Indium gallium titanium oxide target material, method for preparing same, and use thereof

Abstract

This invention belongs to the field of oxide target technology, specifically disclosing an indium gallium titanium oxide (IGaTi) target, its preparation method, and its applications. The raw materials for preparing the IGaTi target of this invention, by mass parts, include 95-99 parts of indium oxide, 0.5-2 parts of gallium oxide, and 0.6-3 parts of titanium dioxide. By doping an indium oxide-based target with appropriate proportions of gallium oxide and titanium dioxide, this invention can achieve excellent light transmittance in the oxide film prepared from the target while maintaining a relatively low resistivity. Furthermore, the oxide film prepared from this target exhibits good mechanical flexibility, making it more suitable for flexible OLEDs. This invention also provides a method for preparing the IGaTi target.

Description

Technical Field

[0001] This invention relates to the field of oxide target technology, and in particular to an indium gallium titanium oxide target, its preparation method, and its application. Background Technology

[0002] In recent years, flexible organic light-emitting diodes (OLEDs) have attracted widespread attention due to their unique performance. The design flexibility afforded by their flexibility has opened up new possibilities for OLED applications. The bending or folding deformation of screens has led to innovative foldable or bendable products, which have been applied in foldable phones and large-area curved screens. Foldable smartphones using flexible screens have increased screen size without compromising user convenience. The technological advantage of screen flexibility can be attributed to advancements in flexible electrodes, which are crucial for achieving the flexibility required for OLEDs. Given the enormous potential of flexible transparent electrodes in applications such as flexible or foldable OLEDs, the development of transparent electrodes with low sheet resistance, excellent optical transmittance, and superior mechanical flexibility is imperative.

[0003] Currently, many flexible transparent electrode materials have been proposed as alternatives to traditional ITO thin films. However, thin ITO electrodes continue to be used as the bottom electrodes for flexible OLEDs, primarily driven by the advantageous properties of ITO, including its low sheet resistance, high transmittance, and well-developed manufacturing process. Despite extensive exploration of other materials, these qualities and properties make thin ITO electrodes the preferred choice for ensuring optimal performance in flexible OLEDs. However, with the growing interest in flexible displays and the increasing demand for transparent conductors that can overcome the challenges of flexible configurations, current ITO-based electrodes, exhibiting a lower mechanical strain tolerance than other layers in the device, are increasingly failing to meet industry and market demands.

[0004] Therefore, there is an urgent need to develop a transparent conductor material that can replace ITO, which has good mechanical flexibility while ensuring good conductivity and transparency under large mechanical strain. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention provides an indium gallium titanium oxide (IGaTi) target. The IGaTi target of this invention has a low resistivity, and the oxide film prepared from it possesses excellent light transmittance and mechanical flexibility, making it well-suited for use in flexible OLEDs.

[0006] The present invention also provides a method for preparing an indium gallium titanium oxide target.

[0007] The present invention also provides a flexible oxide thin film.

[0008] The present invention also provides a flexible OLED.

[0009] This invention also proposes the application of indium gallium titanium oxide (IGaTi) sputtering targets in the field of displays.

[0010] In a first aspect, the present invention provides an indium gallium titanium dioxide target material, wherein the raw materials for preparation include 95-99 parts of indium oxide, 0.5-2 parts of gallium oxide and 0.6-3 parts of titanium dioxide by mass.

[0011] According to specific embodiments of the present invention, the indium gallium titanium oxide target provided by the present invention has at least the following beneficial effects:

[0012] The indium gallium titanium oxide target of the present invention has a high relative density and a relatively small average grain size, and can make the oxide film prepared by the target have excellent light transmittance and mechanical flexibility while maintaining a relatively low resistivity of the target.

[0013] This invention uses amorphous gallium and titanium co-doped indium oxide, where Ga (62 p.m.) and Ti (60.5 p.m.) have similar ionic radii to In (80 p.m.). Therefore, compared with other doped oxides, Ga and Ti doping produces less stress, resulting in a smaller decrease in the electron mobility of the target material. Furthermore, Ga and Ti have high metal-oxygen bonding capabilities (Ga-O, Ti-O), which can reduce the presence of oxygen vacancies in the indium oxide matrix. Additionally, titanium doping can enhance the performance of Ti... 4+ Replace In 3+ In addition, Ti doping provides free electrons and also has a strong Lewis acid strength, which causes electrons to move away from the strong polarization of the O2p valence band, thereby causing charge screening, reducing electron scattering effect, and ultimately increasing electron mobility and improving the conductivity of the target material and oxide film.

