A high-bandwidth light-emitting diode, its fabrication method, and an illumination system

Abstract

This invention discloses a high-bandwidth light-emitting diode (LED), its fabrication method, and an illumination system, relating to the field of semiconductor optoelectronics technology. The LED includes a driving backplane and multiple light-emitting pixels disposed thereon. Each light-emitting pixel is a vertically stacked hybrid light-emitting unit, comprising: a first electrode, a gallium nitride-based micron-sized LED subunit, an interface charge generation layer, an organic light-emitting diode subunit, and a second electrode. This invention maintains high-quality white light illumination while increasing the modulation bandwidth to the megahertz level, breaking through the bandwidth bottleneck of organic light-emitting diodes, and can be widely applied in visible light communication, smart lighting, and automotive optical interconnection, among other fields.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronics technology, and more specifically, to a high-bandwidth light-emitting diode, its fabrication method, and an illumination system. Background Technology

[0002] With the rapid development of mobile internet, the Internet of Things, and 6G mobile communication technology, visible light communication, as a new type of wireless communication technology, has become one of the key candidate technologies for 6G mobile communication due to its advantages such as combining lighting and communication, requiring no spectrum licensing, having no electromagnetic interference, and high security. Visible light communication systems require the light source to have both excellent lighting performance and high-speed modulation response capability.

[0003] Currently, the core light-emitting element of visible light communication systems mainly uses inorganic light-emitting diodes (LEDs). Inorganic LEDs, especially gallium nitride-based blue LEDs, have advantages such as high modulation bandwidth, fast response speed, and good stability, enabling them to support data transmission at the gigabits per second level. However, traditional inorganic LEDs are rigid point light sources, which suffer from problems such as poor light uniformity, significant glare effect, and limited spectral tunability. Furthermore, they are difficult to make flexible and large-area surface light sources, limiting their in-depth application in high-end lighting and intelligent human-computer interaction scenarios.

[0004] Organic light-emitting diodes (OLEDs) possess unique advantages such as surface light source, flexibility, customizable spectrum, and low blue light hazard, making them ideal light sources for achieving high-quality illumination. However, OLEDs are limited by the low carrier mobility and microsecond-level long exciton lifetime of organic semiconductor materials, resulting in a -3dB modulation bandwidth that is typically only a few hundred kilohertz, far lower than that of inorganic light-emitting diodes. This inherent bottleneck severely restricts their application in high-speed visible light communication.

[0005] In existing technologies, some schemes attempt to vertically stack gallium nitride-based light-emitting diodes (LEDs) and organic light-emitting diodes (OLEDs) in series to combine their spectral advantages and achieve efficient white light emission. However, this macroscopic unit-series structure does not solve the bandwidth limitation problem inherent in OLEDs; the overall device response speed is still limited by the relatively slow-responding OLED units, hindering high-speed communication. Furthermore, traditional large-area LED structures suffer from current congestion, limiting their modulation performance at high current densities. Therefore, this application proposes a high-bandwidth LED, its fabrication method, and an illumination system to at least partially address the problems inherent in existing technologies. Summary of the Invention

[0006] In view of the aforementioned problems, this application is made to provide a high-bandwidth light-emitting diode, a method for fabricating it, and a lighting system that overcomes or at least partially solves the aforementioned problems.

[0007] To achieve the above objectives, the present invention provides a high-bandwidth light-emitting diode, comprising:

[0008] Drive backplane; and

[0009] Multiple light-emitting pixels are disposed on the driving backplate, each of the light-emitting pixels being a vertically stacked hybrid light-emitting unit, the hybrid light-emitting unit comprising:

[0010] A first electrode is formed on the drive backplate;

[0011] A gallium nitride-based micron-sized light-emitting diode subunit is formed on the first electrode and is used to emit light of a first wavelength. The lateral dimension of the gallium nitride-based micron-sized light-emitting diode subunit is 5-50 μm.

[0012] An interface charge generation layer is formed on the light-emitting side of the gallium nitride-based micron light-emitting diode subunit, comprising a transparent conductive oxide layer, a first charge generation sublayer, and a second charge generation sublayer stacked sequentially.

[0013] An organic light-emitting diode subunit is formed on the interface charge generation layer and is used to emit light of a second wavelength, which is different from the first wavelength.

[0014] The second electrode is formed on the organic light-emitting diode subunit;

[0015] The driving backplate is connected to the first electrode and the second electrode via wires, and is used to independently control the luminous intensity of the gallium nitride-based micron-sized light-emitting diode subunit and the organic light-emitting diode subunit in each of the light-emitting pixels.

