A self-powered up-conversion imaging array and method of fabrication thereof

Abstract

The application relates to the field of semiconductor optoelectronics, in particular to a self-powered up-conversion imaging array and a preparation method thereof. The technical key points are as follows: array pixel units are arranged on an insulating substrate and are mutually isolated; each unit contains a central up-conversion detection subunit and a peripheral photovoltaic power supply subunit; the photovoltaic unit is formed by connecting micro photovoltaic cells in series, and the anode and the cathode are connected with the cathode and the anode of the central up-conversion detection subunit respectively, so as to form an independent closed loop series driving circuit in the pixel; the central up-conversion detection subunit is used for receiving incident near-infrared light signals and converting the signals into visible light signals; the peripheral photovoltaic power supply subunit is used for absorbing incident light and converting the light energy into electric energy to provide a driving voltage and a driving current; the peripheral photovoltaic power supply subunit and the central up-conversion detection subunit meet the current matching condition; the effects of self-power supply at the pixel level, complete elimination of electrical crosstalk between pixels, improvement of imaging contrast and resolution, improvement of photon utilization rate and device fault tolerance are achieved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronics technology, specifically to a self-powered upconversion imaging array and its fabrication method. Background Technology

[0002] Near-infrared light (wavelength 700-2500 nm) carries a wealth of crucial information that is inaccessible to the human eye due to its excellent penetrating power through smoke, silicon wafers, and biological tissues. Therefore, near-infrared imaging technology holds an irreplaceable strategic position in fields such as night vision security monitoring, semiconductor chip internal defect detection, biomedical imaging, and optical communication spot calibration. However, because the human eye is insensitive to this wavelength, it must be converted into a visible image using photoelectric conversion devices.

[0003] Current infrared imaging technologies primarily rely on inorganic semiconductor detectors (such as Si, InGaAs, and HgCdTe) or rare-earth-doped luminescent materials, but both have significant limitations: Inorganic detector arrays, while highly sensitive, must be interconnected with the back-end readout circuit (ROIC) via indium pillar flip-chip bonding and require an external display. Their fabrication process is complex and costly, and the devices are rigid, making them unsuitable for flexible wearable applications. Rare-earth upconversion materials, while possessing naturally passive properties, suffer from low quantum efficiency due to nonlinear optical processes, making it difficult to detect weak signals and exhibiting slow response times.

[0004] In contrast, organic / inorganic hybrid semiconductor upconversion devices employ an integrated stacked structure of a photodetector and a light-emitting diode (LED) directly connected in series. This enables direct conversion of infrared photons to visible photons without requiring complex readout circuits or external display terminals, offering significant advantages such as simple structure, large-area fabrication capability, high flexibility, and excellent imaging linearity. Although up-conversion devices have great potential, current mainstream research is still focused on "large-area single-unit devices" or "continuous thin-film structures." Such structures face two major technical bottlenecks in practical applications: (1) Poor reliability and blurring of images in large-area single-unit structures: Most existing devices are based on a "sandwich" structure of full-area electrodes, which has a shortcoming in reliability: This large-area single-unit structure is extremely sensitive to tiny defects in the fabrication process. Once there is even a tiny pinhole or short circuit in the large-area thin film, the current will preferentially pass through the low-resistance channel, causing the voltage of the entire device to be pulled down and unable to work, that is, "one point of damage, the whole device fails", which greatly reduces the yield and service life of the device; secondly, imaging crosstalk: In the full-area structure, photogenerated carriers are prone to diffuse in the lateral transport layer, resulting in blurring of the light spot edge; and it is impossible to physically isolate the signal, making it difficult to achieve high-contrast spatial resolution imaging. (2) Dependence on external power supply: The working principle of up-conversion devices determines that they must rely on an external electric field to assist in the separation and injection of carriers. Therefore, existing devices must be connected to an external DC power supply or battery through wires. Application limitations: The presence of external power supply and drive circuitry not only significantly increases the size and weight of the system, compromising the flexibility and portability of the device, but also makes it difficult to apply the device in fields with extremely high requirements for lightweighting, such as untethered scenarios, implantable medical devices, or electronic skin.

