Transparent photoelectric film and preparation method and application thereof

Abstract

The invention provides a transparent photoelectric film and a preparation method and application thereof, the transparent photoelectric film is a composite layer with a heterostructure formed by a wide bandgap semiconductor layer and a copper-based halide layer which are mutually laminated, the band gap Eg of the wide bandgap semiconductor layer is greater than or equal to 3eV, the copper-based halide layer comprises CsmCynXm + n: RE, x comprises any one or a combination of at least two of Cl, Br or I, RE comprises any one or a combination of at least two of rare earth metals, m is greater than or equal to 1 and less than or equal to 3, and n is greater than or equal to 1 and less than or equal to 2. The photoelectric film provided by the invention gives consideration to transparency, functionality and structural adjustability in material design, and the provided preparation method realizes regional controllable growth and accurate thickness regulation of the film structure, and significantly improves the compactness, uniformity and optical performance of the film. And an effective support is provided for a high-performance patterned transparent photoelectric device.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of semiconductor materials and optoelectronic devices, and relates to a transparent optoelectronic film and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of information technology, energy conversion and optoelectronic industry, the application demand of optoelectronic devices in the fields of optical communication, ultraviolet detection, environmental monitoring and transparent display is increasing. Traditional optoelectronic devices are mostly opaque structures, which limits their integrated application in building facades, greenhouse agriculture, vehicle-mounted systems and mobile terminals. Therefore, the development of all-transparent optoelectronic devices with both photoelectric function and high visible light transmittance has become a research hotspot.

[0003] In the past few years, wide-bandgap semiconductor materials have attracted widespread attention due to their wide band gap, short ultraviolet cutoff wavelength and extremely low absorption in the visible light region, which exhibit excellent high transmittance characteristics. However, single-component wide-bandgap materials usually have problems such as large dark current and limited carrier mobility, which limit their application in high-response-speed and high-sensitivity detectors. On the other hand, copper-based halides, as a class of lead-free low-dimensional perovskite derivatives, have a direct band gap of more than 4 eV, with an absorption edge at 300 nm, exhibiting high excited-state binding energy, self-trapped exciton luminescence characteristics, high photoluminescence quantum efficiency (PLQY), large Stokes shift and wide emission spectrum. The energy band structure and luminescence performance can be finely adjusted by component regulation, showing potential in the fields of ultraviolet detection and visible light emitting devices.

[0004] However, the current preparation of copper-based halide optoelectronic films mainly relies on solution methods or quantum dot spin coating and other wet processes. Such methods generally have the following key technical defects: 1. Limited transparency. Organic solvents and surface ligands are easily left over during the wet preparation process, resulting in a decrease in the visible light transmittance of the film, which is difficult to meet the strict requirements of all-transparent optoelectronic devices for high light transmittance. 2. Non-uniform crystallization and uncontrolled morphology. The film formation process in the solution method is highly sensitive to temperature, evaporation rate and solvent environment, which easily leads to non-uniform crystallization and rough morphology of the film, forming defects such as pinholes and island structures, which seriously affect the photoelectric performance and device consistency. 3. Difficult to accurately control the area deposition. Traditional spin coating and other processes are mostly whole-body deposition, which lacks spatial selectivity and is difficult to meet the application requirements of patterning processing and multi-functional integration, especially limiting their application in high-resolution transparent detectors, white light LEDs and other complex structure devices. 4. Poor uniformity and repeatability in large area. The devices processed by wet process have poor stability in air and are significantly affected by environmental humidity and oxygen, which is difficult to serve for a long time.

[0005] Furthermore, copper-based halide materials still suffer from problems in applications such as severe nonradiative recombination, difficulty in bandgap modulation, and insufficient photostability. These issues lead to technical bottlenecks in currently prepared copper-based halide optoelectronic thin films regarding high transparency, morphology controllability, large-area uniform deposition, and device integration adaptability. Therefore, developing a copper-based halide composite optoelectronic thin film with high transparency, controllable morphology, and good stability is of great significance for promoting the development of fully transparent optoelectronic devices. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a transparent optoelectronic thin film, its preparation method, and its applications. The optoelectronic thin film provided by this invention balances transparency, functionality, and structural tunability in its material design. Furthermore, the provided preparation method enables regionally controllable growth and precise thickness control of the thin film structure, significantly improving its density, uniformity, and optical properties, thus providing effective support for high-performance, patternable transparent optoelectronic devices.

[0007] To achieve this objective, the present invention employs the following technical solution:

[0008] In a first aspect, the present invention provides a transparent optoelectronic thin film, wherein the transparent optoelectronic thin film is a composite layer with a heterogeneous structure formed by stacking a wide bandgap semiconductor layer and a copper-based halide layer, wherein the bandgap E of the wide bandgap semiconductor layer is... g ≥3eV, the copper-based halide layer includes Cs m Cu n X m+n RE, where X includes any one or at least two of Cl, Br or I, RE includes any one or at least two of rare earth metals, 1≤m≤3, 1≤n≤2.

[0009] For example, the band gap of a wide bandgap semiconductor layer is 3eV, 3.5eV, 4eV, 4.5eV or 5eV, m=1, 2 or 3, n=1 or 2, etc., but it is not limited to the listed values. Other unlisted values ​​within this range also apply.

[0010] In this invention, due to the difference in work function and band discontinuity between the wide-bandgap semiconductor and the copper-based halide material, a built-in electric field can be formed at the heterojunction interface. This helps to efficiently separate photogenerated carriers, reduce recombination losses, suppress dark current, and improve the device's response rate and detection sensitivity. Compared to single-material systems, heterostructures offer advantages in device stability, photoelectric conversion efficiency, and functional integration.

[0011] Furthermore, this heterostructure system possesses excellent doping compatibility and band structure tunability. By introducing rare earth elements or other impurity ions, the band gap, energy level arrangement, and interfacial carrier dynamics of the material can be precisely controlled, further expanding the application performance and functional integration of the device in fields such as photodetection and light-emitting display.

