Ion-Blocking Thin Film Based on Metal Pseudohalides for Inorganic Light-Emitting Displays, and Method of Fabrication

Abstract

The present invention discloses an ion shielding film for an inorganic light-emitting display using a metal-like halide thin film and a method for manufacturing the same. According to the present invention, an electronic device is provided comprising a first functional layer between a first electrode and a second electrode, wherein the first functional layer is a photoactive layer or a dielectric layer, and the ion shielding film is composed of a metal-like halide disposed between the first electrode and the first functional layer, wherein the ion shielding film has a thickness of 30 to 50 nm, and the RMS roughness of the interface between the first electrode and the first functional layer is maintained at 1.0 nm or less by the formation of the ion shielding film.

Description

Technology Field

[0001] The present invention relates to the field of displays and electronic devices, and more specifically, to an ion shielding film and a method for manufacturing the same for suppressing device degradation and lifespan reduction caused by ion migration in inorganic light-emitting displays (e.g., Micro LED (μLED), Quantum Dot Display (QD-LED)). Background Technology

[0002] Inorganic light-emitting displays and quantum dot displays (QD-LEDs) offer the advantages of high brightness and high color purity, but ion migration between the light-emitting layer and the electrodes leads to problems such as reduced luminous efficiency, decreased color stability, and shortened operating lifespan.

[0003] In particular, when using low-work electrodes such as Ag and Al, the charge injection barrier increases and the number of interfacial defects (trap states) increases, resulting in leakage current and non-uniformity of luminescence.

[0004] To prevent this, various metal oxide thin films (V2O5, NiO, etc.) or polymer-based shielding films (PEDOT:PSS, etc.) have been studied; however, metal oxide thin films require high-temperature heat treatment, making them unsuitable for low-temperature process compatibility of light-emitting devices, while polymer shielding films such as PEDOT:PSS are vulnerable to moisture and oxygen, resulting in low long-term stability and limiting device performance due to issues with surface roughness and conductivity characteristics.

[0005] In addition, conventional Ag·Al-based electrodes have low charge collection efficiency due to their low work function (WF < 5.0 eV), and there is a serious problem with leakage current in devices such as MIM capacitors.

[0006] Furthermore, the low work function of the ITO electrode ( 4.7 eV) causes an energy level mismatch with the light-emitting layer, which lowers the charge injection efficiency and increases power consumption.

[0007] Accordingly, new high-work-function and high-stability ion shielding technology is required to realize high-efficiency and long-life devices. Prior art literature

[0008] US 2024 / 0273404 Al The problem to be solved

[0009] To solve the problems of the aforementioned prior art, the present invention proposes an ion shielding film for inorganic light-emitting displays using a metal-like halide thin film capable of effectively blocking ion movement and simultaneously improving charge injection efficiency and interface stability, as well as a method for manufacturing the same. means of solving the problem

[0010] In order to achieve the above-mentioned purpose, according to one embodiment of the present invention, an electronic device is provided comprising a first functional layer between a first electrode and a second electrode, wherein the first functional layer is a photoactive layer or a dielectric layer, and the ion shielding film is made of a metal-like halide disposed between the first electrode and the first functional layer, wherein the ion shielding film has a thickness of 30 to 50 nm, and the RMS roughness of the first electrode / first functional layer interface is maintained at 1.0 nm or less by the formation of the ion shielding film.

[0011] The above metal-like halide may include CuSCN (copper(I) thiocyanate).

[0012] The above-mentioned first electrode may be an ITO transparent electrode, and the above-mentioned first functional layer may be a photoactive layer, and may include an organic solar cell (OPV) structure.

[0013] The above OPV is composed of an ITO / CuSCN / PM6:Y6 / PDINO / Al stacked structure, and has an open-circuit voltage V under indoor illumination conditions. OC This is 680 mV or higher, and the FF (Fill Factor) may be 75% or higher.

[0014] The above-mentioned first electrode may include a metal-insulator-metal (MIM) capacitor structure (TiN / TiO2 / CuSCN / Ag) in which the first functional layer is a dielectric layer.

[0015] The above MIM capacitor has a leakage current density ≤0.20 μA / cm² at 2 V. 2 It can satisfy.