[0016] Optionally, the peak emission wavelength of the gallium nitride-based micron-sized light-emitting diode subunit is 450-480 nm;

[0017] The organic light-emitting diode subunit is a phosphorescent organic light-emitting diode or a thermally activated delayed fluorescence organic light-emitting diode, and its emission spectrum includes at least one wavelength component longer than 500 nm to achieve spectral complementarity with the gallium nitride-based micron light-emitting diode subunit to form white light.

[0018] Optionally, in the interface charge generation layer:

[0019] The transparent conductive oxide is indium tin oxide or indium zinc oxide, with a thickness of 50-200 nm.

[0020] The first charge-generating sublayer is a HAT-CN thin film with a thickness of 5-20 nm;

[0021] The second charge-generating sublayer is an n-type doped organic electron transport material, wherein the n-type dopant is LiNH2, Cs2CO3 or Rb2CO3, and the organic electron transport material is Bphen, TPBi or TmPyPB.

[0022] Optionally, the driving backplane is a silicon-based backplane containing complementary metal-oxide-semiconductor driving circuitry or a glass-based backplane containing thin-film transistor driving circuitry.

[0023] Optionally, it may also include a scattering layer and / or a wavelength conversion layer covering the plurality of light-emitting pixels for homogenizing and color correcting the emitted light from the plurality of light-emitting pixels.

[0024] Optionally, the plurality of light-emitting pixels are arranged in an array on the driving backplane, and two light-emitting pixels in adjacent rows are staggered by one pixel position in the column direction.

[0025] Optionally, the gallium nitride-based micron-sized light-emitting diode subunit is a blue light emitting unit, and the organic light-emitting diode subunit is a white light compensation unit co-doped with red and green light. Under the independent control of the driving backplane, the gallium nitride-based micron-sized light-emitting diode subunit is loaded with a high-frequency communication modulation signal, and the organic light-emitting diode subunit is loaded with a DC or low-frequency illumination bias signal.

[0026] Optionally, the HAT-CN film in the interface charge generation layer reduces the root mean square roughness of the transparent conductive oxide surface to below 1 nm and increases the effective work function of the transparent conductive oxide by at least 0.3 eV.

[0027] This application discloses a method for fabricating a light-emitting diode (LED), comprising the following steps:

[0028] Step 1: Fabricate a patterned first electrode on the driving backplane;

[0029] Step 2: An array of gallium nitride-based micron-sized light-emitting diode subunits is fabricated on the first electrode through epitaxial growth, photolithography, and etching processes. The mesa of each gallium nitride-based micron-sized light-emitting diode subunit is isolated by a silicon dioxide layer.

[0030] Step 3: Deposit and pattern the interface charge generation layer across the entire device surface so that it only covers the light-emitting region of the gallium nitride-based micron-sized light-emitting diode subunit;

[0031] Step 4: Sequentially deposit each organic functional layer of the organic light-emitting diode subunit and the second electrode on the interface charge generation layer using a vacuum thermal evaporation process.

[0032] Step 5: Lead the first and second electrodes of all light-emitting pixels to the driving circuit through the wires on the driving backplate.

[0033] Optionally, the patterning of the interface charge generation layer is performed using a high-precision mask or laser direct writing process, with a patterning accuracy of ±1μm.

[0034] Optionally, the organic functional layer of the organic light-emitting diode subunit includes a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, and an electron injection layer.

[0035] Some embodiments of this application disclose a lighting system including the aforementioned high-bandwidth light-emitting diode, and connected thereto:

[0036] Power supply and control module for providing lighting drive and communication modulation signals;

[0037] A photoelectric detection and demodulation module for receiving visible light signals emitted by the light-emitting diode and converting them into electrical signals.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] By applying high-frequency communication modulation signals only to the fast-response gallium nitride-based micron-sized light-emitting diode (LED) subunits, while the organic light-emitting diode (OLED) subunits only provide DC or low-frequency illumination bias, the device's -3dB modulation bandwidth is increased from the hundreds of kilohertz to the megahertz range—an improvement of two orders of magnitude—while maintaining high-quality white light illumination, thus meeting the requirements for megabit-per-second visible light communication. Using independent driving backplanes to control the luminous intensity of the two light-emitting subunits within the same pixel, a collaborative working mechanism is achieved for the first time: "illumination color is dominated by the OLED, and communication rate is dominated by the micron-sized LED," with neither interfering with the other. The three-layer structure of transparent conductive oxide / HAT-CN / n-type doped electron transport layer not only reduces the surface roughness of the transparent conductive oxide to below 1 nm and increases the work function by at least 0.3 eV, but also improves the current efficiency of the series device by over 100% and the external quantum efficiency to 21.5%, while precisely controlling the turn-on voltage to the sum of the turn-on voltages of the two subunits. By limiting the lateral dimensions of gallium nitride-based light-emitting diodes (LEDs) to 5-50 μm, the current crowding effect of traditional large-size LEDs is effectively avoided, ensuring uniform carrier injection and rapid modulation response under high current density. Through spectral complementarity between blue micron-sized LEDs and red / green / yellow organic light-emitting diodes (OLEDs), uniform white light emission with a color rendering index as high as 85 and an adjustable correlated color temperature (4500K-5500K) is achieved. Simultaneously, a scattering layer can be applied to achieve surface emission. Multiple emitting pixels can form a high-density array, and each micron-sized LED subunit can be independently loaded with a communication modulation signal, constructing a multi-input multi-output visible light communication transmission array, greatly increasing the total communication capacity of the system. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a schematic cross-sectional view of a high-bandwidth light-emitting diode based on a hybrid integrated pixel array, provided as an embodiment of the present invention.

