A metal oxide transparent conductive film and its application

Abstract

The present invention discloses a metal oxide transparent conductive film, wherein the metal oxide is: a small amount of rare earth oxide ReO is doped into an indium-containing metal oxide MO-In2O3 as a photogenerated carrier conversion center to form (In2O3) x (MO) y (ReO) z Transparent conductive material. The present invention controls the carrier concentration and improves the mobility by introducing rare earth oxide materials into indium-based metal oxides; the rare earth ions in the rare earth oxides have lower electronegativity, and the ionic bonds Ln-O formed with oxygen ions have higher bond breaking energy, so the oxygen vacancy concentration in the In2O3 film can be effectively controlled. Rare earth ions have an ionic radius comparable to that of indium ions, which can reduce defect scattering caused by structural mismatch, and thus better maintain their high mobility characteristics. The present invention also provides an application of the metal oxide transparent conductive film.

Description

Technical Field

[0001] The present invention relates to the technical field of coating technology, in particular to the preparation of metal oxide transparent conductive films (TCO) in flat panel displays and solar cells, and specifically to a metal oxide transparent conductive film and its application. Background Art

[0002] In the widely used indium (In)-based metal oxide transparent conductive film (TCO) system, indium ions (In 3+ ) Due to its relatively large ionic radius, the In-In bond orbital overlap is large, making its 5s orbital an efficient carrier transport channel. The most mature and widely used TCO material is ITO (In2O3:SnO2=90:10wt.%) film, in which In 3+ Providing efficient conductive channels, Sn 4+ It can act as a donor to provide carriers and reduce the distortion of In-O bonds. However, in the ITO system, since the bond breaking energy of In-O is low after indium and oxygen form a bond, there are a large number of oxygen vacancy defects in the pure indium oxide (In2O3) film. Oxygen vacancies are a typical carrier donor, which will lead to excessive carrier concentration. Excessive carrier concentration will cause surface plasma effect, resulting in greater absorption of ITO film in the infrared band. Therefore, the current application of TCO materials needs to increase electron mobility as much as possible and reduce carrier concentration as much as possible. Summary of the invention

[0003] In order to overcome the deficiencies of the prior art, one of the purposes of the present invention is to provide a metal oxide transparent conductive film, which can effectively control the oxygen vacancy concentration in the In2O3 film by utilizing the fact that the rare earth ions in the rare earth oxide have lower electronegativity and the ionic bond Ln-O formed with the oxygen ions has higher bond breaking energy. In addition, the rare earth metal ions and indium ions have comparable ionic radii, which makes it easier to maintain the crystalline structure of indium oxide during doping, ensuring that the 5s orbital of indium fully overlaps, and reducing the defect scattering caused by structural mismatch, thereby better maintaining its high mobility characteristics.

[0004] A second object of the present invention is to provide applications of the metal oxide transparent conductive film.

[0005] One of the purposes of the present invention is achieved by the following technical solution:

[0006] A metal oxide transparent conductive film, the metal oxide is: a small amount of rare earth oxide ReO is doped into the indium-containing metal oxide MO-In2O3 as a photogenerated carrier conversion center to form (In2O3) x (MO) y (ReO)z A transparent conductive material, wherein x+y+z=1, 0.8≤x<0.9999, 0≤y<0.2, 0.0001≤z≤0.1.

[0007] The rare earth oxide ReO is one of ytterbium oxide, europium oxide, cerium oxide, praseodymium oxide, and terbium oxide, or a combination of any two or more of the above.

[0008] In the metal oxide MO, M is one of Sn (tin), Bi (bismuth), Ti (titanium), Zr (zirconium), Hf (hafnium), Ta (tantalum), W (tungsten), Nb (niobium), and Mo (molybdenum), or a combination of any two or more materials. That is, the metal oxide transparent conductive film provided by the present invention is a composite conductive film based on indium oxide, which obtains a higher mobility and controls its carrier concentration by introducing rare earth oxides. Since the rare earth ions in the rare earth oxides have lower electronegativity, and the ionic bonds Ln-O formed with oxygen ions have higher bond breaking energy. Therefore, the oxygen vacancy concentration in the In2O3 film can be effectively controlled. The optional materials of the rare earth oxide ReO are one of ytterbium oxide, europium oxide, cerium oxide, praseodymium oxide, and terbium oxide, or a combination of any two or more materials, as a carrier concentration controller. Among them, Yb in ytterbium oxide and europium oxide 2+ Ions and Eu 2+ The ions have fully filled and half-filled 4f electron orbitals, respectively. Therefore, their divalent ions have lower energy in oxides than trivalent ions. At the same time, since the bond breaking enthalpy changes (ΔHf298) of Yb-O and Eu-O are 715.1 kJ / mol and 557.0 kJ / mol, respectively, which are much larger than the bond breaking energy of In-O, the oxygen vacancy concentration can be effectively controlled. The oxygen ions in cerium oxide, praseodymium oxide, and terbium oxide have the possibility of changing to +3 and +4 valences. In oxide semiconductors, for In 3+ When ions are replaced by doping, the carrier concentration can be significantly reduced. The bond breaking energy of Ce-O, Pr-O, and Tb-O bonds is higher, all greater than 759 kJ / mol. Therefore, cerium oxide, praseodymium oxide, and terbium oxide have stronger control over carrier concentration. Combined with the above characteristics, the introduction of ReO can effectively control the oxygen vacancies of oxide semiconductor films in high In systems. In addition, indium oxide is prone to lattice distortion during the preparation process, and the incorporation of rare earth oxides can be effectively suppressed; moreover, rare earth metal ions and indium ions have comparable ionic radii, and it is easier to maintain the crystalline structure of indium oxide during doping, ensuring that the 5s orbitals of indium are fully overlapped, which can reduce defect scattering caused by structural mismatch, and therefore can better maintain its high mobility characteristics.