[0005] In summary, there is a need to develop a new type of self-powered array-based upconversion imaging device that can solve the reliability problem of large-area single devices where "a change in one part affects the whole system" and also eliminate dependence on external power sources. Summary of the Invention

[0006] To address the aforementioned shortcomings of existing technologies, this invention provides a self-powered upconversion imaging array and its fabrication method. This effectively solves the technical problems of single-point defects leading to overall failure in large-area upconversion devices in existing upconversion technologies, as well as external power supply dependence and inter-pixel electrical crosstalk encountered in array applications.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] In a first aspect, the present invention provides a self-powered upconversion image array, comprising: an insulating substrate, and a plurality of pixel units arranged in an array on the same plane of the insulating substrate;

[0009] The pixel units are independently distributed through physical or electrical isolation;

[0010] The pixel unit is divided into a central upconversion detection subunit and an outer photovoltaic power supply unit;

[0011] The central upconversion detector subunit is located in the central region of the pixel unit and is used to receive the incident near-infrared light signal and convert it into a visible light signal.

[0012] The peripheral photovoltaic power supply unit is located in the region at the edge of the pixel unit and distributed around the central upconversion detection subunit. It is used to absorb incident light and convert light energy into electrical energy to provide the driving voltage and current required for the operation of the central upconversion detection subunit.

[0013] The positive and negative terminals of the peripheral photovoltaic power supply unit are electrically connected to the anode and cathode of the central upconversion detection subunit, respectively, forming an independent closed-loop series drive circuit within a single pixel unit.

[0014] Furthermore, the insulating substrate is a rigid insulating substrate or a flexible insulating substrate; the rigid insulating substrate is selected from glass, quartz, sapphire, ceramic substrate or silicon wafer with an insulating layer on the surface; the flexible insulating substrate is selected from polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI) or flexible ultrathin glass.

[0015] Furthermore, the peripheral photovoltaic power supply unit and the central upconversion detection subunit satisfy the current matching condition;

[0016] The current matching condition is that, under the target incident light illumination condition, the output current value of the micro photovoltaic cell connected in series in the peripheral photovoltaic power supply unit must be greater than or equal to the operating current value of the central upconversion detection subunit under the preset luminous brightness, so as to ensure that the operating current of the upconversion detection subunit is not limited by the photovoltaic power supply unit.

[0017] Furthermore, the peripheral photovoltaic power supply unit is composed of multiple micro photovoltaic cells connected in series;

[0018] The number n of the micro photovoltaic cells connected in series satisfies the formula:

[0019] n×V offer ≥V th ;

[0020] Among them, Voffer V is the open-circuit voltage of a single micro photovoltaic cell under the target incident light intensity. th The operating voltage required for the central upconversion detection subunit to achieve a preset luminous brightness.

[0021] Furthermore, the planar geometry of the peripheral photovoltaic power supply unit includes a frame shape, a ring shape, or a U-shape, forming a fully or semi-enclosed distribution around the central upconversion detection subunit.

[0022] Furthermore, the multiple micro photovoltaic cells are physically divided within the annular or frame-shaped region by laser etching or photolithography, and are connected in series end to end by a deposited or sputtered conductive interconnect layer.

[0023] Furthermore, the peripheral photovoltaic power supply unit adopts an organic photovoltaic structure compatible with the upconversion detection subunit process;

[0024] The central upconversion detector subunit adopts an organic or inorganic hybrid stacked structure, which includes, in sequence: an anode, an electron extraction layer, a near-infrared photosensitive layer, an electron blocking-hole transport layer, a light-emitting layer, an electron transport-hole blocking layer, an electron injection layer, and a cathode.

[0025] The micro photovoltaic cell comprises, in sequence, an anode, an electron transport layer, a photoactive layer, a hole transport layer, and a cathode.