[0012] Furthermore, the present invention utilizes E g Wide bandgap semiconductors with a voltage of ≥3eV maintain extremely high transmittance in the visible light region, effectively suppressing background noise absorption and ensuring excellent optical performance even in a fully transparent state. Simultaneously, wide bandgap semiconductors possess high breakdown electric field strength and excellent thermal stability, enabling heterostructures to operate stably under high voltage, high temperature, and strong radiation environments, significantly improving the device's environmental adaptability and long-term reliability.

[0013] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0014] Preferably, the band gap of the wide bandgap semiconductor layer is 3eV to 5eV, such as 3eV, 3.2eV, 3.4eV, 3.5eV, 3.6eV, 3.8eV, 4eV, 4.2eV, 4.5eV, 4.8eV or 5eV, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0015] Preferably, the wide bandgap semiconductor layer comprises any one or a combination of at least two of ZnO, MgZnO, Ga2O3, GaN, or Yb2O3.

[0016] In this invention, ZnO, Ga2O3, GaN, MgZnO, or Yb2O3 are further preferred within the bandgap range (3~5 eV). These materials not only meet the common requirements of high transmittance and chemical stability, but also possess outstanding characteristics: ZnO has excellent electron mobility and a mature sputtering process foundation; Ga2O3 has an extremely high critical breakdown electric field, suitable for high-power optoelectronic applications; GaN combines high thermal conductivity with good interface matching characteristics, contributing to stable device operation; MgZnO can achieve continuous tunability of the bandgap by adjusting the component ratio, facilitating the coverage of transparent optoelectronic requirements in different wavelength bands; Yb2O3, as a rare earth oxide, not only has a wide intrinsic bandgap, but also provides unique advantages for bandgap modulation and photoluminescence enhancement. Based on the above characteristics, these semiconductor materials are superior to general wide bandgap oxides or nitrides in terms of bandgap tunability, interface matching, and process compatibility, making them more suitable as functional layer materials in the heterostructure of this invention, thereby achieving a comprehensive improvement in transparency, stability, and device performance.

[0017] Preferably, the atomic percentage of RE in the copper-based halide layer is 0.5 at.% to 4 at.%, such as 0.5 at.%, 0.6 at.%, 1.5 at.%, 2 at.%, 2.5 at.%, 3 at.%, 3.5 at.%, or 4 at.%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0018] In this invention, excessive doping of rare earth elements can have an adverse effect on the stability of the thin film. By controlling it within the above-mentioned preferred range, it is more beneficial to balance the photoelectric properties and stability of the thin film.

[0019] Preferably, the RE is any one or a combination of at least two of Eu, Ce, Tb, Sm or Dy, and more preferably Eu and / or Ce.

[0020] In this invention, by introducing rare-earth ion doping into copper-based halides, their band structure, excited-state stability, and emission spectral range can be adjusted. When Eu and / or Ce are selected, their 4f energy level has a good energy level matching relationship with the band gap position of copper-based halides, effectively providing radiative transition channels during carrier recombination, thereby enhancing the exciton radiative recombination rate and improving luminescence efficiency; simultaneously, Eu... 2+ Ce 3+ The introduction of plasma states can suppress the formation of shallow-level traps, reduce nonradiative recombination losses, and improve the optical stability of materials. Therefore, it exhibits better results compared to doping with other rare-earth metals, such as Eu. 2+ Ions can emit blue light directly through the 5d→4f allowed transition or emit light after receiving host-host STE energy, thereby improving the brightness, color purity, and spectral stability of blue LEDs; Ce 3+ Ions can provide nanosecond-level fast emission channels, which is beneficial for high-modulation-bandwidth LEDs or short-pulse driving. For broadband photodetectors, Eu... 2+ / Ce 3+ Doping can improve photoelectric response and signal-to-noise ratio through energy level introduction and energy transfer, while passivating non-radiative traps in the host and host cells; its actual effect on response spectrum extension needs to be verified by combining energy level matching and photoelectric measurements. In scintillator applications, Ce... 3+ It can provide high temporal resolution and fast emission, while Eu 2+ It can increase light output and adjust the emission wavelength.

[0021] Preferably, the thickness of the wide bandgap semiconductor layer is 60nm~600nm, such as 60nm, 100nm, 200nm, 300nm, 400nm, 500nm or 600nm, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0022] Preferably, the thickness of the copper-based halide layer is 30nm to 240nm, such as 30nm, 50nm, 80nm, 100nm, 130nm, 150nm, 180nm, 200nm or 240nm, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0023] In this invention, when the thickness of the copper-based halide layer is controlled within the above-mentioned preferred range, the light transmittance of the film can be further improved.

[0024] Preferably, the transmittance of the transparent optoelectronic film is ≥80%, such as 80%, 83%, 85%, 88%, 90%, 93% or 95%, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0025] In a second aspect, the present invention provides a method for preparing a transparent optoelectronic thin film as described in the first aspect, the method comprising: depositing a wide bandgap semiconductor layer on a substrate by radio frequency magnetron sputtering, then depositing a copper-based halide layer on the wide bandgap semiconductor layer by single-source thermal evaporation, and finally annealing.

[0026] This invention employs a fully dry process combining radio frequency magnetron sputtering and single-source thermal evaporation, replacing existing solution spin coating or complex dual-source evaporation methods. This eliminates cumbersome steps such as solution concentration control, injection rate adjustment, and spin coating annealing, reducing dependence on the preparation environment. Furthermore, compared to the potential problems of solvent residue, color contamination, and uneven crystallization in solution processes, the physical vapor deposition method used in this invention offers greater control over film transparency, thickness, and interface quality. Wide-bandgap semiconductor films are grown via radio frequency magnetron sputtering, with thickness precisely controlled by adjusting power and deposition time. Copper-based halide films are grown using a single-source thermal evaporation process, avoiding surface defects caused by solution residue. This results in uniform morphology, good coverage, high transmittance, and dense heterostructure films. Moreover, due to the mild process conditions and simple steps of this invention, it also has the potential to be compatible with novel platforms such as flexible substrates, making it suitable for the fabrication of large-area, high-quality optoelectronic devices. In addition, magnetron sputtering and thermal evaporation, as universal PVD methods, are easy to integrate into existing microelectronic and display device manufacturing processes, which is beneficial for the design and implementation of subsequent patterned or integrated devices.