[0042] Figure 2 This is a simulation diagram of the current density distribution of a gallium nitride-based micron-sized light-emitting diode subunit provided in an embodiment of the present invention.

[0043] Figure 3 A comparison diagram of the frequency response curves of a hybrid light-emitting pixel provided in an embodiment of the present invention.

[0044] Figure 4 This is a schematic diagram of the electrode connection of multiple light-emitting pixels according to an embodiment of the present invention.

[0045] Figure 5 The electroluminescence spectrum of a light-emitting diode is provided in an embodiment of the present invention.

[0046] Figure 6 An eye diagram of a light-emitting diode in visible light communication testing is provided as an embodiment of the present invention.

[0047] In the diagram: 100, silicon-based driving backplane; 200, pixel; 210, first electrode; 220, Micro-LED subunit; 221, silicon dioxide layer; 230, deposited composite layer structure; 231, ITO layer; 232, HAT-CN layer; 233, Bphen layer; 240, OLED subunit; 250, second electrode. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] Example 1

[0050] This embodiment provides a high-bandwidth, high color rendering index white light-emitting diode panel for smart lighting and high-speed indoor visible light communication.

[0051] like Figure 1 As shown, multiple light-emitting pixels 200 are fabricated on a silicon-based driving backplane 100 containing CMOS driving circuitry. Each pixel 200 is a vertically connected series structure, and each pixel 200 serves as a basic RGB light-emitting unit, comprising: a sandwich structure as the main hierarchical structure, a bottom GaN (gallium nitride) Micro-LED, a middle charge pump layer (i.e., an interface charge generation layer), and a bottom OLED; specifically including:

[0052] The bottom portion is the first electrode 210, i.e., the anode, which can preferably be as follows: Figure 1 The Au (copper) shown is used as the main material, specifically a Ti (titanium) / Pt (platinum) / Au (copper) multilayer metal with a thickness of 200nm, connected to the pixel driving output terminal of the driving backplane 100. The middle layer is a GaN blue micro-LED subunit 220. Its epitaxial structure from bottom to top includes n-GaN (2μm thick), InGaN / GaN multiple quantum wells (3 periods, emission wavelength ~456nm), and p-GaN (200nm thick). It is processed into a cylindrical mesa with a diameter of 15μm through photolithography and inductively coupled plasma etching processes. The mesa sidewalls are treated with potassium hydroxide solution wet etching to remove etching damage, and the sidewalls are passivated and the inter-units are isolated by a silicon dioxide layer 221 grown by plasma-enhanced chemical vapor deposition. This micron-scale design ensures uniform current injection and efficient light extraction. Figure 2 As shown, the Micro-LED subunit 220 of this embodiment still exhibits a highly uniform current density distribution under a driving current of 100mA, effectively avoiding the current crowding effect commonly found in traditional large-size LEDs, and providing a physical basis for stable operation under high-frequency modulation.

[0053] The interface charge generation layer, also known as the charge pump, is a composite layer structure 230 that is sequentially deposited on the p-GaN light-emitting surface of the GaN Micro-LED subunit 220.

[0054] The aforementioned composite layer structure 230 includes an ITO layer 231, a HAT-CN layer 232, and a Bphen layer 233.

[0055] The aforementioned ITO layer 231, preferably 80 nm thick, is deposited using magnetron sputtering and serves as a transparent electrode and optical coupling layer. Its high transmittance (>85% @456 nm) ensures efficient blue light emission.

[0056] The HAT-CN layer 232 is preferably 10 nm thick and is deposited using a vacuum thermal evaporation method. The introduction of the HAT-CN layer 232 improves the work function of the ITO layer 231 and enhances the built-in electric field at the interface through its strong electron accepting ability. On the other hand, atomic force microscopy tests show that the HAT-CN layer 232 can reduce the root mean square roughness of the ITO layer 231 surface from 2.69 nm to 0.73 nm, significantly smoothing the interface morphology and reducing interface trap states.