[0026] Furthermore, the physical isolation is achieved through a pixel isolation structure, which is a physical trench formed by an etching process.

[0027] And / or, a pixel definition layer formed by photolithographic insulating adhesive is used to block the lateral diffusion of charge carriers between adjacent pixel units and eliminate electrical crosstalk between pixels;

[0028] The electrical isolation is a local high-impedance region formed between adjacent pixel units by ion implantation, and / or a spatial electric field isolation region formed by retaining the continuity of the organic functional layer only by patterning the top and bottom electrodes.

[0029] Furthermore, both the near-infrared photosensitive layer and the photoactive layer comprise a solution-processable narrow bandgap semiconductor material, selected from one or more combinations of organic semiconductor materials, colloidal quantum dot materials, or perovskite material systems.

[0030] The organic semiconductor material is selected from PM6:Y6, PM6:BTP-eC9, PTB7-Th:IEICO-4F or its derivatives;

[0031] The colloidal quantum dot material is selected from lead sulfide (PbS), lead selenide (PbSe), mercury telluride (HgTe), or their core-shell structure quantum dots.

[0032] The perovskite material is selected from two-dimensional or three-dimensional hybrid perovskites, lead-based perovskites, or tin-based perovskites.

[0033] The luminescent layer comprises organic fluorescent materials, organic phosphorescent materials, thermally activated delayed fluorescent materials, quantum dot luminescent materials, or perovskite luminescent materials.

[0034] Furthermore, the size of the pixel unit is less than or equal to the diffraction-limited spot size of the optical system or the expected minimum target spot size.

[0035] Secondly, the present invention provides a method for fabricating a self-powered upconversion imaging array based on pixel-level photovoltaic surround drive, comprising the following steps:

[0036] A bottom electrode array was fabricated on an insulating substrate using magnetron sputtering and patterning processes.

[0037] Using solution spin coating or vacuum evaporation processes, combined with mask or photolithography processes, an upconversion functional layer and a photovoltaic functional layer are respectively prepared in the central region and the peripheral region of each pixel unit.

[0038] By using laser scribing or fine metal mask deposition processes, a series interconnection structure of micro photovoltaic cells is constructed in the peripheral area, and the connection between the positive and negative electrodes of the photovoltaic units and the anode and cathode of the central upconversion unit is completed simultaneously.

[0039] A top electrode is deposited and an encapsulation layer is fabricated to form a complete self-powered upconversion imaging array device.

[0040] Furthermore, the bottom electrode and top electrode are made of one or more of metals, metal oxides and graphene, and the electrodes are transparent, translucent or opaque.

[0041] The technical solution provided by this invention has the following advantages compared with the known prior art:

[0042] 1. The self-powered upconversion imaging array provided by the present invention sets up independent pixel units on the same plane of an insulating substrate. Each pixel unit integrates a central upconversion detector subunit and an outer photovoltaic power supply unit. The positive and negative terminals of the photovoltaic power supply unit are electrically connected to the anode and cathode of the upconversion detector subunit, respectively. An independent closed-loop series driving circuit is formed within a single pixel, realizing pixel-level independent closed-loop self-powering. This completely eliminates the need for external power supplies, driving circuits, and physical leads, freeing the device from dependence on external energy. Photogenerated carriers are strictly confined to the micron-level pixel boundary for circulation and recombination. This means that voltage fluctuations in bright pixels will never lower or interfere with the potential of adjacent dark pixels, eliminating electrical crosstalk between pixels and ensuring high spatial resolution and high contrast in imaging.

[0043] 2. This invention limits the current matching conditions between the peripheral photovoltaic power supply unit and the central upconversion detection subunit, and ensures that the number of micro-photovoltaic cells connected in series satisfies n×V. offer ≥V th The requirements ensure that the voltage output of the photovoltaic power supply unit is sufficient to drive the upconversion detection subunit to start working, and that the output current does not limit its upconversion operation. This achieves precise matching of energy conversion and signal conversion within the pixel, ensuring that the upconversion detection subunit works stably and efficiently under the preset luminous brightness, and improving the photon utilization efficiency of the device and the brightness stability of the imaging.