[0027] Preferably, the radio frequency magnetron sputtering includes: placing the substrate in the vacuum chamber of the radio frequency magnetron sputtering equipment, fixing it on the heating stage, then installing a wide bandgap semiconductor target on the target gun of the radio frequency magnetron sputtering, adjusting the system parameters and starting the sputtering program.

[0028] It should be noted that short circuits in the target material should be avoided during installation to ensure proper ignition of the equipment. The substrate with the transparent wide-bandgap semiconductor thin film already deposited by magnetron deposition should be inverted and fixed on the substrate stage of the evaporation chamber to ensure that the saturated vapor can grow on the substrate surface.

[0029] Preferably, the substrate is cleaned before use.

[0030] Preferably, the cleaning process includes: ultrasonically cleaning the substrate in acetone, ethanol, and deionized water sequentially for 5 min to 15 min, such as 5 min, 8 min, 10 min, 12 min, or 15 min, but not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0031] Preferably, the substrate includes an ITO glass substrate, an FTO glass substrate, or a C-plane Al2O3 substrate.

[0032] Preferably, the size of the substrate is (8mm~12mm)×(8mm~12mm), such as 8mm×8mm, 9mm×9mm, 10mm×10mm, 11mm×11mm or 12mm×12mm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0033] Preferably, the radio frequency magnetron sputtering is single-target sputtering.

[0034] The wide bandgap semiconductor layer in this invention employs a single-target radio frequency magnetron sputtering method, which reduces the dependence on atmosphere and multi-source power control compared to metal-organic chemical vapor deposition (MOCVD) or dual-target sputtering methods.

[0035] Preferably, before the sputtering process begins, the air pressure in the vacuum chamber is adjusted to 10. -3 Pa or less, for example, 10 -3 Pa, 10 - 4 Pa or 10 -5 Pa, etc., but not limited to the listed values; other unlisted values ​​within this range also apply.

[0036] Preferably, the temperature of the heating table is 25℃~600℃, more preferably 80℃~150℃, such as 25℃, 50℃, 80℃, 100℃, 150℃, 200℃, 400℃ or 600℃, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0037] Preferably, the rotation speed of the heating table is 5 rpm to 20 rpm, such as 5 rpm, 8 rpm, 10 rpm, 12 rpm, 15 rpm, 18 rpm or 20 rpm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0038] Preferably, the distance between the substrate and the wide bandgap semiconductor target is 5cm to 12cm, such as 5cm, 7cm, 10cm or 12cm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0039] Preferably, the atmosphere of the sputtering process includes argon.

[0040] Preferably, the purity of the argon gas is ≥99.99%.

[0041] Preferably, the gas flow rate of the sputtering process is 40 sccm to 50 sccm, such as 40 sccm, 42 sccm, 45 sccm, 47 sccm or 50 sccm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0042] Preferably, the gas pressure of the sputtering process is 0.5Pa to 2.5Pa, such as 0.5Pa, 0.8Pa, 1Pa, 1.3Pa, 1.5Pa, 1.8Pa, 2Pa or 2.5Pa, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0043] Preferably, the power of the sputtering process is 90W to 200W, such as 90W, 100W, 120W, 150W, 170W or 200W, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0044] This invention controls the sputtering rate and thin film density by adjusting the radio frequency power, achieving the growth of a wide bandgap semiconductor layer with high uniformity and high transparency, and possessing good repeatability and controllability.

[0045] Preferably, the sputtering process includes pre-sputtering and formal sputtering.

[0046] Preferably, the pre-sputtering time is 10 min to 20 min, such as 10 min, 12 min, 15 min, 17 min or 20 min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0047] Understandably, pre-sputtering refers to turning on the RF power supply but not the baffle, in order to remove contaminants from the target surface.

[0048] Preferably, the formal sputtering time is 0.5h to 4h, such as 0.5h, 1h, 2h, 3h or 4h, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0049] In this invention, the film thickness can be precisely controlled by setting the sputtering time, which improves the flexibility of device structure design. The longer the sputtering time, the thicker the film will be. The optimal sputtering time is 2 hours.

[0050] Preferably, the single-source thermal evaporation method includes: depositing (CsX) a ) m (CuX) b ) n (REX) c ) t The mixture yields a copper-based halide precursor, which is then loaded into a tungsten boat within the thermal evaporation equipment chamber. The substrate with the deposited wide-bandgap semiconductor layer is inverted and mounted on the substrate stage of the thermal evaporation equipment. System parameters are adjusted, and the thermal evaporation process is started. a X b and X c Each can independently include any one of Cl, Br or I, 1≤m≤3, 1≤n≤2, 0<t≤0.5.

[0051] In this invention, the copper-based halide layer is deposited using single-source thermal evaporation, eliminating the need for complex solution preparation, spin coating, or annealing steps. The overall process parameters are well-defined, exhibiting good repeatability, and are suitable for standardized large-area deposition. By adjusting CsX... a CuX b and REX c The stoichiometric ratio can adjust the band gap of copper-based halides, enabling the modulation of different lattice structures and emission spectra. Furthermore, different stoichiometric ratios significantly affect the crystal structure, band positions, and excited-state luminescence behavior of the thin film, demonstrating considerable flexibility in modulation and potential for structural design.

[0052] Preferably, the mixing method includes grinding.

[0053] Preferably, the grinding process is carried out in the dark.

[0054] In this invention, light protection is to prevent moisture absorption.