[0014] This invention further optimizes the doping amount and doping ratio of gallium oxide and titanium dioxide in the indium oxide target, further improving the overall performance of the target and oxide film, especially enhancing the flexibility of the oxide film prepared by this invention, enabling it to maintain conductivity and transparency under large mechanical strain, thus allowing it to be better applied in the fields of flexible OLEDs and flexible displays.

[0015] According to some embodiments of the present invention, the raw materials for preparation include, by mass parts, 96.12 to 98.48 parts of indium oxide, 0.67 to 1.34 parts of gallium oxide, and 0.85 to 2.54 parts of titanium dioxide.

[0016] According to some embodiments of the present invention, the raw materials for preparation include, by mass parts, 96.12 to 97.64 parts of indium oxide, 0.67 to 1.34 parts of gallium oxide, and 1.69 to 2.54 parts of titanium dioxide.

[0017] According to some embodiments of the present invention, the raw materials for preparation further include 1 to 5 parts of dispersant and 1 to 5 parts of binder.

[0018] According to some embodiments of the present invention, the raw materials for preparation further include 2 to 4 parts of dispersant and 2 to 4 parts of binder.

[0019] According to some embodiments of the present invention, the dispersant includes at least one of polyvinylpyrrolidone, polyacrylamide, polyethylene glycol, or hydrogenated nitrile rubber.

[0020] According to some embodiments of the present invention, the adhesive includes at least one of polyvinyl alcohol, sodium polyacrylate, butyl rubber, or cyanoacrylate.

[0021] A second aspect of the present invention provides a method for preparing the indium gallium titanium oxide target described in the first aspect of the present invention, comprising the following steps:

[0022] S1. Mix the indium oxide, gallium oxide and titanium dioxide, then add water, dispersant and binder and mix and grind.

[0023] S2. Spray drying and granulation to obtain mixed powder;

[0024] S3. Cold isostatic pressing and sintering yield indium gallium titanium oxide target material.

[0025] According to some embodiments of the present invention, the grinding in step S1 is ball milling.

[0026] According to some embodiments of the present invention, the ball milling in step S1 is divided into three steps, specifically, the indium oxide, the gallium oxide and the titanium dioxide are mixed and ball milled for the first time, water and dispersant are added and ball milling is performed for the second time, and then a binder is added and ball milling is performed for the third time.

[0027] According to some embodiments of the present invention, the cold isostatic pressing pressure in step S3 is 100-400 MPa, and the holding time is 2-10 min.

[0028] According to some embodiments of the present invention, the sintering in step S3 is performed by sequentially holding at 500-600°C for 1-3 hours, holding at 900-1100°C for 3-5 hours, holding at 1350-1400°C for 6-8 hours in an oxygen atmosphere, and holding at 900-1100°C for 1-3 hours.

[0029] According to some embodiments of the present invention, the sintering in step S3 is as follows: the statically pressed preform is placed in a sintering furnace, heated to 500-600°C at a heating rate of 2-4°C / min and held for 1-3 hours; heated to 900-1100°C at a heating rate of 0.5-2°C / min and held for 3-5 hours; oxygen is introduced, and the preform is heated to 1350-1390°C at a heating rate of 0.2-1°C / min under an oxygen atmosphere and held for 4-6 hours; the preform is heated to 1390-1420°C at a heating rate of 0.2-1°C / min under an oxygen atmosphere and held for 1-3 hours; oxygen is stopped, and the preform is cooled to 900-1100°C at a cooling rate of 0.5-2°C / min and held for 1-3 hours; finally, the preform is cooled to room temperature at a cooling rate of 0.5-2°C / min.

[0030] In a third aspect, the present invention provides a flexible oxide film, which is made from an indium gallium titanium oxide target material as described in the first aspect of the present invention, wherein the oxide film has a light transmittance of 92% to 99%.

[0031] In a fourth aspect, the present invention provides a flexible OLED comprising the flexible oxide film described in the third aspect of the present invention.

[0032] A fifth aspect of the present invention provides the application of the indium gallium titanium oxide target material described in the first aspect of the present invention, the flexible oxide film described in the third aspect of the present invention, and the flexible OLED described in the fourth aspect of the present invention in the field of displays.

[0033] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Detailed Implementation

[0034] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0035] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0036] Example 1

[0037] This embodiment provides an indium gallium titanium oxide target and a method for its preparation.

[0038] The oxide raw material composition of the indium gallium titanium dioxide target material in this embodiment is as follows by mass parts: 98.48 parts of indium oxide (In2O3), 0.67 parts of gallium oxide (Ga2O3) and 0.85 parts of titanium dioxide (TiO2). In addition, the raw materials also include 1.33 parts of deionized water, 3 parts of dispersant and 3.385 parts of binder.