[0016] Due to the formation of the above ion shielding film, the effective work function of the first electrode can be increased to 5.3 eV or more.

[0017] According to another aspect of the present invention, a method for manufacturing an electronic device comprising a first functional layer between a first electrode and a second electrode is provided, comprising: (a) forming a first electrode on a substrate and pre-treating the surface of the first electrode by dry plasma treatment; (b) preparing a coating solution by dissolving and filtering a metal-like halide in an organic solvent; (c) forming a metal-like halide ion shielding film by spin-coating the solution onto the first electrode; (d) heat-treating the ion shielding film at 80 to 120°C for 5 to 20 minutes in an inert atmosphere; and (e) forming a first functional layer on the ion shielding film and stacking the second electrode to complete the electronic device; wherein the first functional layer is a photoactive layer or a dielectric layer, and the RMS roughness of the interface between the first electrode and the first functional layer is maintained at 1.0 nm or less by the formation of the ion shielding film. Effects of the invention

[0018] According to the present invention, the metal-like halide thin film forms a dense and uniform interface layer to suppress ion diffusion into the light-emitting layer, thereby significantly reducing the degradation rate of the device. Additionally, due to the high work function (about 5.35 eV) of the CuSCN-based thin film, the energy level alignment with the light-emitting layer is optimized, which lowers the charge injection barrier and enables efficient hole transport, thereby improving luminous efficiency and current-voltage characteristics.

[0019] In addition, defects and leakage paths at the metal electrode / emissive layer interface are reduced, allowing for leakage current characteristics that are about 200 times lower than those of conventional Ag electrode-based devices. Consequently, power consumption is reduced and luminescence uniformity is improved, and stability against moisture and oxygen is excellent, which significantly improves long-term operating characteristics compared to PEDOT:PSS-based devices, and for example, it can maintain more than 85% of the initial efficiency even after more than 500 hours of operation.

[0020] Furthermore, it can be applied without degradation of the device's brightness and color reproduction rate by maintaining a visible light transmittance of over 90%, and since it can be fabricated using a low-temperature process, it is suitable for manufacturing flexible substrates and large-area displays, and can be widely utilized in various light-emitting displays such as QD-LED, μLED, and OLED, as well as other electronic devices such as OPV and MIM capacitors. Brief explanation of the drawing

[0021] Figure 1 is a diagram comparing the chemical / electronic / surface / optical properties of a PEDOT:PSS layer or a CuSCN layer formed on an ITO electrode. Figure 2 shows an OPV structure with the interface layer of the present invention applied, energy level alignment, and a comparison of device characteristics. Figure 3 compares the photoelectric characteristics and hole injection and transport behavior of an OPV with the HTL of the present invention applied. Figure 4 is a diagram comparing the optical behavior in PEDOT:PSS and CuSCN-based OPVs. Figure 5 shows the photocurrent density-effective voltage (J) of an organic solar cell under LED 1000 lx, FL 1000 lx, and HL 1000 lx irradiation conditions. ph -V eff ) represents the characteristics. Figure 6 shows an example of applying the metal-like-halogenated thin film of the present invention to a metal-insulator-metal (MIM) capacitor. Figure 7 shows the results of comparing the capacitance characteristics, thin film crystal phase, and leakage current characteristics of PEDOT:PSS and CuSCN-based MIM capacitors. Specific details for implementing the invention

[0022] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the invention to specific embodiments, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0023] Furthermore, the components of the embodiments described with reference to each drawing are not limited to the respective embodiments and may be implemented to be included in other embodiments within the scope of maintaining the technical spirit of the present invention. It is also obvious that multiple embodiments may be re-implemented as a single embodiment that integrates multiple embodiments, even if a separate description is omitted.

[0024] Furthermore, in the description referring to the attached drawings, identical components are assigned the same or related reference numerals regardless of drawing symbols, and redundant descriptions thereof are omitted. In describing the present invention, if it is determined that a detailed description of related prior art could unnecessarily obscure the essence of the present invention, such detailed description is omitted.