[0057] The aforementioned LiNH2-doped Bphen layer 233, serving as the host electron transport material, has a LiNH2 doping concentration of 10 vol% and a thickness of 40 nm, and was also prepared using a vacuum thermal co-evaporation method. This n-type doped layer exhibits excellent electron injection and transport capabilities, providing an efficient channel for injecting electrons from GaN Micro-LED subunit 220 to OLED subunit 240.

[0058] The top OLED subunit 240 has the following structure: a hole injection / transport layer (TCTA), preferably 20 nm thick, with a HOMO level of -5.6 eV, forming a stepped energy level match with the underlying HAT-CN layer 232, which is beneficial for hole injection and transport; a light-emitting layer, preferably CBP host material, co-doped with 7 vol% Ir(ppy)2(acac) (green phosphorescent material) and 1 vol% Ir(MDQ)2(acac) (red phosphorescent material), with a thickness of 30 nm. This light-emitting layer produces a yellow-green-red composite spectrum with peaks at 532 nm and 618 nm under electrical excitation; and an electron transport layer (TmPyPB), preferably 40 nm thick, with a LUMO level of -2.7 eV, which matches well with the cathode work function.

[0059] The aforementioned second electrode 250, i.e., the cathode, is preferably a LiF (lithium fluoride) and Al (aluminum) composite layer (1nm / 100nm), with the LiF layer used to lower the electron injection barrier. This cathode is connected to the common cathode line of the drive backplane 100 via a via.

[0060] A scattering film (not shown in the figure) is applied to the light-emitting side of the entire panel to mix the light emitted by each pixel, eliminate pixel boundaries, and obtain a uniform surface light emission effect.

[0061] In this embodiment, the driving backplane 100 can independently control the luminous intensity of the GaN Micro-LED subunit 220 and OLED subunit 240 within each luminous pixel 200. This structure achieves physical decoupling of communication and illumination functions at the pixel level.

[0062] The high-frequency communication modulation signal is applied only to the fast-response GaN Micro-LED subunit 220, while the OLED subunit 240 only provides stable DC or low-frequency component background light. Since the human eye is not sensitive to high-frequency flicker, and the photodetector can efficiently respond to the high-frequency modulation of the GaN Micro-LED subunit 220, this device overcomes the bandwidth bottleneck of OLED without sacrificing illumination quality.

[0063] Compared with the existing technology that treats the entire series device as a whole for driving, the present invention achieves a collaborative working mechanism in the same light-emitting device by independently addressing and controlling the two light-emitting sub-units inside the hybrid pixel. This mechanism, in which "the illumination color is dominated by OLED and the communication rate is dominated by Micro-LED", fundamentally solves the technical problem of insufficient OLED bandwidth.

[0064] Furthermore, the three interfacial charge generation layers of ITO layer 231 / HAT-CN layer 232 / Bphen layer 233:LiNH2 used in this embodiment are not simply superimposed, but rather produce a synergistic effect.

[0065] First, the ITO layer 231 ensures good light transmittance and conductivity. Second, the HAT-CN layer 232 increases the effective work function of the ITO layer 231 from 4.7 eV to approximately 5.1 eV through the interfacial dipole effect, enhancing the ability to inject holes into the underlying p-GaN. Simultaneously, the planarization effect of the HAT-CN layer 232 on the surface of the ITO layer 231 reduces the interface defect state density and decreases nonradiative recombination. Finally, the Bphen:LiNH2 layer provides an efficient channel for electron generation and injection. Capacitance-voltage characteristic tests show that the built-in electric field strength of this charge generation layer can reach 1.6–3.5 MV / cm, sufficient for efficiently disassembling excitons or directly tunneling to generate free carriers.

[0066] The optimized interface charge generation layer ensures that the turn-on voltage of the series device is precisely equal to the sum of the turn-on voltages of the two sub-units (ideal series connection), and the current efficiency is improved from 28.1 cd / A in the control group without the HAT-CN layer to 58.6 cd / A, an improvement of over 100%. More importantly, this interface layer provides an efficient and stable electrical bridge between GaN (inorganic semiconductor) and OLED (organic semiconductor), two material systems with vastly different properties, solving the core interface problem in heterogeneous integration.

[0067] In terms of optoelectronic performance, driving a single GaN Micro-LED subunit 220 yields pure blue light emission with a peak wavelength of 456 nm and a full width at half maximum (FWHM) of 35 nm. Driving both subunits simultaneously produces white light composed of a mixture of 456 nm blue light and 532 nm / 618 nm red and green light. At 10 mA / cm²...2 At a given current density, the device has color coordinates of (0.36, 0.33), a correlated color temperature of 4500K, and a color rendering index of 85. Its current efficiency is 58.6 cd / A, and its external quantum efficiency is 21.5%, comparable to the highest efficiency of macroscopic hybrid series devices in the prior art, proving that miniaturization did not lead to efficiency loss.