[0039] The dispersant is polyvinylpyrrolidone (other dispersants may include polyacrylamide, polyethylene glycol, and hydrogenated nitrile rubber), and the binder is polyvinyl alcohol (other binders may include sodium polyacrylate, butyl rubber, and cyanoacrylate).

[0040] This embodiment also provides a method for preparing the indium gallium titanium oxide target, the specific steps of which are as follows:

[0041] 1) Mix indium oxide powder, gallium oxide powder, and titanium dioxide powder, and ball mill them for 1 hour to ensure uniform mixing of the oxide powders. The ball milling speed is 400 r / min, and the zirconium bead particle size is 2.0 mm. Then add 1.33 parts of deionized water and dispersant, and ball mill for a second time for 40 hours. The ball milling speed is 1100 r / min, and the zirconium bead particle size is 0.65 mm. Add binder to the mixed slurry, and ball mill for a third time for 1 hour. The ball milling speed is 1100 r / min, and the zirconium bead particle size is 0.3 mm.

[0042] 2) After ball milling, the slurry is spray-dried and granulated to obtain a mixed powder;

[0043] 3) Inject the mixed powder into the mold, and perform molding (80MPa, 5min) and cold isostatic pressing. The cold isostatic pressing is held at 220MPa for 5min to obtain the target blank.

[0044] 4) Place the green blank in a sintering furnace for sintering. First, raise the temperature to 550℃ at a rate of 3℃ / min and hold for 2 hours. Second, raise the temperature to 1000℃ at a rate of 1℃ / min and hold for 4 hours. Third, introduce oxygen and raise the temperature to 1380℃ at a rate of 0.5℃ / min, and hold for 5 hours in an oxygen atmosphere. Then, raise the temperature to the maximum temperature of 1400℃ at a rate of 0.5℃ / min and hold for 2 hours. After holding, stop introducing oxygen and lower the temperature to 1000℃ at a rate of 1℃ / min, and hold for 2 hours. Finally, lower the temperature to room temperature at a rate of 1℃ / min. After sintering and cooling, indium gallium titanium oxide target material is obtained.

[0045] In this embodiment, further processing steps are also included on the indium gallium titanium oxide target material for subsequent practical use or measurement. Specifically:

[0046] The sintered target material is processed and polished according to the size requirements to obtain the finished target material.

[0047] Example 2

[0048] This embodiment provides an indium gallium titanium oxide target and a method for its preparation.

[0049] The only difference between this embodiment and Example 1 is the mass fraction of the metal oxide raw material components: this embodiment uses 97.81 parts of indium oxide, 1.34 parts of gallium oxide, and 0.85 parts of titanium dioxide, while the remaining raw material components and preparation methods are the same as in Example 1.

[0050] Example 3

[0051] This embodiment provides an indium gallium titanium oxide target and a method for its preparation.

[0052] The only difference between this embodiment and Example 1 is the mass fraction of the metal oxide raw material components: this embodiment uses 97.64 parts of indium oxide, 0.67 parts of gallium oxide, and 1.69 parts of titanium dioxide, while the remaining raw material components and preparation methods are the same as in Example 1.

[0053] Example 4

[0054] This embodiment provides an indium gallium titanium oxide target and a method for its preparation.

[0055] The only difference between this embodiment and Example 1 is the mass fraction of the metal oxide raw material components: this embodiment uses 96.97 parts of indium oxide, 1.34 parts of gallium oxide, and 1.69 parts of titanium dioxide, while the remaining raw material components and preparation methods are the same as in Example 1.

[0056] Example 5

[0057] This embodiment provides an indium gallium titanium oxide target and a method for its preparation.

[0058] The only difference between this embodiment and Example 1 is the mass fraction of the metal oxide raw material components: this embodiment uses 96.79 parts of indium oxide, 0.67 parts of gallium oxide, and 2.54 parts of titanium dioxide, while the remaining raw material components and preparation methods are the same as in Example 1.

[0059] Example 6

[0060] This embodiment provides an indium gallium titanium oxide target and a method for its preparation.

[0061] The only difference between this embodiment and Example 1 is the mass fraction of the metal oxide raw material components: this embodiment uses 96.12 parts of indium oxide, 1.34 parts of gallium oxide, and 2.54 parts of titanium dioxide, while the remaining raw material components and preparation methods are the same as in Example 1.

[0062] Comparative Example 1

[0063] This comparative example provides a conventional tin-doped indium oxide (ITO) target and its preparation method.