[0044] 3. The peripheral photovoltaic power supply unit of the present invention adopts a frame-shaped, ring-shaped, or U-shaped fully enclosed / semi-enclosed structure, and the pixel units are separated by physical trenches and pixel definition layers to form a pixel isolation structure. On the one hand, this allows the photovoltaic power supply unit to absorb incident light energy more efficiently, improve the conversion efficiency of light energy to electrical energy, and provide sufficient energy for upconversion. On the other hand, it effectively blocks the lateral diffusion of charge carriers between adjacent pixels, further eliminates electrical crosstalk, and makes the structural design of the pixel unit more suitable for arrayed arrangement, thereby improving the spatial resolution of the array.

[0045] 4. This invention discretizes large-area devices into tens of thousands of independent micro-pixel units. Even if individual pixels are short-circuited or damaged due to manufacturing process reasons, the impact is limited to that single pixel (manifested as a single black dot) and will not affect surrounding pixels or cause the overall circuit to fail. This highly reliable array architecture significantly improves the yield of large-area devices and extends the service life of the devices.

[0046] 5. This invention can complete all functional layer structures on a single-layer flexible substrate through low-cost solution processing or patterning processes (monolithic integration), completely eliminating the complex TFT active driving backplane and all external physical leads. The structure is extremely simple. This minimalist structure of "passive, wireless, and backplane-free" makes the array very easy to fabricate into ultra-thin and ultra-light "electronic skin" or "wearable infrared detection patch", perfectly meeting the needs of biomimetic sensing and IoT portable devices. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0048] Figure 1Schematic diagram of the overall array structure of the self-powered upconversion array of the present invention (taking 7×11 as an example);

[0049] Figure 2 Schematic diagram of a single pixel unit in the present invention;

[0050] Figure 3 Schematic diagram of the "6" imaging of the array plane composed of 20×20 circular pixel units in the present invention;

[0051] Figure 4 Schematic diagram of the device structure of the "field" - shaped pixel unit in Embodiment 1 of the present invention;

[0052] Figure 5 Schematic diagram of the subunit structure of the photovoltaic cell in Embodiment 1 of the present invention;

[0053] Figure 6 Schematic diagram of the device structure of the upconversion unit in Embodiment 1 of the present invention;

[0054] [[ID=2(3]] Figure 7 Physical diagram of the self-powered operation under 850 nm infrared light in Embodiment 1 of the present invention. Detailed implementation manners

[0055] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention.

[0056] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail. Regarding the terms "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to. Unless otherwise clearly stated in the context, the expressions "a" and "an" used herein include plural references. It should be noted that "first", "second", etc. are only for convenience of description and easy distinction, and cannot be construed as indicating or implying relative importance. The term "about" used herein means a range of ±20% of the value following it. In some embodiments, the term "about" means a range of ±10% of the value following it. In some embodiments, the term "about" means a range of ±5% of the value following it. The present invention will be further described below with reference to the embodiments.

[0057] Example: Refer to Figures 1 to 7 .

[0058] The self-powered upconversion array provided by this invention is a self-powered upconversion imaging array based on pixel-level photovoltaic surround drive, such as... Figure 1 As shown, an example of an overall array structure (7×11) is presented. This device achieves high-resolution infrared visualization imaging without external power supply and without pixel crosstalk by constructing an independent "photovoltaic surround-upconversion center" closed-loop system within each micrometer-level pixel.

[0059] Specifically, the self-powered upconversion imaging array includes an insulating substrate and multiple pixel units arranged in an array on the insulating substrate. The pixel units are physically or electrically isolated to form independent micro-elements. Each pixel unit includes two independent functional regions in its planar structure: a peripheral region and a central region. The central region is a central upconversion detection subunit, used to receive near-infrared light signals from the target and perform upconversion emission, realizing the detection and display imaging functions of near-infrared light. The peripheral region is a peripheral photovoltaic power supply unit, arranged in a ring or frame structure around the upconversion detection subunit, or adjacent to the upconversion detection subunit (e.g., ...). Figure 2 As shown, only one example is presented.

