 and an electrode 53 formed thereon. The electrodes are connected to transistors (not shown) by pixels. In FIG. 21B, an undoped organic layer 54 is deposited on the structure of FIG. In FIG. 21C locally applied red 55, green 56 and blue 57 dopants are applied by ink jet printing. In FIG. 21D, the upper electrode 58 is applied without a pattern. The upper electrode 58 may be an Al: Li or Mg: Ag cathode.

The method of the present invention can be applied to all organic films as well as polymers. Solvent methods can invite problems to small organic molecule based films but dopants can be precipitated by diffusion by heat treatment by local methods such as evaporation through a mask.

"Undoped" means that the dopant is added or removed and is not doped. Other dopants may be present.

Claims (36)

Providing a substrate; Coating an organic material on the substrate to form an organic film; A method of manufacturing an organic film having a region having modified properties for an organic light emitting diode, comprising applying a doping agent to the film region to modify the properties of the film in the required area. The method of claim 1 wherein the dopant is introduced by applying liquid droplets. A method according to claim 2, wherein the liquid droplets are applied by ink printing. The method of claim 2, wherein the substrate is heated to reduce the size of the denatured region. The method of claim 1 wherein the dopant is applied by screen printing. The method of claim 1, wherein the dopant modifies the luminescence properties of the organic film. 7. A process according to claim 6 wherein the dopant comprises red, green or blue dyes. 8. A process according to claim 7, wherein the dopant comprises coumarin and nired. Providing a substrate; Applying a dopant containing organic coating; Removing the dopant from the coating area. 10. The method of claim 9 wherein the dopant is removed from the coating by a solvent applied to the coating surface. 10. The method of claim 9, wherein the dopant is removed from the coating by annealing to remove the dopant from the coating. The method of claim 10, wherein the mask is patterned on the coating prior to applying the solvent to remove the dopant in the pattern. The method of claim 11 wherein the mask is patterned on the coating prior to annealing to remove the dopant in the pattern. The method of claim 10 wherein the solvent is applied in a pattern on the coating to remove the dopant in the pattern. Providing a dopant containing first layer; Providing a second layer on the first layer; A method for producing a locally modified organic film comprising transferring a dopant from a first layer to a second organic layer. The method of claim 15, wherein the dopant is transferred from the first layer to the second organic layer in the selected region. 17. A method according to claim 16, wherein a masking means is provided on the first layer and the dopant is transferred from the first layer to the unmasked second organic layer prior to providing the second organic layer. The method of claim 16, wherein the dopant containing first layer is patterned on the substrate and the dopant is delivered to the second layer in a pattern of the first layer. Providing a layer of ash 1 material; Providing a dopant in a pattern to the first layer; Providing a second layer comprising an organic material; A method of making a locally modified organic film comprising transferring a dopant in a pattern from a first layer to a second layer. 20. A process according to claim 19 wherein the dopant is introduced by applying liquid droplets. 21. The method of claim 20, wherein the liquid droplets are applied by ink printing. The method of claim 20, wherein the substrate is heated to reduce the size of the denatured region. 20. The method of claim 19, wherein the dopant is applied by screen printing. 20. The method of claim 19, wherein the dopant modifies the luminescent properties of the organic film. The method of claim 24, wherein the dopant comprises a red, green or blue dye. The method of claim 25, wherein the dopant comprises coumarin and nired. 20. The process of claim 19 wherein the dopant is delivered by annealing. Providing a substrate; Applying an organic coating on the substrate; Precipitating a dopant or a dopant containing material on the coating; A method of locally denaturing the nature of an organic film for an OLED comprising transferring the dopant to an organic coating. 29. The method of claim 28, wherein the dopant is applied to the organic coating in a pattern and the dopant forms a pattern in the organic layer after the dopant moves to the organic layer. 30. The method of claim 29, wherein the dopant is applied in liquid droplets. 30. The method of claim 29, wherein the liquid droplets are applied by ink jet printing. 30. The method of claim 29, wherein a dopant is applied by patterning the dry powder onto the organic coating. 30. The method of claim 29, wherein the dopant is applied by contacting the dopant containing patterned thin film with an organic coating. 30. The method of claim 29, wherein the dopant is transferred to the organic layer by heat application. 31. The method of claim 30, wherein the substrate is heated to reduce the size of the denatured region. Providing an organic film; Covering the organic layer with a patterned barrier; Dopant or dopant-containing material is applied over the organic layer and the barrier; Moving the dopant to the organic film in the area exposed through the barrier.