[0055] Preferably, the grinding time is 10 min to 20 min, such as 10 min, 12 min, 15 min, 18 min or 20 min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0056] In this invention, grinding the raw materials for 10 to 20 minutes can ensure the uniformity of the precursor, thereby promoting the improvement of film quality and composition uniformity.

[0057] Preferably, before the single-source thermal evaporation begins, the vacuum level inside the thermal evaporation equipment cavity is adjusted to 1×10⁻⁶. -5 Pa ~ 1×10 -4 Pa, for example 1×10 --5 Pa, 3×10 --5 Pa, 5×10 -5 Pa, 8×10 -5 Pa or 1×10 -4 Pa, etc., but not limited to the listed values; other unlisted values ​​within this range also apply.

[0058] It should be noted that halides (especially iodine-containing halides and rare earth halides) are sensitive to residual gases. This can be addressed by reducing the vacuum level to 1×10⁻⁶. -5 Pa ~ 1×10 -4 Pa can minimize the decomposition of halides or the introduction of oxygen caused by oxygen / water vapor.

[0059] Preferably, the rotation speed of the substrate stage is 5 rpm to 20 rpm, such as 5 rpm, 8 rpm, 10 rpm, 15 rpm or 20 rpm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0060] Preferably, the distance between the tungsten boat and the substrate is 5cm to 12cm, such as 5cm, 8cm, 10cm or 12cm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0061] Preferably, the tungsten boat is heated by current gradient control.

[0062] Preferably, in the current gradient control, the current rise rate is 3A / min to 4A / min, such as 3A / min, 3.2A / min, 3.4A / min, 3.6A / min, 3.8A / min, or 4A / min, but it is not limited to the listed values; other unlisted values ​​within this range are also applicable. It should be noted that the current rise rate should not be too fast to avoid localized overheating leading to instantaneous splashing or evaporation of off-components.

[0063] Preferably, the cutoff current of the current gradient control is 32A~38A, such as 32A, 33A, 34A, 35A, 36A, 37A or 38A, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0064] Preferably, the baffle is opened to start hot vapor deposition after the saturated vapor pressure of the copper-based halide precursor has stabilized.

[0065] Preferably, the rate of the single-source thermal evaporation is 0.1 Å / s to 1 Å / s, such as 0.1 Å / s, 0.2 Å / s, 0.4 Å / s, 0.5 Å / s, 0.7 Å / s or 1 Å / s, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0066] Preferably, the single-source thermal evaporation time is 1 min to 30 min, more preferably 1 min to 5 min, such as 1 min, 2 min, 3 min, 4 min, 5 min, 8 min, 10 min, 15 min or 30 min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0067] In this invention, the correspondence between current and source temperature needs to be determined through measured calibration (current → source temperature curve). By controlling the cutoff current at 32A~38A, the corresponding source surface temperature is approximately 600~700°C (based on the initial saturated vapor pressure of the copper-based halide precursor). Since CsX can be achieved under these temperature conditions... a CuX b REX c This process achieves thorough co-evaporation and uniform deposition, avoiding decomposition and partial evaporation caused by excessively high temperatures, thus forming copper-based halide films with balanced composition and good grain orientation. The specific process window significantly improves the film's crystallinity and interfacial density, ensuring effective incorporation of rare earth ions into the crystal lattice. Compared to existing technologies relying on solution spin-coating or low-temperature evaporation, this invention achieves precise control of current and evaporation time for the deposition of CsX... a CuX b and REX cOptimization of the co-deposition process yields higher film uniformity and structural stability.

[0068] Preferably, the annealing temperature is 150℃~220℃, such as 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃ or 220℃, and the time is 0.5h~2h, such as 0.5h, 1h, 1.5h or 2h.

[0069] In this invention, excessively high annealing temperature or excessively long annealing time can lead to the decomposition / recrystallization of iodides.

[0070] It should be noted that annealing should be carried out in an inert atmosphere or low vacuum to avoid oxidation or halogen release.

[0071] Thirdly, the present invention also provides an application of the transparent optoelectronic thin film as described in the first aspect, the application including its application in transparent optoelectronic devices.

[0072] Preferably, the transparent optoelectronic device includes an ultraviolet light detector or a fully transparent light-emitting diode.

[0073] The optoelectronic thin film provided by this invention exhibits good interface band alignment and spectral matching, which facilitates the efficient separation and transport of photogenerated carriers, providing a material basis for improving device response rate and signal-to-noise ratio. Unlike existing technologies that focus on a single function (such as flexible devices or self-driven detectors), the heterostructure of this invention combines high transparency, good electrical rectification characteristics, and photoelectric response performance. It is not only suitable for ultraviolet detectors but can also be extended to various fully transparent optoelectronic devices such as transparent light-emitting diodes (LEDs), achieving high consistency, high adaptability, and scalability. This provides a feasible path and technical support for the development of a new generation of fully transparent, high-performance, and multifunctional integrated optoelectronic devices, and has promising application prospects.

[0074] Compared with the prior art, the present invention has the following beneficial effects:

[0075] The system of this invention has good doping compatibility. By introducing rare earth elements, it is possible to effectively control the band gap, band structure and interface energy level matching of the thin film, so as to meet the diverse requirements of different optoelectronic devices (such as ultraviolet detectors, transparent LEDs, integrated displays, etc.) for spectral response and functional performance. Furthermore, this invention combines magnetron sputtering and thermal vapor deposition processes to achieve device-level structural compactness, high transmittance and large-area uniform deposition control, which significantly improves the optical performance and interface quality of the thin film. Attached Figure Description

[0076] Figure 1 This is a flowchart of the preparation method provided in Example 1.

[0077] Figure 2 This is an SEM image of the photoelectric thin film provided in Example 1.

[0078] Figure 3 This is an SEM image of the photoelectric thin film provided in Example 1.

[0079] Figure 4 This is an EDS elemental distribution diagram of the photoelectric thin film provided in Example 1.