[0060] Physical isolation is achieved through pixel isolation structures, which are physical trenches formed by etching processes and / or pixel definition layers formed by photolithographic insulating adhesives. These structures block the lateral diffusion of charge carriers between adjacent pixel units and eliminate electrical crosstalk between pixels. Electrical isolation is achieved through localized high-impedance regions formed between adjacent pixel units by ion implantation processes and / or through spatial electric field isolation regions formed by patterning disconnections of the top and bottom electrodes while maintaining the continuity of the organic functional layers. The pixel definition layer (PDL) is a very typical physical isolation method in the field of semiconductor optoelectronic displays. It typically consists of physical banks formed by photolithographic insulating adhesives (such as polyimide PI), which physically isolate the light-emitting or photosensitive regions of each pixel, thereby effectively blocking the lateral diffusion of charge carriers between adjacent pixels.

[0061] Circuit connection and driving mechanism: The peripheral photovoltaic power supply unit is composed of multiple micro photovoltaic cells (sub-cells) connected in series end to end inside the pixel to form a high-voltage output ring power supply; the positive terminal (high potential output terminal) of the peripheral photovoltaic power supply unit is electrically connected to the anode of the central upconversion detection sub-unit; the negative terminal (low potential output terminal) of the peripheral photovoltaic power supply unit is electrically connected to the cathode of the central upconversion detection sub-unit; thus, an independent, closed-loop "photovoltaic-upconversion" series driving circuit is formed inside each pixel unit.

[0062] The self-driven working principle of the self-powered upconversion image array of this invention is as follows:

[0063] Regarding the "light-energy-signal" collaborative working mechanism: This invention utilizes the incident light beam as both an "energy source" and a "signal source," achieving pixel-level adaptive light emission based on a current matching mechanism. On one hand, in the dark / no target light state: the pixel unit is in a light-free state, the peripheral photovoltaic power supply unit does not generate photogenerated voltage, and the central upconversion detector subunit is in a zero-bias cutoff state. Similarly, there is no infrared illumination on the upconversion device, and no photogenerated carriers. Therefore, the entire device is in a "dormant" mode, with no dark current noise and zero power consumption. On the other hand, in the bright / target light state: when the target near-infrared light spot illuminates the array, as long as the light spot area covers the pixel unit (i.e., simultaneously covering the peripheral photovoltaic ring and the central detector area), the incident light is efficiently utilized: some photons are absorbed by the peripheral photovoltaic ring, instantly establishing a high bias voltage through the photovoltaic effect; the other part of the photons are absorbed by the central detector area, achieving carrier injection and recombination light emission under the drive of the bias voltage.

[0064] Size matching design analysis of the self-powered upconversion image array device of this invention:

[0065] To ensure synchronous energy and signal conversion, the pixel unit size is designed to be smaller than or equal to the diffraction-limited spot size of the optical system or the expected minimum target spot size. This ensures that during imaging, any effective spot can simultaneously "activate" the photovoltaic ring and the detection center, avoiding blind spots such as "light without electricity" or "electricity without signal".

[0066] Analysis of the number of micro photovoltaic cells connected in series:

[0067] The number n of micro-photovoltaic cells connected in series in the peripheral photovoltaic power supply unit is determined by the operating turn-on voltage V of the central upconversion detection subunit. th With the open-circuit voltage V of a single photovoltaic cell offer It is determined that n×V offer ≥V th .

[0068] Current limiting effect analysis:

[0069] In the peripheral micro-region photovoltaic power supply unit, the number of micro-photovoltaic cells connected in series is n. The current in the series circuit is equal, meaning the current value of the entire closed loop is the minimum among all sub-units. Therefore, to ensure that the current of all sub-cells is minimized, I... limit The operating current value I of the upconversion subunit is greater than or equal to that of the upconversion subunit. work To prevent it from being throttled.