[0064] The only difference between this comparative example and Example 1 is the metal oxide raw materials: this comparative example uses 90.00 parts of indium oxide and 10.00 parts of tin oxide (SnO2), while the other raw material components and preparation methods are the same as in Example 1.

[0065] Comparative Example 2

[0066] This comparative example provides a gallium-doped indium oxide target and its preparation method.

[0067] The only difference between this comparative example and Example 1 is the metal oxide raw materials: this comparative example uses 98.66 parts of indium oxide and 1.34 parts of gallium oxide, while the other raw material components and preparation methods are the same as in Example 1.

[0068] Comparative Example 3

[0069] This comparative example provides a titanium-doped indium oxide target and its preparation method.

[0070] The only difference between this comparative example and Example 1 is the metal oxide raw materials used: this comparative example uses 97.46 parts of indium oxide and 2.54 parts of titanium dioxide, while the other raw material components and preparation methods are the same as in Example 1.

[0071] Comparative Example 4

[0072] This comparative example provides an indium gallium titanium oxide target and its preparation method.

[0073] The only difference between this comparative example and Example 1 is the mass fraction of the metal oxide raw material components: this example uses 95.94 parts of indium oxide, 0.67 parts of gallium oxide, and 3.39 parts of titanium dioxide, while the remaining raw material components and preparation methods are the same as in Example 1.

[0074] Comparative Example 5

[0075] This comparative example provides an indium gallium titanium oxide target and its preparation method.

[0076] The only difference between this comparative example and Example 1 is the mass fraction of the metal oxide raw material components: this example uses 95.27 parts of indium oxide, 1.34 parts of gallium oxide, and 3.39 parts of titanium dioxide, while the remaining raw material components and preparation methods are the same as in Example 1.

[0077] Performance testing:

[0078] 1. Performance tests were conducted on the indium oxide target materials prepared in the above embodiments and comparative examples. Density was measured using the Archimedes displacement method, and the relative density was the ratio of the actual density to the theoretical density measured by the displacement method. Metallographic analysis was performed on the target samples, and the average grain size was measured using the cross-section method. Resistivity was measured using a resistivity meter with the four-point probe method. Each target material was then sputtered using a magnetron sputtering machine to form a 100 nm thick oxide film on a 10*10 mm plastic substrate. Transmittance was measured using a dual-beam UV-Vis spectrophotometer. The oxide raw materials used and performance parameters in each embodiment and comparative example are shown in Table 1.

[0079] Table 1. Results of oxide raw material usage and performance parameters in each embodiment and comparative example.

[0080]

[0081]

[0082] As shown in Table 1, the test results of this invention, by multi-doping gallium oxide and titanium dioxide into the indium oxide-based target, have a significant impact on the performance of the target and the prepared oxide film. By changing the doping composition and ratio, the overall performance of the target and the oxide film is improved. Compared with traditional ITO targets, the indium gallium titanium oxide target using the method of this invention can maintain a low resistivity while producing an oxide film with excellent light transmittance. Furthermore, the target of this invention has a relatively high density and a small average grain size.

[0083] Comparing Examples 1 and 2, Examples 3 and 4, and Comparative Example 2, it can be seen that gallium doping in the present invention has varying degrees of influence on the relative density, resistivity, and transmittance of the target material. With increasing gallium doping amount, the relative density and transmittance of the target material increase, but its resistivity also tends to increase, which is detrimental to electron migration. Therefore, gallium doping in the present invention should not be excessive. Comparing Examples 1 and 3, Examples 2, 4, and 6, and Comparative Example 2, it can be seen that titanium doping in the present invention has a significant impact on the resistivity of the target material and the transmittance of the prepared oxide film. Increasing the titanium dioxide doping ratio helps to reduce the resistivity of the target material, and also improves the transmittance of the film. However, by comparing Examples 1, 3, 5, and Comparative Example 4 with Examples 2, 4, 6, and Comparative Example 5, it can be seen that after the titanium element doping exceeds a certain value, the resistivity actually shows an increasing trend. This is because when the titanium element is doped in excess, the element cannot mix well with the matrix and instead agglomerates, leading to abnormal grain growth during sintering. As a result, the resistivity increases instead of decreasing, and the average grain size of the target material also increases. Conversely, the relative density decreases significantly. Therefore, the amount of titanium element doping needs to be within a certain range.

[0084] The performance test results of Comparative Example 3 show that only a certain amount of titanium dioxide was doped in Comparative Example 3, resulting in a target material with a relative density of less than 90%. A relatively low relative density will reduce the target material's lifespan, result in poor heat dissipation performance, and make the target sputtering process prone to instability, thus affecting the quality of the prepared oxide film.