[0080] Figure 5 This is the EDS energy spectrum of the photoelectric thin film provided in Example 1.

[0081] Figure 6 This is a photoluminescence (PL) pattern of the photoelectric thin film provided in Example 1.

[0082] Figure 7 This is the transmission spectrum of the photoelectric thin film provided in Example 1. Detailed Implementation

[0083] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0084] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0085] Example 1

[0086] This embodiment provides a transparent optoelectronic thin film ZnO / Cs3Cu2I5:Eu heterojunction film, wherein the thickness of the ZnO film layer is 280 nm, the thickness of the Cs3Cu2I5:Eu film layer is 130 nm, and the doping amount of Eu in Cs3Cu2I5 is 1.62 at.%. The preparation method is as follows: Figure 1 As shown, the details are as follows:

[0087] (1) Substrate cleaning: The substrate with crystal orientation is <0001> The 10mm × 10mm Al2O3 substrate was sequentially ultrasonically cleaned with acetone, ethanol, and deionized water for 10 minutes each, then rinsed with flowing deionized water and dried with a nitrogen gun. Finally, it was placed on the sample stage of the magnetron sputtering vacuum chamber for deposition.

[0088] (2) Magnetron sputtering of ZnO thin film: ZnO is used as the target material, and radio frequency magnetron sputtering is used to deposit the thin film. Before the deposition begins, the pressure in the vacuum chamber is reduced to 10. -3 Pa, substrate stage temperature set to 100℃, substrate stage rotation speed set to 10rpm, substrate to target distance set to 7cm, deposition atmosphere set to argon, gas flow rate set to 50sccm, gas pressure set to 1.5Pa, RF power supply set to 120W, pre-sputtering for 15min followed by formal deposition for 2h.

[0089] (3) Pretreatment of copper-based halides: Weigh CsI, CuI and EuI2 in a glove box with a molar ratio of 3:1:0.25, where CsI is 1.559g, CuI is 0.381g and EuI2 is 0.202g. Place the weighed drugs in a mortar and grind for 15min to obtain precursor powder.

[0090] (4) Transfer substrate: The substrate that has completed magnetron deposition is inverted and installed on the substrate fixing stage of the thermal evaporation equipment to ensure that copper-based halide vapor can be evenly covered on the substrate surface during the evaporation process.

[0091] (5) Evaporation of Cs3Cu2I5:Eu thin film layer: Cs3Cu2I5 layer was deposited by single-source evaporation. 0.2g of uniformly mixed precursor powder was weighed and placed in a tungsten boat. Before starting the evaporation, the vacuum degree was first evaporated to 10. --4 Below Pa, the current was turned on and the temperature was increased at a rate of 3.5 A / min. When the precursor reached 35 A and stabilized, the baffle was opened, and the evaporation time was controlled at 5 minutes. After evaporation, the sample was placed in a muffle furnace and annealed at 200°C for 1 hour.

[0092] Example 2

[0093] This embodiment provides a transparent optoelectronic thin film ZnO / Cs3Cu2I5:Eu heterojunction film, wherein the thickness of the ZnO film layer is 60 nm, the thickness of the Cs3Cu2I5:Eu film layer is 240 nm, and the doping amount of Eu in Cs3Cu2I5:Eu is 4.1 at.%. The preparation method is as follows:

[0094] (1) Substrate cleaning: The substrate with crystal orientation is <0001> The 10mm × 10mm Al2O3 substrate was sequentially ultrasonically cleaned with acetone, ethanol, and deionized water for 5 minutes each, then rinsed with flowing deionized water and dried with a nitrogen gun. Finally, it was placed on the sample stage of the magnetron sputtering vacuum chamber for deposition.

[0095] (2) Magnetron sputtering of ZnO thin film: ZnO is used as the target material, and radio frequency magnetron sputtering is used to deposit the thin film. Before the deposition begins, the pressure in the vacuum chamber is reduced to 10.-3 Pa, substrate stage temperature set to 80℃, substrate stage rotation speed 5rpm, substrate to target distance 12cm, deposition atmosphere argon, gas flow rate 40sccm, gas pressure 0.5Pa, RF power supply power 90W, pre-sputtering for 10min, then formal deposition for 0.5h.

[0096] (3) Pretreatment of copper-based halides: Weigh CsI, CuI and EuI2 in a glove box with a molar ratio of 3:1:0.5, where CsI is 1.559g, CuI is 0.381g and EuI2 is 0.406g. Place the weighed drugs in a mortar and grind for 10min to obtain precursor powder.

[0097] (4) Transfer substrate: The substrate that has completed magnetron deposition is inverted and installed on the substrate fixing stage of the thermal evaporation equipment to ensure that copper-based halide vapor can be evenly covered on the substrate surface during the evaporation process.

[0098] (5) Evaporation of Cs3Cu2I5:Eu thin film layer: Cs3Cu2I5 layer was deposited by single-source evaporation. 0.2g of uniformly mixed precursor powder was weighed and placed in a tungsten boat. Before starting the evaporation, the vacuum degree was first evaporated to 10. -4 Below Pa, the current was turned on and the temperature was increased at a rate of 4 A / min. When the precursor reached 32 A and stabilized, the baffle was opened, and the evaporation time was controlled at 10 minutes. After evaporation, the sample was placed in a muffle furnace and annealed at 170°C for 0.5 hours.

[0099] Example 3

[0100] This embodiment provides a transparent optoelectronic thin film ZnO / Cs3Cu2I5:Eu heterojunction film, wherein the thickness of the ZnO film layer is 600 nm, the thickness of the Cs3Cu2I5:Eu film layer is 30 nm, and the doping amount of Eu in Cs3Cu2I5:Eu is 0.6 at%. The preparation method is as follows:

[0101] (1) Substrate cleaning: The substrate with crystal orientation is <0001> The 10mm × 10mm Al2O3 substrate was sequentially ultrasonically cleaned with acetone, ethanol, and deionized water for 15 minutes each, then rinsed with flowing deionized water and dried with a nitrogen gun. Finally, it was placed on the sample stage of the magnetron sputtering vacuum chamber for deposition.