[0070] To facilitate demonstration of the effects of this invention patent, such as Figure 3 The diagram illustrates an array plane composed of 20×20 circular pixel units. The arrow in the upper left corner represents the incident near-infrared signal beam. This beam, modulated by a mask or spatial light modulator, carries the pattern information of the number "6" and is projected onto the array surface. The area covered by the light spot shaped like the number "6" corresponds to the pixel region. Due to the pixel-level self-powered mechanism of this invention, the photovoltaic rings within these pixels absorb light energy to generate a bias voltage, simultaneously driving the central detection unit to output a visible light signal (represented by solid black dots indicating the lit state). The area corresponding to the background region not illuminated by the light spot corresponds to the background region. Due to the lack of incident light energy, these pixel units are in a zero-bias sleep state and do not emit light (represented by hollow circles indicating the off state).

[0071] Figure 3 This invention visually demonstrates the excellent spatial resolution and pixel-independent addressing capabilities of its array, and illustrates that the device requires no external power supply, making it a self-driven device. The light-receiving area emits light precisely, while the non-light-receiving area is completely blocked, with no electrical crosstalk between pixels, achieving high-contrast, high-fidelity in-situ visualization imaging of incident infrared patterns.

[0072] Traditional pixel-free isolation structures or globally powered arrays often face severe crosstalk problems: photogenerated carriers from bright pixels diffuse into dark pixel regions, lowering the potential of dark pixels and causing image blurring. This invention employs a "pixel-level independent power supply circuit" design. Each pixel unit has a completely independent micro power supply and load circuit. Photogenerated carriers are strictly confined to the micrometer-level pixel boundary for circulation and recombination. This means that voltage fluctuations in bright pixels will never lower or interfere with the potential of neighboring dark pixels, thus completely solving the electrical crosstalk problem in array imaging and ensuring high spatial resolution and high contrast in imaging through a physical mechanism.

[0073] The prior art usually requires an external power supply to provide a bias voltage to drive the device, with low energy utilization efficiency and a complex system. The present invention innovatively proposes the concept of "Source-Driven". The incident near-infrared light beam is given a dual role: it is both the "information source" to be detected and the "energy source" to drive the device to work. Through the in-pixel micro-region series structure, efficient in-situ conversion and utilization of the incident light energy are achieved. This mechanism enables the device to directly visualize near-infrared light signals without any external power supply and without the assistance of background light, truly achieving "lighting up when there is light and turning off when there is no light", realizing the perfect integration of "energy" and "information" and maximizing the photon utilization rate.

[0074] Considering that in large-area continuous thin-film devices, any tiny pinhole or fabrication defect may cause a whole-device short circuit, resulting in a "completely black" failure and a very low yield. The present invention discretizes the large-area device into tens of thousands of mutually independent tiny pixel units. Even if individual pixels are short-circuited or damaged due to the fabrication process, the impact is only limited to that single pixel point (manifested as a single black dot), and it will never affect the surrounding pixels or cause the overall circuit to break down. This highly reliable array architecture significantly improves the fabrication yield of large-area devices and extends the service life of the device.

[0075] Traditional infrared focal plane arrays rely on expensive and rigid readout integrated circuits (ROICs) or thin-film transistor (TFT) active backplanes, and require complex wire bonding and packaging, making it difficult to achieve flexibility. The present invention completely abandons the complex TFT active driving backplane and all external physical leads. The structure is extremely simple, and all functional layer structures of the central upconversion detection sub-unit and the peripheral micro-region photovoltaic power supply sub-unit can be completed on a single-layer flexible substrate through low-cost solution processing or patterning processes (monolithic integration). This "passive, wireless, and backplane-free" minimalist structure makes it extremely easy to fabricate this array into an ultra-thin and ultra-light "electronic skin" or "wearable infrared detection patch", perfectly meeting the requirements of bionic sensing and Internet of Things portable devices.