[0068] Regarding modulation bandwidth (a core breakthrough), the electroluminescence frequency response of individually driven OLED sub-units 240 and hybrid driven (GaN units loaded with modulation signals, OLED units loaded with constant bias voltage) within the same pixel 200 were tested respectively. Figure 3 As shown, the -3dB bandwidth of a single OLED subunit 240 is only 308kHz (dominated by green light), consistent with existing technologies. However, with hybrid driving, since the high-frequency modulation signal is only applied to the GaN Micro-LED subunit 220, the overall device's -3dB bandwidth increases to 22.6MHz (measured value), which is two orders of magnitude (73 times) higher than that of a pure OLED. This bandwidth fully meets the requirements for megabit-per-second visible light communication.

[0069] In terms of communication performance, non-return-to-zero on / off keying modulation was used, and the LED panel successfully transmitted 2... 7 -1 pseudo-random sequence. At a free space distance of 2 meters, the orthogonal amplitude modulation constellation diagram at the receiver is clear, and the eye diagram is measured, as shown below. Figure 6 The visible light communication test eye diagram shown indicates good eye opening and steep rising and falling edges. At a data transmission rate of 50 Mbps, the system bit error rate is as low as 1.2 × 10¹⁴. -6 This is well below the forward error correction threshold (3.8e-3), while the panel still provides over 1500 cd / m². 2 Uniform white light illumination.

[0070] It's important to note that an eye diagram is a highly intuitive graphical tool for testing high-speed digital signals. Simply put, it's a pattern resembling an "eye" formed on an oscilloscope by aligning and overlapping countless waveform segments of "0" and "1" in a high-speed digital signal according to clock cycles. It's a core method for quickly evaluating signal quality and system performance.

[0071] There is a core principle in interpreting eye diagrams: the wider and clearer the "eyes" (Q factor) are, the better the signal quality; the smaller and blurrier the "eyes" are, the worse the signal quality.

[0072] To complete the eye diagram test of LED light signals, it is usually necessary to set up an optical communication test platform, which mainly includes the following equipment:

[0073] Sampling Oscilloscope / Digital Communication Analyzer (DCA): This is the core host of the test. Its function is to capture high-speed signals and plot eye diagrams. Ordinary oscilloscopes often have insufficient bandwidth, while sampling oscilloscopes (such as the Keysight N1000A / DCA-X series, Lianxun Instruments DCA6201, etc.) are designed specifically for optical communication and can accurately reconstruct high-speed waveforms.

[0074] Optical sampling head / O / E converter: This is the key front end connecting the LED and the oscilloscope. Because the oscilloscope can only measure electrical signals, the optical sampling head must linearly convert the light signal (changes in optical power) emitted by the LED into a voltage signal before sending it to the oscilloscope.

[0075] Bit Error Rate Tester (BERT): Its role is to act as a "starter". BERT generates standard, known pseudo-random binary sequence (PRBS) electrical signals to drive your LEDs. This allows the receiver (oscilloscope) to know what "0"s and "1"s it should receive, enabling precise alignment and superposition.

[0076] Clock Recovery Unit (CRU / CDR): If the light signal emitted by the LED does not have a separate clock line, this device is needed to "extract" the clock signal from the data stream and tell the oscilloscope when to capture the waveform.

[0077] The entire testing process can be divided into the following steps:

[0078] (1) Driving LED light: Use a BERT (Bit Error Rate Tester) or a high-quality pattern generator to output a high-speed pseudo-random electrical signal (such as PRBS2). 7 -1 or 2 31 The -1 sequence is directly loaded onto the LED communication driver circuit, causing the LED to blink at high speed according to this sequence (lighting up represents "1", and not emitting light or having a faint light represents "0").

[0079] (2) Photoelectric conversion: The light emitted by the LED is transmitted to the optical sampling head through an optical fiber (or through lens coupling if it is free space communication). The photodetector inside the optical sampling head converts the changes in optical power into corresponding analog voltage waveforms in real time.

[0080] (3) Capture and overlay (eye diagram generation): The electrical signal output from the optical sampling head is connected to the sampling oscilloscope. The oscilloscope uses the recovered clock signal as a reference to capture the voltage waveform of thousands of bit cycles and continuously overlay and accumulate it on the screen.