[0102] (2) Magnetron sputtering of ZnO thin film: ZnO is used as the target material, and radio frequency magnetron sputtering is used to deposit the thin film. Before the deposition begins, the pressure in the vacuum chamber is reduced to 10. -3Pa, substrate stage temperature set to 150℃, substrate stage rotation speed 20rpm, substrate to target distance 12cm, deposition atmosphere argon, gas flow rate 45sccm, gas pressure 2.5Pa, RF power supply power 200W, pre-sputtering for 20min, deposition time 4h.

[0103] (3) Pretreatment of copper-based halides: Weigh CsI, CuI and EuI2 in a glove box with a molar ratio of 3:1:0.1, where CsI is 1.559g, CuI is 0.381g and EuI2 is 0.082g. Place the weighed drugs in a mortar and grind for 20min to obtain precursor powder.

[0104] (4) Transfer substrate: The substrate that has completed magnetron deposition is inverted and installed on the substrate fixing stage of the thermal evaporation equipment to ensure that copper-based halide vapor can be evenly covered on the substrate surface during the evaporation process.

[0105] (5) Evaporation of Cs3Cu2I5:Eu thin film layer: Cs3Cu2I5 layer was deposited by single-source evaporation. 0.2g of uniformly mixed precursor powder was weighed and placed in a tungsten boat. Before starting the evaporation, the vacuum degree was first evaporated to 10. -4 Below Pa, the current was turned on and the temperature was increased at a rate of 3 A / min. When the precursor reached 38 A and stabilized, the baffle was opened, and the evaporation time was controlled at 1 minute. After evaporation, the sample was placed in a muffle furnace and annealed at 220°C for 2 hours.

[0106] Example 4

[0107] The difference between this embodiment and embodiment 1 is that, in this embodiment, the transparent photoelectric film is a ZnO / Cs3Cu2I5:Ce heterojunction film; in step (3), CsI, CuI and CeI3 reagents with a molar ratio of 3:1:0.25 are weighed.

[0108] The remaining preparation methods and parameters are consistent with those in Example 1.

[0109] Example 5

[0110] The difference between this embodiment and embodiment 1 is that, in this embodiment, the transparent photoelectric film is a ZnO / Cs3Cu2I5:Tb heterojunction film; in step (3), CsI, CuI and TbI3 reagents with a molar ratio of 3:1:0.25 are weighed.

[0111] The remaining preparation methods and parameters are consistent with those in Example 1.

[0112] Example 6

[0113] The difference between this embodiment and embodiment 1 is that in this embodiment, the transparent optoelectronic film is a Yb2O3 / Cs3Cu2I5:Eu heterojunction film; in step (2), Yb2O3 is used as the target material and the RF power supply power is 200W.

[0114] The remaining preparation methods and parameters are consistent with those in Example 1.

[0115] Example 7

[0116] The difference between this embodiment and embodiment 1 is that in this embodiment, the transparent optoelectronic film is a Ga2O3 / Cs3Cu2I5:Eu heterojunction film; in step (2), Ga2O3 is used as the target material and the RF power supply is 150W.

[0117] The remaining preparation methods and parameters are consistent with those in Example 1.

[0118] Example 8

[0119] The difference between this embodiment and embodiment 1 is that, in this embodiment, the transparent photoelectric film is a ZnO / CsCu2I3:Eu heterojunction film; in step (3), CsI, CuI and EuI2 reagents with a molar ratio of 0.75:1:0.25 are weighed; the rest of the preparation methods and parameters are consistent with those in embodiment 1.

[0120] Example 9

[0121] The difference between this embodiment and embodiment 1 is that, in this embodiment, the transparent photoelectric film is a ZnO / Cs3Cu2Cl5:Eu heterojunction film; in step (3), CsCl, CuCl and EuCl2 reagents with a molar ratio of 3:1:0.25 are weighed.

[0122] The remaining preparation methods and parameters are consistent with those in Example 1.

[0123] Example 10

[0124] The difference between this embodiment and embodiment 1 is that, in this embodiment, the transparent photoelectric film is a ZnO / Cs3Cu2Br5:Eu heterojunction film; in step (3), CsBr, CuBr and EuBr2 reagents with a molar ratio of 3:1:0.25 are weighed.

[0125] The remaining preparation methods and parameters are consistent with those in Example 1.

[0126] Example 11

[0127] The difference between this embodiment and embodiment 4 is that in this embodiment, the atomic percentage of Ce in Cs3Cu2I5:Ce is 7 at.%; in step (3), CsI, CuI and CeI3 reagents with a molar ratio of 3:1:1 are weighed.

[0128] The remaining preparation methods and parameters are consistent with those in Example 4.

[0129] Example 12

[0130] The difference between this embodiment and embodiment 1 is that, in this embodiment, the thickness of the Cs3Cu2I5 thin film layer is 550nm; and in step (5), the evaporation time is 25 minutes.

[0131] The remaining preparation methods and parameters are consistent with those in Example 1.

[0132] Comparative Example 1

[0133] The difference between this comparative example and Example 1 is that in this comparative example, the transparent photoelectric film is a ZnO / Cs3Cu2I5 heterojunction film, which is not doped with Eu, and EuI2 is not added in step (3);

[0134] The remaining preparation methods and parameters are consistent with those in Example 1.

[0135] Comparative Example 2

[0136] The difference between this comparative example and Example 1 is that in this comparative example, the transparent photoelectric film is a Si / Cs3Cu2I5:Eu heterojunction film, and high-purity silicon is used as the target material in step (2).

[0137] The remaining preparation methods and parameters are consistent with those in Example 1.