[0009] At the same time, the introduction of ReO rare earth oxide can be used as a photogenerated charge conversion center. The material selection utilizes the characteristics of the 4f orbital electronic structure in rare earth ions, which can form an efficient charge conversion center with the 5s orbital of indium ions. Under positive bias, rare earth ions are in a stable low-energy state. Due to the modulation of the Fermi level, the film has a higher carrier concentration, which can effectively shield the carrier scattering effect caused by the conversion center, thereby having no significant effect on the electrical properties of the device. Under negative bias, the electronic orbital in the rare earth element 4f and the 5s orbital of indium are coupled, and the rare earth ion is in an unstable activated state. Through its coupled orbit, the photogenerated carrier returns to the "ground state" in the form of non-radiative transition; at the same time, the activation center is in an activated state again. Therefore, the conversion center can provide a fast recombination channel for photogenerated carriers to avoid their influence on the stability of the film.

[0010] Furthermore, the metal oxide transparent conductive film has a pyrophyllite crystal structure.

[0011] Preferably, 0.0001≤z≤0.005.

[0012] More preferably, 0.0009≤z≤0.001.

[0013] Furthermore, the carrier mobility of the metal oxide transparent conductive film is 50 to 200 cm 2 / Vs, the carrier concentration is 1×10 19 ~5×10 21 cm -3 Preferably, the carrier mobility of the metal oxide transparent conductive film is 120 to 200 cm 2 / Vs, the carrier concentration is 1×10 19 ~6×10 20 cm -3 .

[0014] Furthermore, the metal oxide transparent conductive film is prepared by adopting any one of physical vapor deposition process, chemical vapor deposition process, atomic layer deposition process, laser deposition process, reactive plasma deposition process and solution method process.

[0015] The second object of the present invention is achieved by adopting the following technical solution:

[0016] An application of the above-mentioned metal oxide transparent conductive film in solar cells, display panels or detectors.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention adopts a doping strategy to control the carrier concentration and improve the mobility by introducing rare earth oxide materials into indium-based metal oxides. The rare earth ions in the rare earth oxides have lower electronegativity and the ionic bonds Ln-O formed with oxygen ions have higher bond breaking energy, so the oxygen vacancy concentration in the In2O3 film can be effectively controlled. In addition, the rare earth ions and indium ions have comparable ionic radii, which can reduce defect scattering caused by structural mismatch, and thus better maintain its high mobility characteristics.

[0019] The present invention forms a high-performance transparent conductive film by introducing doped rare earth oxides into indium-containing metal oxides. Since the rare earth oxides have extremely high oxygen bond breaking energy, the carrier concentration in the oxide semiconductor can be effectively controlled, and the transmittance in the infrared band can be improved, making it more suitable for application in solar cells, display panels or detectors. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is the transmittance spectrum of TCO1 of the transparent conductive film in Example 6;

[0021] Figure 2 This is the transmittance spectrum of TCO2 of the transparent conductive film in Example 6. DETAILED DESCRIPTION

[0022] The present invention is further described below in conjunction with the accompanying drawings and specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0023] The following are specific embodiments of the present invention. Unless otherwise specified, the raw materials, equipment, etc. used in the following embodiments can be obtained by purchase.

[0024] Example 1: Cerium oxide doped indium tin oxide transparent conductive film

[0025] A group of metal oxide transparent conductive films, the material of which is: cerium oxide is doped into indium tin oxide (ITO) as a charge conversion center to form a transparent conductive material of cerium oxide doped indium tin zinc oxide (Ce:ITO). The group of metal oxide transparent conductive films is prepared by a solution method.

