Flash Light Illumination Method and Organic Electronic Device Elements Obtainable This Way

Abstract

The present invention relates to a method comprising the steps: a) providing a layered structure applicable for preparing an organic electronic device, comprising: aa) a substrate comprising a first electrode structure and a non-electrode part; bb) a grid formed by a grid material, wherein open areas of the grid are arranged above at least a part of the first electrode structure and the grid material is arranged above at least a part of the non-electrode part; and cc) a layer stack comprising at least one redox-doped layer having a conductivity of at least 1E?7 S/cm, the layer stack being deposited on the grid; wherein the optical density measured by absorption spectroscopy of the grid material is higher than the optical density of the open areas; and b) irradiating light pulses having a duration of <10 ms and an energy of 0.1 to 20 J/cm.sup.2 per pulse, alternatively 1 to 10 J/cm.sup.2, onto the layered structure; an organic electronic device obtainable this way and a device comprising said organic electronic device.

Claims

1. A method comprising the steps: a) providing a layered structure applicable for preparing an organic electronic device, comprising: aa) a substrate comprising a first electrode structure and a non-electrode part; bb) a grid formed by a grid material, wherein open areas of the grid are arranged above at least a part of the first electrode structure and the grid material is arranged above at least a part of the non-electrode part; and cc) a layer stack comprising at least one redox-doped layer having a conductivity of at least 1E?7 S/cm, the layer stack being deposited on the grid; wherein the optical density measured by absorption spectroscopy of the grid material is higher than the optical density of the open areas; and b) irradiating light pulses having a duration of <10 ms and an energy of 0.1 to 20 J/cm2 per pulse, onto the layered structure.

2. Method according to claim 1, wherein the layer stack further comprises an emission layer.

3. Method according to claim 1, wherein the grid material comprises a photoresist.

4. Method according to claim 1, wherein the layered structure further comprises a second electrode arranged on the top of the layer stack.

5. Method according to claim 4, wherein the layered structure further comprises a barrier layer arranged on top of the second electrode.

6. Method according to claim 1, wherein irradiating is performed by using of a flash lamp.

7. Method according to claim 1, wherein the total thickness of the layer stack is more than 10 nm and less than 5000 nm, and/or the thickness of the grid is larger than the thickness of the at least one redox-doped layer.

8. Method according to claim 1, wherein: i. the at least one redox-doped layer consists of a redox-dopant; or ii. the at least one redox-doped layer comprises a redox-dopant and a matrix material, the matrix material being a charge transport material; or iii. the at least one redox-doped layer is a double layer consisting of a first layer consisting of an injection material and a second layer consisting of a charge transport material which may be redox-doped or undoped.

9. Method according to claim 8 wherein the redox dopant is: 1. a p-type dopant selected from 1.1. an organic or organometallic molecular dopant having a molecular weight of about 350 to about 1700 and may be selected from dimalonitrile compound, an aromatic/heteroaromatic nitrile compound, a fullerene derivative or a radialene derivative of formula 1, wherein Ar1-3 are the same or different and independently selected from aryl or heteroaryl; ##STR00010## or 1.2. a transition metal oxide, which may be selected from MoO.sub.3 and V.sub.2O.sub.5; or 1.3. a lewis acid, which may be a (trifluoromethanesulfonyl)imide compound and may be selected from the bis(trifluoromethansulfanoyl)imides of a metal of groups 1 to 12 of the periodic system of elements, wherein the metal of Groups 1 to 12 may be selected from Li, Mg, Ba, Sc, Mn, Cu, Ag or mixtures thereof Or; 2. an n-type dopant selected from 2.1. an organic or organometallic molecular dopant having a molecular weight of about 300 to about 1500, or 2.2. a metal dopant selected from the group consisting of a metal halide having a molecular weight of about 25 to about 500, a metal complex having a molecular weight of about 150 to about 1500, and a zero-valent metal selected from the group consisting of alkali metal, alkaline earth metal, and rare earth metals.

10. Method according to claim 8, wherein the injection material is: 1. a p-type material selected from 1.1. an organic or organometallic molecular dopant having a molecular weight of about 350 to about 1700, which may be selected from dimalonitrile compound, an aromatic/heteroaromatic nitrile compound, a fullerene derivative or a radialene derivative of formula 1, wherein Ar1-3 are the same or different and independently selected from aryl or heteroaryl; ##STR00011## or 1.2. a transition metal oxide, which may be selected from MoO.sub.3 and V.sub.2O.sub.5; or 1.3. a lewis acid, which may be a (trifluoromethanesulfonyl)imide compound and may be selected from the bis(trifluoromethansulfanoyl)imides of metals of groups 1 to 12 of the periodic system of elements, the metal may be selected from Li, Mg, Ba, Sc, Mn, Cu, Ag or mixtures thereof; or 1.4. a metal halide, which may be MgF.sub.2 or; 2. an n-type material selected from 2.1. an organic or organometallic molecular dopant having a molecular weight of about 300 to about 1500, or 2.2. a metal dopant selected from the group consisting of a metal halide having a molecular weight of about 25 to about 500, a metal complex having a molecular weight of about 150 to about 1500, and a zero-valent metal of Groups 1 to 12 selected from the group consisting of alkali metal, alkaline earth metal, and rare earth metals.