[0138] Comparative Example 3

[0139] The difference between this comparative example and Example 1 is that in this comparative example, the carrier transport layer is changed to PEDOT:PSS, and step (2) is changed to solution spin coating. 60 μL of PEDOT:PSS solution is dropped onto the substrate, first spin-coated at a low speed of 500 rpm for 10 s, and then spin-coated at a high speed of 4000 rpm for 60 s. After annealing at 120°C for 20 min in a vacuum drying oven, a PEDOT:PSS film is obtained.

[0140] The remaining preparation methods and parameters are consistent with those in Example 1.

[0141] Comparative Example 4

[0142] The difference between this comparative example and Example 1 is that in this comparative example, both the ZnO thin film layer and the Cs3Cu2I5:Eu thin film layer are prepared using a solution method, as detailed below:

[0143] (1) Substrate cleaning: The substrate with crystal orientation is <0001> The 10mm × 10mm Al2O3 substrate was sequentially ultrasonically cleaned with acetone, ethanol, and deionized water for 10 minutes each, then rinsed with flowing deionized water and dried with a nitrogen gun. Finally, it was placed on the sample stage of the magnetron sputtering vacuum chamber for deposition.

[0144] (2) Preparation of ZnO thin film: Potassium hydroxide (KOH, 1.48 g) was dissolved in 65 mL of methanol solution (room temperature). 2.95 g of zinc acetate dihydrate was added to 125 mL of methanol solution and heated in a water bath at 60 °C with constant stirring until completely dissolved. The methanol solution of potassium hydroxide was slowly added to the methanol solution of zinc acetate dihydrate using a syringe pump (time controlled within 20 minutes), and stirred at 60 °C for 2 hours. At this time, the solution was turbid and the nanoparticles began to precipitate. The suspension was centrifuged at 5000 rpm for 5 minutes, and the precipitate was washed repeatedly with methanol and centrifuged twice to finally obtain a white precipitate, which is ZnO nanocrystals. The ZnO nanocrystals were dispersed in 5 mL of ethanol for later use. 1 mL of ZnO nanocrystal solution was spin-coated onto the surface of the device at 1200 rpm using a spin coater. The device with the spin-coated ZnO nanocrystal solution was placed in a nitrogen environment and annealed at 80 °C for 20 minutes. The above operation was repeated once to obtain a white thin film uniformly distributed on the substrate.

[0145] (3) Preparation of Cs3Cu2I5:Eu thin film: Weigh 0.78g of CsI powder, 0.38g of CuI powder and 0.202g of EuI2 powder and dissolve them in 2mL of DMSO and DMF solvent in a 1:1 ratio; then, use a magnetic stirrer to stir the prepared solution rapidly at 60℃ for 12h; then filter it with a 0.22μm PTFE filter; then, place the substrate with ZnO nanocrystals spin-coated on a spin coater, and use a pipette to add 60μL of the prepared Cs3Cu2I5 precursor solution to the substrate surface. The spin-coating conditions are low speed 500r / min for 5s, high speed 4000r / min for 60s; add 10μl of antisolvent toluene in the last 15s of high speed rotation to accelerate the evaporation of the solution and speed up the crystallization process. Finally, the spin-coated sample was placed on a heating stage for high-temperature annealing at 100°C for 60 minutes. Both the spin-coating and annealing operations were performed in a glove box.

[0146] Performance Characterization

[0147] To verify the structural quality and photoelectric properties of the transparent optoelectronic thin film proposed in this invention, the heterojunction thin film material prepared in Example 1 was subjected to scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), photoluminescence (PL), and transmission spectroscopy tests. The test results are as follows: Figures 2-7 As shown.

[0148] In addition, the photoelectric thin films prepared in Examples 2-12 and Comparative Examples 1-4 were subjected to photoelectric tests at wavelengths of 200-800 nm, and the test results are shown in Table 1.

[0149] It should be noted that in the column containing the bandgap, the value to the left of the " / " represents the bandgap of the wide-bandgap semiconductor layer, and the value to the right of the " / " represents the bandgap of the copper-based halide layer. For example, in Example 1, 3.26 / 4.16 indicates that the bandgap of ZnO is 3.26 eV and the bandgap of Cs3Cu2I5:Eu is 4.16 eV. Additionally, the peak positions and quantum efficiencies in Table 1 are data at a wavelength of 290 nm.

[0150] Table 1

[0151]

[0152] like Figures 2-3 As shown, the heterojunction film prepared in Example 1 has uniform grain size, dense crystals, and a smooth morphology, indicating that the thermal evaporation process can effectively control the nucleation and growth of copper-based halide films. Figures 4-5 The EDS elemental distribution map and EDS energy spectrum were obtained. The results showed that Cs, Cu, I, Eu and other elements were uniformly distributed in the film and no obvious aggregation was observed, indicating that the film formation process was stable and the composition was well controlled. Figures 6-7 The photoluminescence and transmission spectra of the heterojunction are presented. The photoluminescence (PL) emission peak is located at 440 nm, exhibiting a broad blue emission characteristic, mainly attributed to the self-trapped exciton emission mechanism of Cs3Cu2I5. The transmission spectrum shows that the ultraviolet absorption edge of the heterojunction film is located in the UV-B region, demonstrating the potential application value of this structure in multi-band ultraviolet-responsive devices.

[0153] In contrast, the heterostructure film prepared by solution spin coating in Comparative Example 4 suffers from surface roughness and uneven crystallization, and its transmittance and luminescence intensity are both lower than those of the all-vapor phase preparation method proposed in this invention. Therefore, this invention successfully prepares a dense, uniformly composed, and optically superior fully transparent heterostructure film using a combined magnetron sputtering and thermal evaporation process, exhibiting good controllability and device compatibility. As shown in Table 1, the data from Example 1 and Comparative Examples 1-3 indicate that in this invention, the copper-based halide doped with metal elements and the wide-bandgap semiconductor material work synergistically. Only when both conditions are met simultaneously can the film achieve high transmittance. In Comparative Example 2, because the Si transport layer is opaque, visible light transmission is significantly reduced.