[0081] Example 2

[0082] Referring to the structure and fabrication method of Example 1, only the emitting layer of the OLED subunit was replaced with a yellow phosphorescent material PO-01 (doping concentration 5 vol%), forming a single-emitting-layer yellow OLED. The peak emission wavelength of this yellow OLED is 560 nm. Combined with a GaN blue micro-LED, it forms a blue-yellow complementary white light emitting device, the spectrum of which is shown below. Figure 5 The image shows the EL spectrum of the blue-yellow hybrid tandem device (blue light 456nm + yellow light 560nm).

[0083] Test results show that this hybrid pixel operates at 10mA / cm 2 The color coordinates are (0.33, 0.34), and the correlated color temperature is 5500K. Its -3dB modulation bandwidth also reaches 20.1MHz, confirming the universality of the technical solution of this invention for different OLED luminescent material systems. This embodiment demonstrates that regardless of whether the OLED luminescent layer is a single color or a mixture of multiple colors, as long as it forms spectral complementarity with the underlying GaN Micro-LED subunit 220, high bandwidth performance can be obtained through the hybrid integrated pixel structure of this invention.

[0084] Comparative Example 1

[0085] To demonstrate the necessity of the HAT-CN layer 232 in the interface charge generation layer, a control device was fabricated. This control device differs from Example 1 only in that it does not contain the HAT-CN layer 232 in the interface charge generation layer; that is, its structure is ITO / Bphen:LiNH2.

[0086] Performance test results show that the series resistance of the control device is significantly increased, and the turn-on voltage is 1.8V higher than that of Example 1. Under the same drive current, its current efficiency is only 28.1 cd / A, half that of Example 1. More importantly, its -3dB modulation bandwidth is only 2.3MHz, far lower than that of Example 1. The frequency response curve shows obvious distortion, indicating the space charge accumulation effect caused by carrier injection imbalance. This comparative example strongly demonstrates the key role of the HAT-CN layer 232 in optimizing interface energy level matching, reducing contact resistance, and balancing carrier injection, which is an indispensable technical feature for achieving high efficiency and high bandwidth in this invention.

[0087] Comparative Example 2

[0088] To demonstrate the bandwidth advantage brought about by the size effect of Micro-LEDs, a control device was fabricated. The only difference between this control device and Example 1 is that the size of the GaN-based LED subunit was replaced from 15 μm with a large-area LED of 300 μm × 300 μm.

[0089] Performance test results show that, under the same current density, the -3dB bandwidth of the large-area LED device is only 4.5MHz due to severe current crowding, far lower than the 22.6MHz of Example 1. The electroluminescence near-field distribution map shows that the light emission of the large-area LED is mainly concentrated in the electrode edge region, with weaker light emission in the central region. This non-uniform carrier distribution leads to a significant decrease in its modulation response speed. This comparative example demonstrates that miniaturizing the LED size to the micrometer level (5-50μm) is one of the necessary conditions for achieving the high bandwidth performance of this invention. The micrometer-scale mesa structure ensures uniform current injection and shorter carrier transport time.

[0090] Example 3

[0091] This embodiment provides a large-area lighting communication panel, which can be arrayed and driven. For example... Figure 4 As shown, multiple light-emitting pixels 200 are arranged in an array on the driving backplane 100, forming a pixel matrix of m×n pixels 200. For example, if m=320 and n=240, a pixel matrix of 320×240 is formed. The second electrode 250 of organic light-emitting diode subunits (i.e., OLED subunits 240) located in the same column and emitting the same color is connected to the same driving port through the same trace, while the first electrode 210 of each gallium nitride-based micro-LED subunit (i.e., GaN Micro-LED subunit 220) is connected to an independent driving port through an independent trace.

[0092] The driving architecture is conceived as follows: the OLED sub-unit 240 provides a large area of ​​uniform background illumination color. Its response speed is relatively slow, requiring no independent high-frequency control. Therefore, it can be controlled using a passive matrix row and column scanning method, or even by connecting the second electrodes 250 of all OLED sub-units 240 together for unified brightness control. Each GaN Micro-LED sub-unit 220 serves as an independent communication channel, where communication modulation signals can be independently and parallelly loaded by high-speed transistors in the driving backplane 100, forming a multiple-input multiple-output visible light communication emission array, greatly improving the system's total communication capacity. This embodiment further demonstrates the enormous application potential of this invention in the fields of intelligent lighting and spatial optical communication.

[0093] In summary, this invention, through the innovative design of a micrometer-scale GaN-OLED hybrid pixel array, combined with an optimized interface charge generation layer and a 200-level independent driving architecture for each pixel, successfully fabricates a novel LED light source that combines high luminous efficiency, high color rendering index, high modulation bandwidth, and intelligent controllability. This light source can be widely applied in next-generation visible light communication, virtual reality / augmented reality, automotive optical interconnection, and smart lighting.

[0094] Example 4

[0095] This embodiment provides another way to implement a high-bandwidth light-emitting diode, specifically illustrating different material combinations in the interface charge generation layer, staggered arrangement of the pixel array, and high-precision patterning process.