[0026] Among them, for the oxide ratio formula (InO 1.5 ) x (MO) y (ReO) z , MO is SnO2, ReO oxide is CeO2. The oxide (InO 1.5 ) x (SnO2)y (CeO2) z In the figure, x=0.97270, y=0.0264, z=0.0009. However, the above ratio is not limited thereto. In some other embodiments, x=0.96000, y=0.03908, z=0.00092, or x=0.900, y=0.095, z=0.0050, or x=0.9200, y=0.07999, z=0.00001 are not described in detail here.

[0027] The carrier mobility of the metal oxide transparent conductive film is 123cm 2 / Vs, the carrier concentration is 9.1×10 19 cm -3 .

[0028] Example 2: Ytterbium oxide doped indium titanium oxide transparent conductive film

[0029] A group of metal oxide transparent conductive films, the material of which is: Ytterbium oxide is doped into indium titanium oxide (ITiO) as a charge conversion center to form a transparent conductive material of ytterbium oxide doped indium titanium oxide (Yb:ITiO). The group of metal oxide transparent conductive films is prepared by magnetron sputtering.

[0030] Among them, for the oxide ratio formula (InO 1.5 ) x (MO) y (ReO) z , MO is TiO2, ReO oxide is Yb2O3. The oxide (InO 1.5 ) x (TiO2) y (YbO 1.5 ) z In the example, x=0.97943, y=0.01959, and z=0.00098. However, the above ratios are not limited thereto. In some other embodiments, x=0.98000, y=0.01950, and z=0.00050, or x=0.99000, y=0.00500, and z=0.00500, or x=0.9200, y=0.07999, and z=0.00001 are not described in detail here.

[0031] The carrier mobility of the metal oxide transparent conductive film is 186 cm 2 / Vs, the carrier concentration is 3.6×10 20 cm -3 .

[0032] Example 3: Europium oxide doped indium zirconium oxide transparent conductive film

[0033] A group of metal oxide transparent conductive films, the material of which is: europium oxide is doped into indium zirconium oxide (IZrO) as a charge conversion center to form a transparent conductive material of europium oxide doped indium zirconium oxide (Eu:IZrO). The group of metal oxide transparent conductive films is prepared by atomic layer deposition method.

[0034] Among them, for the oxide ratio formula (InO 1.5 ) x (MO) y (ReO) z , MO is ZrO2, ReO oxide is Eu2O3. The oxide (InO 1.5 ) x (ZrO2) y (EuO 1.5 ) z In the figure, x=0.93943, y=0.05959, z=0.00098. However, the above ratio is not limited thereto. In some other embodiments, x=0.98000, y=0.01950, z=0.00050, or x=0.97000, y=0.02800, z=0.00200, or x=0.9900, y=0.00999, z=0.00001, which will not be described in detail here.

[0035] The carrier mobility of the metal oxide transparent conductive film is 135cm 2 / Vs, the carrier concentration is 8.8×10 19 cm -3 .

[0036] Example 4: Praseodymium oxide doped indium oxide transparent conductive film

[0037] A group of metal oxide transparent conductive films, the material of which is: Ytterbium oxide is doped into indium oxide (In2O3) as a charge conversion center to form a transparent conductive material of ytterbium oxide doped indium oxide (IPrO). The group of metal oxide transparent conductive films is prepared by a reactive plasma deposition method.

[0038] Among them, for the oxide ratio formula (InO 1.5 ) x (MO) y (ReO) z , does not contain MO, that is, y = 0; ReO oxide is Pr2O3. The oxide (InO 1.5 ) x (PrO 1.5 ) zIn the above example, x=0.9000 and z=0.1000. However, the above ratio is not limited thereto. In some other embodiments, x=0.98000 and z=0.0200, or x=0.99000 and z=0.01000, or x=0.9990 and z=0.00100, which will not be described in detail here.

[0039] The carrier mobility of the metal oxide transparent conductive film is 173 cm 2 / Vs, the carrier concentration is 5.6×10 20 cm -3 .

[0040] Example 5: Terbium oxide doped indium oxide transparent conductive film

[0041] A group of metal oxide transparent conductive films, the material of which is: terbium oxide is doped into indium oxide (In2O3) as a charge conversion center to form a transparent conductive material of terbium oxide doped indium oxide (ITbO). The group of metal oxide transparent conductive films is prepared by magnetron sputtering.

[0042] Among them, for the oxide ratio formula (InO 1.5 ) x (MO) y (ReO) z , no MO; ReO oxide is Tb2O3. The oxide (InO 1.5 ) x (TbO 1.5 ) z In the figure, x=0.9800, y=0, z=0.0200; but not limited to the above ratio, in some other embodiments, x=0.9900, y=0, z=0.0100; or x=0.9850, z=0.0150, or x=0.9990, y=0, z=0.0010, which will not be repeated here.

[0043] The carrier mobility of the metal oxide transparent conductive film is 148 cm 2 / Vs, the carrier concentration is 9.4×10 19 cm -3 .