[0154] As can be seen from the data comparison of Examples 4-5 in Table 1, in this invention, when the doping metal element is Eu and / or Ce, better results can be achieved compared to other doping elements; as can be seen from the data comparison of Examples 1 and Examples 6-12, changing the type of wide bandgap semiconductor and changing CsX a and CuX b The proportion of X, the type of X, the amount of metal doping, or the thickness of the copper-based halide layer can all affect the performance of the thin film. In practical applications, the appropriate type of material or parameters can be selected as needed.

[0155] In summary, this type of heterostructure thin film can not only achieve the control of emission wavelength and ultraviolet response range by adjusting the copper-based halide composition or replacing the wide bandgap semiconductor material, but also has high transparency and good structural quality, laying a technical foundation for its application in transparent optoelectronic devices such as ultraviolet detectors and light-emitting diodes.

[0156] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A transparent optoelectronic thin film, characterized in that, The transparent optoelectronic thin film is a composite layer with a heterostructure formed by stacked wide bandgap semiconductor layers and copper-based halide layers, wherein the bandgap E of the wide bandgap semiconductor layer is... g ≥3eV, the copper-based halide layer includes Cs m Cu n X m+n RE, where X includes any one or at least two of Cl, Br or I, RE includes any one or at least two of rare earth metals, 1≤m≤3, 1≤n≤2.

2. The transparent photoelectric thin film according to claim 1, characterized in that, The band gap of the wide bandgap semiconductor layer is 3eV~5eV; Preferably, the wide bandgap semiconductor layer comprises any one or a combination of at least two of ZnO, MgZnO, Ga2O3, GaN, or Yb2O3.

3. The transparent photoelectric thin film according to claim 1 or 2, characterized in that, The atomic percentage of the RE in the copper-based halide layer is 0.5 at.% to 4 at.%; Preferably, the RE includes any one or a combination of at least two of Eu, Ce, Tb, Sm or Dy, and more preferably Eu and / or Ce.

4. The transparent photoelectric thin film according to any one of claims 1-3, characterized in that, The thickness of the wide bandgap semiconductor layer is 60nm~600nm; Preferably, the thickness of the copper-based halide layer is 30 nm to 240 nm; Preferably, the transmittance of the transparent optoelectronic film is ≥80%.

5. A method for preparing a transparent optoelectronic thin film as described in any one of claims 1-4, characterized in that, The preparation method includes: depositing a wide bandgap semiconductor layer on a substrate by radio frequency magnetron sputtering, then depositing a copper-based halide layer on the wide bandgap semiconductor layer by single-source thermal evaporation, and finally annealing.

6. The preparation method according to claim 5, characterized in that, The radio frequency magnetron sputtering includes: placing the substrate in the vacuum chamber of the radio frequency magnetron sputtering equipment and fixing it on the heating stage; then installing a wide bandgap semiconductor target on the target gun of the radio frequency magnetron sputtering; adjusting the system parameters and starting the sputtering program. Preferably, the substrate is cleaned before use; Preferably, the substrate includes a transparent conductive substrate, an ITO glass substrate, an FTO glass substrate, or a C-plane Al2O3 substrate.

7. The preparation method according to claim 6, characterized in that, The radio frequency magnetron sputtering is a single-target sputtering; Preferably, before the sputtering process begins, the air pressure in the vacuum chamber is adjusted to 10. -3 Below Pa; Preferably, the temperature of the heating table is 25℃~600℃, more preferably 80℃~150℃; Preferably, the rotation speed of the heating table is 5 rpm to 20 rpm; Preferably, the distance between the substrate and the wide bandgap semiconductor target is 5cm to 12cm; Preferably, the atmosphere of the sputtering process includes argon; Preferably, the purity of the argon gas is ≥99.99%; Preferably, the gas flow rate of the sputtering process is 40 sccm to 50 sccm; Preferably, the gas pressure of the sputtering process is 0.5 Pa to 2.5 Pa; Preferably, the power of the sputtering process is 70W~200W; Preferably, the sputtering process includes pre-sputtering and formal sputtering; Preferably, the pre-sputtering time is 10 min to 20 min; Preferably, the formal sputtering time is 0.5h to 4h.

8. The preparation method according to any one of claims 5-7, characterized in that, The single-source thermal evaporation method includes: applying (CsX) a ) m (CuX) b ) n (REX) c ) t The mixture yields a copper-based halide precursor, which is then loaded into a tungsten boat within the thermal evaporation equipment chamber. The substrate with the deposited wide-bandgap semiconductor layer is inverted and mounted on the substrate stage of the thermal evaporation equipment. System parameters are adjusted, and the thermal evaporation process is started. a X b and X c Each can independently include any one of Cl, Br or I, 1≤m≤3, 1≤n≤2, 0<t≤0.

5.

9. The preparation method according to claim 8, characterized in that, The mixing method includes grinding; Preferably, the grinding process is carried out in the dark; Preferably, the grinding time is 10 min to 20 min; Preferably, before the single-source thermal evaporation begins, the vacuum level inside the thermal evaporation equipment cavity is adjusted to 1×10⁻⁶. -5 Pa ~ 1×10 - 4 Pa; Preferably, the rotation speed of the substrate stage is 5 rpm to 20 rpm; Preferably, the distance between the tungsten boat and the substrate is 5cm to 12cm; Preferably, the tungsten boat is heated by current gradient control; Preferably, in the current gradient control, the current rise rate is 3A / min to 4A / min; Preferably, the cutoff current of the current gradient control is 32A~38A; Preferably, the baffle is opened to start hot vapor deposition after the saturated vapor pressure of the copper-based halide precursor has stabilized. Preferably, the rate of the single-source thermal evaporation is 0.1 Å / s to 1 Å / s; Preferably, the single-source thermal evaporation time is 1 min to 30 min, and more preferably 1 min to 5 min.

10. An application of the transparent photoelectric thin film as described in any one of claims 1-4, characterized in that, The applications include those in transparent optoelectronic devices.

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