[0026] The present invention relates to a technology for improving the work function of an electrode and achieving ion shielding and leakage current suppression by introducing a metal-like halide thin film (e.g., CuSCN) at the electrode interface.

[0027] According to the present invention, a method for manufacturing an electronic device comprising a first functional layer between a first electrode and a second electrode is provided, comprising the steps of: (a) forming a first electrode on a substrate and pre-treating the surface of the first electrode by dry plasma treatment; (b) preparing a coating solution by dissolving and filtering a metal-like halide in an organic solvent; (c) forming a metal-like halide ion shielding film by spin-coating the solution onto the first electrode; (d) heat-treating the ion shielding film at 80 to 120°C for 5 to 20 minutes in an inert atmosphere; and (e) forming a first functional layer (photoactive layer or dielectric layer) on the ion shielding film and stacking the second electrode to complete the electronic device.

[0028] Here, the first functional layer is a photoactive layer or a dielectric layer; if it is a photoactive layer, the electronic device is an indoor organic photovoltaic (OPV), and if it is a dielectric layer, the electronic device may be a metal-insulator-metal (MIM) capacitor.

[0029] Recent studies have reported that introducing metal-like halides can significantly enhance the work function of electrodes, thereby improving charge transport and interface alignment. In particular, CuSCN-based thin films have been shown to significantly improve the performance of OPVs and MIM capacitors by exhibiting transparency exceeding 90%, a wide bandgap exceeding 3.5 eV, and a high work function of approximately 5.35 eV. Therefore, implementing these as ultrathin shielding layers can achieve suppression of ion migration, improved charge injection uniformity, and increased lifetime in electronic devices, including inorganic light-emitting displays.

[0030] The optimal embodiment of the present invention achieves high efficiency and long lifespan of OPV and MIM capacitor devices by introducing a CuSCN layer with a thickness of 30-50 nm on an ITO electrode, wherein, in particular, CuSCN exhibits a higher work function (5.35 eV vs. 5.15 eV) and a lower leakage current (0.17 μA / cm²) compared to PEDOT:PSS. 2 to 0.28 μA / cm 2 It demonstrates a distinct performance advantage by providing higher power conversion efficiency (PCE, 30.1% vs. 27.2%).

[0031] The interface structure and performance according to the present embodiment will be described in detail below with reference to the drawings.

[0032] Figure 1 is a diagram comparing the chemical / electronic / surface / optical properties of a PEDOT:PSS layer or a CuSCN layer formed on an ITO electrode.

[0033] Figure 1a illustrates the schematic structure of PEDOT:PSS and metal-like halide CuSCN as a hole transport layer (HTL), and the concept of them being coated on ITO to form an interface.

[0034] Figure 1b is a UPS spectrum showing that the work function (Φ) increases in the order of ITO (lower curve), ITO / PEDOT:PSS (middle), and ITO / CuSCN (top), and Figure 1c is a ΔWF bar graph showing that PEDOT:PSS shows an increase in work function of about +0.41 eV and CuSCN shows an increase of about +0.61 eV compared to ITO.

[0035] Figure 1(d) is an AFM 3D surface image showing that interface planarization is achieved as the RMS roughness decreases from 1.223 nm for ITO to 0.918 nm for PEDOT:PSS and 0.905 nm for CuSCN, and Figure 1e is an optical transmittance spectrum showing that ITO alone, ITO / PEDOT:PSS, and ITO / CuSCN all maintain high transmittance in the visible light region.

[0036] From the results of Figure 1, it can be seen that the CuSCN layer provides a larger work function and excellent interfacial planarization while maintaining high transparency.

[0037] Figure 2 shows an OPV structure with the interface layer of the present invention applied, energy level alignment, and a comparison of device characteristics.

[0038] Figure 2a shows the absorption spectra of photoactive layer materials PM6, Y6 and a mixture thereof (PM6:Y6).

[0039] Figure 2b is an energy level diagram, showing the Φ of ITO 4.74 eV, Φ of ITO / PEDOT:PSS Φ of ITO / CuSCN at 5.15 eV It shows 5.35 eV, and the HOMO of PM6 ( The alignment relationship between Y6's LUMO, PDINO, and Al electrodes is plotted together (5.45 eV). It can be seen that the hole injection barrier is minimized when CuSCN is applied.