11. Method according to claim 1, wherein the first electrode structure constitutes a variety of pixels on the substrate having a pixel gap of less than 50 ?m, and a pixel pitch less than 150 ?m.

12. Organic electronic device obtainable by a method according to claim 1.

13. Organic electronic device according to claim 12, wherein the organic electronic device is an OLED, a photodetector, a transistor or a solar cell.

14. Device comprising the organic electronic device according to claim 12.

15. Device according to claim 12, wherein the device is a display device.

16. Device according to claim 13, wherein the first electrode structure constitutes pixels of the display device.

17. Method according to claim 6, wherein the flash lamp comprises a Xenon, LED, or Laser light source.

18. Method according to claim 7, wherein the total thickness of the layer stack is more than 30 nm and less than 300 nm.

19. Method according to claim 7, wherein the thickness of the grid is more than 500 nm and less than 10000 nm.

20. Method according to claim 1, wherein the first electrode structure constitutes a variety of pixels on the substrate having a pixel gap of more than 1 ?m and less than 30 ?m, and a pixel pitch of more than 2 ?m and less than 125 ?m.

Description

EXPERIMENTAL PART

[0134] Following, the disclosure will be described in detail by referring to specific exemplary materials and conditions for performing the method by referring to the enclosed figures. In the figures show:

[0135] FIG. 1 Schematic view of the substrate with the layered structure placed under the fluid cooled Xenon flash lamp

[0136] FIG. 2 Test layout for measurements of the cross-talk current

[0137] FIG. 3 Schematic cross-sectional view of the layered structure a) before irradiation, b) with irradiation, c) after irradiation.

[0138] FIG. 4 Resistance ratio of the redox-doped layer with and without grid

[0139] FIG. 5 Top view (large and detailed) of the grid on the substrate in a pixelated OLED layout

[0140] FIG. 6 Cross-talk current ratio before and after irradiation

[0141] FIG. 7 Optical density of grid vs first electrode

[0142] Table 1 Cross-talk currents on test layout for 40 ?m channel at 5V

[0143] FIG. 1 shows a schematic view of the layered structure 10 being arranged below the source of the pulsed radiation 11 during irradiation at a distance of 25 mm. The layered structure 10 may be mounted on a sample holder 12. The method according to the disclosure utilizes light pulses based on single visible light flashes t?2 ms. Thus, only little heat is introduced to the substrate, assuring temperature increase only locally and no heat dissipation and low thermal stress to non-irradiated areas.

[0144] FIG. 2 shows a schematic view of the test layout used to measure the cross-talk current between the first electrode of a first pixel 21 and the first electrode of a second pixel 22. The pixel gap on test layout corresponds to the direct smallest distance between first electrode of a pixel 21 and the first electrode of a second pixel 22. On this test layout this pixel gap is 40 ?m which is very similar to real pixel gaps used for instance in AMOLED display production. The voltage used was 5 V. The currents were measured with a parameter analyzer Keithley S4200 as provided by Tektronix, Beaverton, USA. A robot was used to contact the electrodes. On top of the first electrode the 1.5 ?m thick polyimide grid 23 was deposited using photolithographic process. The redox-doped layer 24 was a hole-injection layer (HIL). The HIL comprised the compounds

##STR00008##

as charge transport material and

##STR00009##

as redox dopant in the weight ratio of 92:8. The materials were co-deposited by vapor deposition. The layer thickness of the redox-doped layer was 10 nm.

[0145] FIG. 3 shows a schematic cross-sectional view of the layered structure a) before irradiation, b) with irradiation, c) after irradiation. The layered structure comprises a substrate 31, a grid material 32, a layer stack 33, a first electrode of a first pixel 34 and a first electrode of a second pixel 35. Before irradiation (FIG. 3a) the redox-doped layer in the layer stack has the same conductivity above the area of the first electrode and above the grid material of about 4E?5 S/cm, calculated as follows:

[00001]$\mathrm{Resistance}=\frac{5.Math..Math.V}{I_{\mathrm{Channel}@5.Math..Math.V}}$$b=\frac{\mathrm{Resistance}}{\mathrm{Channel}.Math..Math.\mathrm{length}}$$?=\frac{1}{b.Math.\mathrm{Channel}.Math..Math.\mathrm{width}.Math.\mathrm{Layer}.Math..Math.\mathrm{thickness}}$$\begin{array}{c}\mathrm{Channel}.Math..Math.\mathrm{width}=9.5.Math..Math.\mathrm{cm}\\ \begin{array}{c}\mathrm{Layer}.Math..Math.\mathrm{thickness}=.Math.10.Math..Math.\mathrm{nm}\\ =.Math.10.Math..Math.e.Math.\text{-}.Math.7.Math..Math.\mathrm{cm}\end{array}\\ {?}_{\mathrm{before}.Math..Math.\mathrm{irradiation}}=4.09.Math..Math.e.Math.\text{-}.Math.5.Math..Math.S.Math.\text{/}.Math.\mathrm{cm}\end{array}$$\begin{array}{c}b=.Math.257259.Math..Math.\mathrm{ohms}.Math.\text{/}.Math.\mathrm{.Math.m}\\ =.Math.2.57.Math..Math.e.Math..Math.9.Math..Math.\mathrm{ohms}.Math.\text{/}.Math.\mathrm{cm}\end{array}$

[0146] After irradiation of the layered structure (FIG. 3c) is was surprisingly found that the redox-doped layer in the layer stack 33 has an unchanged conductivity above the area of the first electrode (layer stack area 37) whereas in the area above the grid material (layer stack area 36) the cross-talk current is significantly reduced. After irradiation cross-talk currents were very small (<100 pA). Therefore, conductivity could not be calculated in a meaningful way. The influence of the measurement setup (wire leakage current, noise) was dominating.

[0147] As a consequence of this, the cross-talk current which can flow through the redox-doped layer between the first electrode of a first pixel 34 and the first electrode of a second pixel 35 is also significantly reduced. The root cause of this effect is likely an interaction of the grid material with the irradiated light having an annihilating effect on the conductivity in the redox-doped layer in the layer stack 33. Due to the large aspect ratio of grid thickness vs thickness of the layer stack the effect does not significantly reduce the conductivity of the layer stack in layer stack area 37.

[0148] FIG. 4 shows the resistance ratios of the redox-doped layer on the test layout with grid and without grid for different irradiation energy densities. The resistance of the redox doped layer increases exponentially with irradiation energy density when the grid is used. At the same time the resistance of the redox-doped layer remains unchanged after irradiation if no grid is used.

[0149] FIG. 5 shows an example top view (large and detailed) of the grid, formed by a grid material 51 and having open areas 52, on an ITO substrate in a pixelated OLED layout. The pixel pitch is 125 ?m and the pixel gap is 30 ?m.

TABLE-US-00001 TABLE 1 Cross-talk currents on test layout for 40 ?m channel at 5 V, redox-doped layer thickness 10 nm, current measured with S4200/robot Cross-talk Irradiation current current Pulse energy Pulse before current after reduction density length treatment treatment ratio Sample [J/cm.sup.2] [ms] [nA] [nA] I.sub.after/I.sub.before Reference 0 1 450.4 488.300 1/0.92 Example Example 1 4 1 464.3 15.201 1/30.5 Example 2 4.5 1 459.4 1.196 1/384 Example 3 5 1 462.1 0.212 1/2185

[0150] Table 1 shows the measured cross-talk currents at 5 V on test layout for 40 ?m channel which corresponds in this case to the pixel pitch. The reference example was not irradiated. The inventive example 1 was irradiated with a pulse energy density of 4 J/m.sup.2, the inventive example 2 was irradiated with a pulse energy density of 4.5 J/m.sup.2 and the inventive example 3 was irradiated with a pulse energy density of 5 J/m.sup.2. Cross-talk current decreases significantly with pulse energy density showing a current reduction by more than a factor of 1000 for example 3. Already for example 2 the cross-talk current is reduced to <1 nA.

[0151] FIG. 6 depicts the values in Table 1 graphically.

[0152] FIG. 7 shows the optical density of the grid material and the optical density of the first electrode. In the sense of this disclosure it is important that the optical density of the grid material is higher than the optical density of the first electrode to bring about the desired technical effect. Experimental results on reference example and examples 1-3 were obtained using a Xenon flash lamp. But any high power source with appropriate light spectrum capable of producing defined short pulses in millisecond range (e.g. LED) is suitable in the sense of this disclosure. The type and wavelength of the irradiation source is not particularly restricted or defined. Important is that the optical density of the grid material is higher than the optical density of the first electrode over a large usable wavelength range.

[0153] The features disclosed in the foregoing description, in the claims and the accompanying drawings may, both separately and in any combination, be material for realizing the disclosed method in diverse forms thereof.