[0096] This embodiment has a structure that is basically the same as that of Embodiment 1, the difference being the choice of material for the interface charge generation layer as follows: Transparent conductive oxide layer: Indium zinc oxide (IZO) is used instead of ITO, with a thickness of 120nm (still in the range of 50-200nm). IZO has a smoother surface morphology and higher infrared transmittance, making it suitable for scenarios requiring broad-spectrum transmission.

[0097] The first charge-generating sublayer still uses a HAT-CN thin film with a thickness of 15 nm (in the range of 5-20 nm).

[0098] The second charge-generating sublayer employs an n-type doped organic electron transport material, wherein: the electron transport host material is selected from TPBi (1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene) or TmPyPB (1,3,5-tris[(3-pyridyl)-3-phenyl]benzene), and TPBi is used as an example in this embodiment; the n-type dopant is selected from Cs2CO3 (cesium carbonate) or Rb2CO3 (rubidium carbonate), and Cs2CO3 is used as an example in this embodiment, with a doping concentration of 8 vol% and a thickness of 50 nm.

[0099] The second charge-generating sublayer was prepared by vacuum thermal co-evaporation, and its electron injection capability is comparable to or better than that of Bphen:LiNH2 in Example 1.

[0100] Performance tests show that the device using the IZO / HAT-CN / TPBi:Cs2CO3 structure has a turn-on voltage that is basically the same as that of Example 1 (approximately 5.2V), and at 10 mA / cm 2 The current efficiency at the current density is 56.9 cd / A, and the -3dB modulation bandwidth is 21.8MHz, which is comparable to the results of Example 1.

[0101] Various transparent conductive oxides, n-type dopants, and electron transport host materials can all achieve the technical effects of this invention, and these are equivalent substitutions that can be reasonably expected by those skilled in the art.

[0102] In this embodiment, multiple light-emitting pixels are arranged in an array on the driving backplane, and two light-emitting pixels in adjacent rows are staggered by one pixel position in the column direction (i.e., arranged in a "honeycomb" or "diamond" shape). Specifically, the driving backplane has M rows × N columns of pixels, where M=480 and N=360.

[0103] The center of pixels in odd-numbered rows is located at integer column coordinates, while the center of pixels in even-numbered rows is located between the two adjacent columns (i.e., offset by half a pixel spacing). The misalignment of pixels in adjacent rows in the column direction is 1 / 2 the width of one pixel.

[0104] The advantages of this staggered arrangement are: it improves the uniformity of spatial light distribution and reduces moiré fringes caused by periodic structures; it increases the physical distance between adjacent rows of pixels at the same pixel density, reducing inter-row crosstalk; and it is beneficial for the homogenization processing of the subsequent scattering layer, further improving the uniformity of light output.

[0105] Optical simulation and actual measurement show that, compared with the traditional grid arrangement, the light output uniformity (characterized by brightness non-uniformity) of the device with staggered arrangement is reduced from 15% to 8%, and the communication error rate is not significantly degraded.

[0106] In this embodiment, the patterning of the interface charge generation layer is further performed using one of the following processes:

[0107] The high-precision mask uses a metal mask with its opening position precisely aligned with the light-emitting region of the gallium nitride-based micron-sized light-emitting diode subunit. The mask processing accuracy is ±1μm.

[0108] The laser direct writing process, after depositing a complete interface charge generation layer, uses a 355nm nanosecond laser direct writing system. The computer controls the focused spot to ablate and remove the interface charge generation layer in the non-light-emitting area, while retaining the light-emitting area. The patterning accuracy also reaches ±1μm.

[0109] Both processes can achieve precise coverage of the light-emitting region of the micron-sized LED subunit by the interface charge generation layer, avoiding leakage and optical crosstalk between pixels. Scanning electron microscopy verification shows that the patterned edge roughness is less than 100 nm, and the alignment deviation is within ±0.8 μm, meeting the accuracy requirement of ±1 μm.

[0110] Furthermore, in some embodiments of this application, the basic units in the diode panel are disclosed to emit RGB three-color light and white light, and can also form an m×n pixel matrix. An array driving circuit is used to form a display screen capable of displaying images from this pixel matrix. The display screen driving circuit can refer to existing LED display screen drivers.

[0111] Although preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present application.