[0040] Figure 2c is a cross-sectional scanning electron microscope (SEM) image showing a stacked structure of ITO (150 nm) / HTL (40 nm, PEDOT:PSS or CuSCN) / PM6:Y6 (160 nm) / PDINO (10 nm) / Al (150 nm).

[0041] Figure 2(d) compares the current-voltage (JV) characteristics under various illuminance conditions (e.g., LED 1000 lx, HL 1000 lx, FL 1000 lx), showing that the CuSCN-based OPV has a higher V compared to the PEDOT:PSS-based OPV. OC and indicates that FF is shown.

[0042] FIG. 2e shows the parasitic resistance parameter (series r s , parallel r p This compares the series resistance r when CuSCN is applied. s Reduction and parallel resistance r pIt shows an increasing trend, suggesting a reduction in injection / transport losses and leakage suppression.

[0043] Figure 3 compares the photoelectric characteristics and hole injection and transport behavior of an OPV with the HTL of the present invention applied.

[0044] Figure 3a shows the output power density under conditions of LED 1000 lx (2700 K), LED 1000 lx (5200 K), FL 1000 lx, and HL 1000 lx, and the CuSCN-based device exhibits a higher output power density under full illuminance conditions compared to the PEDOT:PSS-based device.

[0045] Figure 3b shows the external quantum efficiency (EQE) spectra of PEDOT:PSS and CuSCN-based OPVs at representative wavelengths. Both devices exhibit similar responses across the entire visible light range, but it can be seen that when CuSCN is applied, the integral response in the active wavelength range is maintained or slightly improved.

[0046] Figure 3c shows the photon flux density spectrum and wavelength dependence of each light source.

[0047] Figure 3d shows the current-voltage (JV) curve under dark conditions for trap density analysis.

[0048] Figure 4 is a diagram comparing the optical behavior in PEDOT:PSS and CuSCN-based OPVs.

[0049] Figure 4a illustrates the power absorption profile obtained by FDTD-based calculation, showing that when CuSCN is applied as an HTL, the effective absorption in the active layer region is maintained and increased.

[0050] Figure 4b shows the refractive index of each layer (ITO, PM6:Y6, PDINO, Al, PEDOT:PSS, CuSCN). and extinction coefficient The spectrum is presented to demonstrate that high transmittance and appropriate optical constants are maintained even when CuSCN is applied.

[0051] Figure 5 shows the photocurrent density-effective voltage (J) of an organic solar cell under LED 1000 lx, FL 1000 lx, and HL 1000 lx irradiation conditions. ph -V eff ) represents the characteristics.

[0052] Referring to Fig. 5, the photocurrent density-effective voltage of the CuSCN-based device was measured under LED 1000 lx (2700 K, 5200 K), HL 1000 lx, and FL 1000 lx conditions, and the CuSCN-based device showed a higher open-circuit voltage compared to the PEDOT:PSS-based device. V OC It shows (approx. 698 mV) and FF (approx. 79.1%), and as a result, PCE is approximately 30.1%, showing a relative improvement of about 11% compared to PEDOT:PSS based (approx. 27.2%).

[0053] Figure 6 shows an example of applying the metal-like-halogenated thin film of the present invention to a metal-insulator-metal (MIM) capacitor.

[0054] Figure 6a is an energy band diagram illustrating the formation of a barrier on the side of hole injection in a TiN / TiO2 / HTL / Ag stack, showing that when CuSCN is applied as HTL, a larger electric field barrier is formed compared to PEDOT:PSS, which is advantageous for suppressing leakage.

[0055] In the cross-sectional scanning electron microscope (SEM) image of Fig. 6b, a stacked structure consisting of a bottom TiN (approx. 20 nm), TiO2 (approx. 20 nm), HTL (PEDOT:PSS or CuSCN), and a top Ag (approx. 40–45 nm) is confirmed. In this structure, the device with CuSCN applied as the HTL exhibits a leakage current density of 0.17 μA / cm² at -2 V. 2 Representing the Ag electrode reference structure (40.12 μA / cm²) 2It exhibits leakage current characteristics approximately 235 times lower than that of PEDOT:PSS. This demonstrates that CuSCN thin films more effectively enhance ion shielding ability and interfacial electric field barriers compared to PEDOT:PSS.