[0044] Example 6: Heterojunction Solar Cell

[0045] In this embodiment, an n-type single crystal silicon wafer is used as a substrate, and then an intrinsic a-Si and a p-type a-Si with a thickness of 10 nm are sequentially deposited on the n-type silicon wafer after a cleaning process to form a pn heterojunction, and then a transparent conductive film TCO1 is deposited on the pn heterojunction. An intrinsic a-Si film and an n-type a-Si film with a thickness of 10 nm are sequentially deposited on the back of the silicon wafer, and then a transparent conductive film TCO2 is deposited on the n-type a-Si film. Finally, conductive silver paste is prepared on TCO1 and TCO2 respectively using screen printing technology as a collector.

[0046] The TCO1 material is a transparent conductive material doped with ytterbium oxide and prepared by reactive plasma deposition. 1.5 ) x (YbO 1.5 ) z Where x=0.9000, z=0.1000.

[0047] The specific conditions for its preparation are as follows:

[0048] The target material is a cylindrical ceramic target with a relative density of about 65%;

[0049] The substrate is not heated, and a double-gun plasma source is used, that is, two targets are coated simultaneously;

[0050] The oxygen content in the cavity is 20%, that is, O2 / (Ar+O2)=20%;

[0051] The cavity pressure is 0.3Pa;

[0052] The voltage applied to the ion source was 70 V, 175 A;

[0053] The TCO2 material is a transparent conductive material doped with ytterbium oxide and prepared by magnetron sputtering deposition. 1.5 ) x (YbO 1.5 ) z Where x=0.98000, z=0.0200.

[0054] The specific conditions for its preparation are as follows:

[0055] The target material is a strip-shaped ceramic target with a relative density of about 99%. Single target sputtering coating is adopted.

[0056] The substrate is not heated;

[0057] The oxygen content in the cavity is 1.0%, that is, O2 / (Ar+O2)=1.0%;

[0058] The cavity pressure is 0.3Pa;

[0059] A pulsed DC power supply is used, and the sputtering power is 2kw;

[0060] At the same time, in this embodiment, we also prepared a reference film on a blank quartz substrate. The Hall properties of the prepared transparent conductive film are shown in Table 1, and the film transmittance spectrum is shown in Figure 1 and Figure 2 shown.

[0061] Table 1 Hall performance parameters of transparent conductive films

[0062] Material <![CDATA[Carrier concentration (cm -3 )]]> <![CDATA[Carrier mobility (cm 2 / Vs)]]> TCO1 <![CDATA[1.2×10 20 ]]> 169 TCO2 <![CDATA[1.5×10 20 ]]> 142

[0063] In the above embodiments, the transparent conductive film TCO1 and the transparent conductive film TCO2 are not limited to the materials mentioned above. The materials may also be composed of the transparent conductive films in the embodiments 1-5 described in the present invention, which will not be described in detail here.

[0064] Embodiment 7: Display panel

[0065] A display panel comprises the transparent conductive film in the above-mentioned embodiments 1-5, wherein the film is used as an anode of an organic light emitting diode (OLED) in the display panel.

[0066] Example 8: Detector

[0067] A detector comprises the transparent conductive film in the above-mentioned embodiments 1-5, wherein the film is used to drive a detection unit of the detector.

[0068] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A metal oxide transparent conductive film, characterized in that: The metal oxide is: a small amount of rare earth oxide ReO is doped into the indium-containing metal oxide MO-In2O3 as a photogenerated carrier conversion center to form a transparent conductive material of (In2O3)x(MO)y(ReO)z, wherein x+y+z=1, 0.8≤x<0.9999, 0≤y<0.2, 0.0001≤z≤0.1; The metal oxide transparent conductive film has a pyrophyllite crystal structure; The carrier mobility of the metal oxide transparent conductive film is 120 to 200 cm 2 / Vs, the carrier concentration is 1×10 19 ~6×10 20 cm -3 ; In the MO, M is one or a combination of any two or more materials selected from Sn, Bi, Ti, Zr, Hf, Ta, W, Nb, and Mo; The rare earth oxide ReO is one of ytterbium oxide, europium oxide, cerium oxide, praseodymium oxide, and terbium oxide, or a combination of any two or more of the above.

2. The metal oxide transparent conductive film according to claim 1, characterized in that: 0.0001≤z≤0.005。 3. The metal oxide transparent conductive film according to claim 2, characterized in that: 0.0009≤z≤0.001。 4. The metal oxide transparent conductive film according to claim 1, characterized in that: The metal oxide transparent conductive film is prepared by adopting any one of physical vapor deposition process, chemical vapor deposition process, atomic layer deposition process, laser deposition process, reactive plasma deposition process and solution method process.

5. Use of the metal oxide transparent conductive film according to any one of claims 1 to 4 in solar cells, display panels or detectors.

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