[0112] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0113] The above provides a detailed description of a high-bandwidth light-emitting diode, its fabrication method, and a lighting system provided in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are intended to help understand the method and core ideas of this application. At the same time, those skilled in the art will recognize that there may be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A high-bandwidth light-emitting diode, characterized in that, include: Drive backplane; as well as Multiple light-emitting pixels are disposed on the driving backplate, each of the light-emitting pixels being a vertically stacked hybrid light-emitting unit, the hybrid light-emitting unit comprising: A first electrode is formed on the drive backplate; A gallium nitride-based micron-sized light-emitting diode subunit is formed on the first electrode and is used to emit light of a first wavelength. The lateral dimension of the gallium nitride-based micron-sized light-emitting diode subunit is 5-50 μm. An interface charge generation layer is formed on the light-emitting side of the gallium nitride-based micron light-emitting diode subunit, comprising a transparent conductive oxide layer, a first charge generation sublayer, and a second charge generation sublayer stacked sequentially. An organic light-emitting diode subunit is formed on the interface charge generation layer and is used to emit light of a second wavelength, which is different from the first wavelength. The second electrode is formed on the organic light-emitting diode subunit; The driving backplate is connected to the first electrode and the second electrode via wires, and is used to independently control the luminous intensity of the gallium nitride-based micron-sized light-emitting diode subunit and the organic light-emitting diode subunit in each of the light-emitting pixels.

2. The high-bandwidth light-emitting diode according to claim 1, characterized in that, The peak emission wavelength of the gallium nitride-based micron-sized light-emitting diode subunit is 450-480 nm; The organic light-emitting diode subunit is a phosphorescent organic light-emitting diode or a thermally activated delayed fluorescence organic light-emitting diode, and its emission spectrum includes at least one wavelength component longer than 500 nm to achieve spectral complementarity with the gallium nitride-based micron light-emitting diode subunit to form white light.

3. The high-bandwidth light-emitting diode according to claim 1, characterized in that, In the interface charge generation layer: The transparent conductive oxide is indium tin oxide or indium zinc oxide, with a thickness of 50-200 nm. The first charge-generating sublayer is a HAT-CN thin film with a thickness of 5-20 nm; The second charge-generating sublayer is an n-type doped organic electron transport material, wherein the n-type dopant is LiNH2, Cs2CO3 or Rb2CO3, and the organic electron transport material is Bphen, TPBi or TmPyPB.

4. The high-bandwidth light-emitting diode according to claim 1, characterized in that, The driving backplane is a silicon-based backplane containing complementary metal-oxide-semiconductor driving circuitry or a glass-based backplane containing thin-film transistor driving circuitry.

5. The high-bandwidth light-emitting diode according to claim 1, characterized in that, It also includes a scattering layer and / or a wavelength conversion layer covering the plurality of light-emitting pixels, used to homogenize and color correct the emitted light from the plurality of light-emitting pixels.

6. The high-bandwidth light-emitting diode according to claim 1, characterized in that, The plurality of light-emitting pixels are arranged in an array on the driving backplate, and two light-emitting pixels in adjacent rows are offset by one pixel in the column direction.

7. The high-bandwidth light-emitting diode according to claim 1, characterized in that, The gallium nitride-based micron-sized light-emitting diode subunit is a blue light emitting unit, and the organic light-emitting diode subunit is a white light compensation unit co-doped with red and green light. Under the independent control of the driving backplane, the gallium nitride-based micron-sized light-emitting diode subunit is loaded with a high-frequency communication modulation signal, and the organic light-emitting diode subunit is loaded with a DC or low-frequency illumination bias signal.

8. The high-bandwidth light-emitting diode according to claim 3, characterized in that, The HAT-CN film in the interface charge generation layer reduces the root mean square roughness of the transparent conductive oxide surface to below 1 nm and increases the effective work function of the transparent conductive oxide by at least 0.3 eV.

9. A method for fabricating a light-emitting diode according to any one of claims 1 to 8, characterized in that, Includes the following steps: Step 1: Fabricate a patterned first electrode on the driving backplane; Step 2: An array of gallium nitride-based micron-sized light-emitting diode subunits is fabricated on the first electrode through epitaxial growth, photolithography, and etching processes. The mesa of each gallium nitride-based micron-sized light-emitting diode subunit is isolated by a silicon dioxide layer. Step 3: Deposit and pattern an interface charge generation layer on the entire device surface, ensuring that it only covers the light-emitting region of the gallium nitride-based micron-sized light-emitting diode subunit; Step 4: Sequentially deposit each organic functional layer of the organic light-emitting diode subunit and the second electrode on the interface charge generation layer using a vacuum thermal evaporation process. Step 5: Lead the first and second electrodes of all light-emitting pixels to the driving circuit through the wires on the driving backplate.

10. A lighting system, characterized in that, Includes a high-bandwidth light-emitting diode as described in any one of claims 1 to 8, and connected thereto: Power supply and control module for providing lighting drive and communication modulation signals; A photoelectric detection and demodulation module for receiving visible light signals emitted by the light-emitting diode and converting them into electrical signals.

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