[0056] Figure 7 shows the results of comparing the capacitance characteristics, thin film crystal phase, and leakage current characteristics of PEDOT:PSS and CuSCN-based MIM capacitors.

[0057] Figure 7a shows the capacitance-voltage (CV) curve at 1 kHz, and all three structures (TiO2 alone, TiO2 / PEDOT:PSS, and TiO2 / CuSCN) exhibit relatively flat capacitance retention characteristics with respect to voltage change, and stable behavior without capacitance degradation is confirmed when CuSCN is applied.

[0058] The capacitance density bar graph in Fig. 7b shows values ​​measured at the same frequency (1 kHz), and it can be seen that the TiO2 / CuSCN structure exhibits improved capacitance density compared to TiO2 / PEDOT:PSS.

[0059] Referring to the XRD pattern of the TiO2 thin film in Fig. 7c, it can be seen that the main crystalline phase of TiO2 is preserved by the introduction of CuSCN.

[0060] The current density-voltage (JV) characteristics in Fig. 7d compare the leakage current behavior, and the TiO2 / CuSCN structure shows the lowest current density across the entire region, indicating that leakage current is significantly suppressed (arrow area).

[0062] Hereinafter, the process of manufacturing an ion shielding film for an inorganic light-emitting display according to the present embodiment is described in detail.

[0063] A. Preparation of materials

[0064] CuSCN is used from Sigma-Aldrich, dissolved in diethyl sulfide solvent at 15 mg / mL, and then filtered through a 0.45 μm PTFE filter. PEDOT:PSS (AI4083) is used from Meryer Chemical Technology after being filtered through a 0.45 μm PVDF filter. Other device materials used include PM6, Y6, PDINO, TiN, TiO2 (ALD grown), Ag, and Al.

[0065] B. Electrode / Interfacial Layer Fabrication (CuSCN vs PEDOT:PSS)

[0066] The ITO substrate is ultrasonically cleaned for 15 minutes each in the order of DI water + detergent → acetone → IPA, and then surface treated with O2 plasma (150 W, 2 min). The CuSCN layer is spin-coated with a 15 mg / mL solution (3000 rpm, 30 sec) and then annealed at 100 °C in an N2 atmosphere for 10 minutes. The PEDOT:PSS layer is spin-coated (5000 rpm, 60 sec) and then annealed at 150 °C for 10 minutes. UPS analysis confirms that the WF of ITO is 4.74 eV, 5.15 eV after PEDOT:PSS treatment, and 5.35 eV after CuSCN treatment; AFM analysis confirms interfacial planarization with RMS roughness values ​​of 1.223 nm for ITO, 0.918 nm for PEDOT:PSS, and 0.905 nm for CuSCN.

[0067] C. Examples

[0068] Example 1: CuSCN-based indoor OPV

[0069] The device structure is ITO / CuSCN (40 nm) / PM6:Y6 (1:1.2) / PDINO / Al (150 nm). A PM6:Y6 solution (16 mg / mL, 0.5 wt% chloronaphthalene added) was spin-coated (3000 rpm, 30 sec) followed by annealing at 90 °C for 10 minutes. Under indoor lighting conditions (LED 1000 lx, 2700 K), the PCE was 30.1%, J_SC 158.1 μA / cm², and V when CuSCN was applied compared to PEDOT:PSS. OC It exhibits 698 mV and FF 79.1%, and PCE improves from 27.2% to 30.1% compared to PEDOT:PSS-based. This is attributed to the high WF of CuSCN improving alignment with the HOMO (5.45 eV) of PM6, thereby enhancing hole injection and FF.