[0076] Example 1

[0077] This example provides a homogeneous integrated self-powered upconversion pixel unit based on a "field" - shaped four-quadrant splicing, specifically as follows:

[0078] Device structure design: In this example, a large-area self-powered upconversion pixel verification unit was fabricated, as shown in Figure 4As shown, the pixel unit is composed of 4 square sub-regions with equal area spliced together to form a large square in a planar geometric structure (similar to the Chinese character "field" structure). Sub-region division: 3 of the 4 sub-regions are defined as micro photovoltaic cells (PVSub-cells), and the remaining 1 is defined as the central up-conversion detection unit.

[0079] Area parameter: The area of each square sub-region is 0.1 cm 2 (i.e., 3.16 mm × 3.16 mm). The total area of the entire pixel unit is 0.69 cm 2 .

[0080] Connection topology: For the convenience of testing, 3 micro photovoltaic cells are connected in series head-to-tail through alligator clips and wires to form a series photovoltaic module. The positive pole of this module is connected to the anode of the up-conversion detection unit, and the negative pole is connected to the cathode of the up-conversion detection unit to form a closed-loop drive circuit.

[0081] Device materials and layer structure To verify the feasibility of homogeneous integration, both the photovoltaic unit and the up-conversion unit use the same narrow-bandgap organic semiconductor as the photoactive material.

[0082] The specific layer structure, layer energy composition materials and thickness are as follows:

[0083] (1) Indoor photovoltaic cell structure:

[0084] As Figure 5 shown, it includes an anode: indium tin oxide (ITO) glass; an electron transport layer: zinc oxide (ZnO) nanoparticles with a thickness of 30 nm; a photoactive layer: PM6:BTP-eC9 (weight ratio 1:1.2) with a thickness of 100 nm; a hole transport layer: molybdenum oxide (MoO3) with a thickness of 10 nm; a cathode: silver (Ag) with a thickness of 100 nm.

[0085] (2) Central up-conversion detection unit structure:

[0086] As Figure 6As shown, the anode is indium tin oxide (ITO) glass; the electron extraction layer is zinc oxide (ZnO) nanoparticles, 30 nm thick; the near-infrared photosensitive layer is PM6:BTP-eC9 (weight ratio 1:1.2), 100 nm thick; the electron blocking-hole transport layer is TAPC, 30 nm thick; the light-emitting layer is CBP:Ir(MDQ)2acac (red phosphorescent material), doped at 5 wt%, 30 nm thick; the electron transport-hole blocking layer is B3PyMPM, 40 nm thick; the electron injection layer is lithium fluoride (LiF), 1 nm thick; and the cathode is aluminum (Al), 100 nm thick. The ZnO / PM6:BTP-eC9 layer can be used to fabricate both the battery module and the central upconversion detection unit. The electron blocking-hole transport layer of the central upconversion detection unit of this invention can efficiently transport holes and effectively block electrons from leaking in the opposite direction in terms of energy level matching. The electron transport-hole blocking layer of the central upconversion detection unit can promote the efficient and smooth transport of electrons from the cathode to the light-emitting layer and effectively prevent holes from leaking from the light-emitting layer to the cathode, strictly confining the holes inside the light-emitting layer, and playing the roles of localization, anti-quenching, and regulating carrier balance.

[0087] Working principle verification and test results

[0088] The prepared pixel units were tested under a near-infrared light source to verify their self-driving characteristic of "operating upon illumination". Test conditions: The device surface was vertically illuminated using a near-infrared LED light source with a wavelength of 850 nm, and the incident light power density was controlled at 50 mW / cm². 2 .