[0085] As can be seen from Comparative Examples 4 and 5, the relative performance of the target material does not show an increasingly better trend as the doping ratio increases. This is likely because if the doping ratio is too high, the doping elements and the indium oxide base cannot be uniformly mixed and sintered, resulting in a decrease in performance. Furthermore, the larger average grain size of the target material also leads to lower target strength.

[0086] As analyzed above, both gallium oxide and titanium dioxide doping affect the resistivity of the target material. With increasing gallium oxide doping ratio, the target resistivity tends to increase. However, the effect of increasing titanium dioxide doping ratio on resistivity is opposite to that of gallium oxide. Furthermore, test results show that titanium dioxide has a better effect on resistivity than gallium oxide, and increasing the titanium dioxide doping amount can reverse the trend of gallium oxide reducing target resistivity. Therefore, Examples 4 and 6 of this invention both achieve very low target resistivity, and the oxide films prepared with this target material have excellent light transmittance. However, the target material in Example 6 has a lower relative density. Analysis suggests that the Ga-O and Ti-O combination prevents the presence of oxygen vacancies in the In2O3 matrix. The electrostatic force of oxygen vacancies on electrons generates ion scattering centers within the IGTO film. The reduction of oxygen vacancies increases the combined performance of carrier mobility and light transmittance. Furthermore, Ti... 4+ Replace In 3+ It can provide more free electrons, compensating for the low carrier concentration. The high mobility caused by titanium and the low oxygen vacancy concentration caused by doping give the target material of this invention and the thin film prepared there two major advantages: low resistivity and high transmittance.

[0087] 2. Bending fatigue tests were performed on the oxide films using a bending tester;

[0088] After the target material of Example 4 of the present invention and the conventional ITO target material of Comparative Example 1 were made into thin films by the aforementioned sputtering process, thousands of bending fatigue tests with different bending radii were conducted, and the results are shown in Table 2.

[0089] Table 2 Results of bending fatigue test on oxide films

[0090] Serial Number Thin film categories Number of bends Bending radius / mm Increase in resistivity (%) 1 IGTO 5000 3 0 2 IGTO 5000 4 5.6 3 ITO 5000 3 3.4 4 ITO 5000 4 187 5 ITO 2500 3 0

[0091] The test results above show that when the number of bending cycles is 5000 and the bending radius is 3mm or 4mm, the resistivity of the ITO film increases more easily and significantly after the bending fatigue test. In contrast, the resistivity of the film prepared by the target material of this invention does not change much, and the increase in resistivity is significantly reduced compared to the ITO film. This indicates that the IGTO film prepared by this invention has superior flexibility and durability compared to oxide films prepared by traditional ITO targets. Furthermore, the IGTO target material of this invention can be used to form the IGTO film using a non-destructive deposition technique, reducing damage to the substrate during film formation and thus allowing it to perform more effectively.

[0092] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A method for preparing an indium gallium titanium oxide target, characterized in that, Includes the following steps: S1. By mass, mix 96.12~97.64 parts of indium oxide, 0.67~1.34 parts of gallium oxide and 1.69~2.54 parts of titanium dioxide, then add water, 1~5 parts of dispersant and 1~5 parts of binder and mix and grind. S2. Spray drying and granulation to obtain mixed powder; S3. Cold isostatic pressing and sintering yields indium gallium titanium oxide target material. The sintering in step S3 is as follows: holding at 500~600℃ for 1~3h, holding at 900~1100℃ for 3~5h, holding at 1350~1400℃ for 6~8h in an oxygen atmosphere, and holding at 900~1100℃ for 1~3h.

2. The preparation method according to claim 1, characterized in that, The dispersant includes at least one of polyvinylpyrrolidone, polyacrylamide, polyethylene glycol, or hydrogenated nitrile rubber. And / or, the adhesive includes at least one of polyvinyl alcohol, sodium polyacrylate, butyl rubber, or cyanoacrylate.

3. The preparation method according to claim 1, characterized in that, The cold isostatic pressing pressure in step S3 is 100~400MPa, and the holding time is 2~10min.

4. A flexible oxide thin film, characterized in that, The indium gallium titanium oxide target prepared by the method of any one of claims 1 to 3 is prepared by magnetron sputtering; The transmittance of the oxide film is 92% to 99%.

5. A flexible OLED, characterized in that, Including the flexible oxide film as described in claim 4.

6. The indium gallium titanium oxide target material prepared by the method of any one of claims 1 to 3, the flexible oxide film of claim 4, or the flexible OLED of claim 5 are used in the field of displays.

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