[0070] Example 2: CuSCN-based MIM capacitor

[0071] The device structure consists of TiN (bottom electrode) / TiO2 (20 nm, ALD) / CuSCN (intermediate layer, 40 nm) / Ag (top electrode, 50 nm), and comparative structures include configurations with PEDOT:PSS or without an intermediate layer. At -2 V, the leakage current density of the reference Ag electrode was measured to be 40.12 μA / cm², 0.28 μA / cm² with PEDOT:PSS, and 0.17 μA / cm² with CuSCN, representing a decrease of approximately 235 times compared to the reference. This is because the electric field barrier is strengthened by high WF and flat interfaces, thereby suppressing Fowler-Nordheim tunneling.

[0072] D. Variations

[0073] In terms of materials, compounds based on AgSCN, Zn(SCN)2, and Fe(CN)6, in addition to CuSCN, can be applied, and MoO2 can be used instead of PEDOT:PSS as a comparison layer. x , NiO xInorganic oxides such as those mentioned above can be used. The thickness can be controlled within the range of 3 to 30 nm; in OPVs, it can be made thin to maintain transparency, while in MIMs, it can be made somewhat thicker to enhance leakage suppression. The structure can be expanded to various electrode combinations, such as ITO / CuSCN / perovskite / PCBM / Ag for OPVs and TiN / TiO2 / CuSCN / Ru for MIMs. Application fields can be extended to display devices such as μLEDs, QD-LEDs, and OLEDs, as well as energy storage capacitors, sensors, and transparent electrode devices.

[0074] The embodiments of the present invention described above are disclosed for illustrative purposes only, and those skilled in the art with ordinary knowledge of the present invention may make various modifications, changes, and additions within the spirit and scope of the present invention, and such modifications, changes, and additions should be considered to fall within the scope of the following claims.

Claims

Claim 1 An electronic device comprising a first functional layer between a first electrode and a second electrode, wherein the first functional layer is a photoactive layer or a dielectric layer, and comprises an ion shielding film made of a metal-like halide disposed between the first electrode and the first functional layer, wherein the ion shielding film has a thickness of 30 to 50 nm and the RMS roughness of the first electrode / first functional layer interface is maintained at 1.0 nm or less by the formation of the ion shielding film, and wherein the first electrode is TiN and the first functional layer is a dielectric layer, the electronic device is characterized by comprising a metal-insulator-metal (MIM) capacitor structure (TiN / TiO2 / CuSCN / Ag). Claim 2 An electronic device according to claim 1, characterized in that the metal-like halide comprises CuSCN (copper(I) thiocyanate). Claim 3 An electronic device according to claim 1, characterized in that the first electrode is an ITO transparent electrode and the first functional layer is a photoactive layer, comprising an organic photovoltaic (OPV) structure. Claim 4 An electronic device according to claim 3, wherein the OPV is composed of an ITO / CuSCN / PM6:Y6 / PDINO / Al stacked structure, and has an open-circuit voltage VOC of 680 mV or higher and a Fill Factor (FF) of 75% or higher under indoor illumination conditions. Claim 5 delete Claim 6 In claim 1, the MIM capacitor has a leakage current density ≤0.20 μA / cm² at -2 V. 2 An electronic device characterized by satisfying [ ]. Claim 7 An electronic device according to claim 1, characterized in that the effective work function of the first electrode increases to 5.3 eV or more due to the formation of the ion shielding film. Claim 8 A method for manufacturing an electronic device comprising a first functional layer between a first electrode and a second electrode, comprising: (a) forming a first electrode on a substrate and pre-treating the surface of the first electrode by dry plasma treatment; (b) preparing a coating solution by dissolving and filtering a metal-like halide in an organic solvent; (c) forming a metal-like halide ion shielding film by spin-coating the solution onto the first electrode; (d) heat-treating the ion shielding film at 80 to 120 ℃ for 5 to 20 minutes in an inert atmosphere; and (e) forming a first functional layer (photoactive layer or dielectric layer) on the ion shielding film and stacking the second electrode to complete the electronic device; wherein the first functional layer is a photoactive layer or a dielectric layer, and the RMS roughness of the interface between the first electrode and the first functional layer is maintained at 1.0 nm or less by the formation of the ion shielding film, the first electrode is TiN, and the first functional layer is a dielectric layer. A method for manufacturing an electronic device characterized by including a metal-insulator-metal (MIM) capacitor structure (TiN / TiO2 / CuSCN / Ag).

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