[0089] Voltage matching analysis: Under this light intensity, the open-circuit voltage V generated by a single PM6:BTP-eC9 photovoltaic cell is... offer Approximately 0.9 V, with three sub-cells connected in series, the total drive voltage provided by the photovoltaic module is 2.7 V. The turn-on voltage V of the red-light upconversion device in this structure was tested separately. th The total drive voltage (2.7V) is approximately 1.6V, which is greater than the turn-on voltage (1.6V). Therefore, the voltage generated by the photovoltaic module is sufficient to overcome the barrier of the up-conversion device and drive it to emit light.

[0090] Lighting effect: such as Figure 7 The diagram shown depicts the self-powered prototype. Upon activation of 850 nm illumination, the upconversion region (1 / 4 area) within the pixel unit visibly emits bright red light. Luminance measurements indicate that the upconversion unit's luminance exceeds 50 cd / m². 2 .

[0091] Conclusion: This embodiment successfully verified that the topology of using three photovoltaic units in series to drive one upconversion unit of the same material can effectively absorb near-infrared light energy and drive the device to work. Although the size is relatively large (millimeter level), its "field" shaped splicing structure perfectly simulates the topological logic of a single pixel in the array, proving the feasibility of the pixel-level self-powered technology proposed in this invention in principle.

[0092] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A self-powered upconversion image array, characterized in that, include: An insulating substrate, and a plurality of pixel units arranged in an array on the same plane as the insulating substrate; The pixel units are independently distributed through physical or electrical isolation; The pixel unit is divided into a central upconversion detection subunit and an outer photovoltaic power supply unit; The central upconversion detector subunit is located in the central region of the pixel unit and is used to receive the incident near-infrared light signal and convert it into a visible light signal. The peripheral photovoltaic power supply unit is located in the region at the edge of the pixel unit and distributed around the central upconversion detection subunit. It is used to absorb incident light and convert light energy into electrical energy to provide the driving voltage and current required for the operation of the central upconversion detection subunit. The positive and negative terminals of the peripheral photovoltaic power supply unit are electrically connected to the anode and cathode of the central upconversion detection subunit, respectively, forming an independent closed-loop series drive circuit within a single pixel unit.

2. The self-powered upconversion imaging array according to claim 1, characterized in that, The peripheral photovoltaic power supply unit and the central upconversion detection subunit satisfy the current matching condition; The current matching condition is that, under the target incident light illumination condition, the output current value of the micro photovoltaic cell connected in series in the peripheral photovoltaic power supply unit must be greater than or equal to the operating current value of the central upconversion detection subunit under the preset luminous brightness, so as to ensure that the operating current of the upconversion detection subunit is not limited by the photovoltaic power supply unit.

3. A self-powered upconversion imaging array according to claim 1 or 2, characterized in that, The peripheral photovoltaic power supply unit consists of multiple micro photovoltaic cells connected in series. The number n of the micro photovoltaic cells connected in series satisfies the formula: n×V offer ≥V th ; Among them, V offer V is the open-circuit voltage of a single micro photovoltaic cell under the target incident light intensity. th The operating voltage required for the central upconversion detection subunit to achieve a preset luminous brightness.

4. A self-powered upconversion image array according to claim 1, characterized in that, The planar geometry of the peripheral photovoltaic power supply unit includes a frame shape, a ring shape, or a U-shape, forming a fully or semi-enclosed distribution around the central upconversion detector subunit.

5. A self-powered upconversion imaging array according to claim 3, characterized in that, The peripheral photovoltaic power supply unit adopts an organic photovoltaic structure compatible with the upconversion detection subunit process; The central upconversion detector subunit adopts an organic or inorganic hybrid stacked structure, which includes, in sequence: an anode, an electron extraction layer, a near-infrared photosensitive layer, an electron blocking-hole transport layer, a light-emitting layer, an electron transport-hole blocking layer, an electron injection layer, and a cathode. The micro photovoltaic cell comprises, in sequence, an anode, an electron transport layer, a photoactive layer, a hole transport layer, and a cathode.

6. A self-powered upconversion imaging array according to claim 1, characterized in that, The physical isolation is achieved through a pixel isolation structure, which is a physical trench formed by an etching process. And / or, a pixel definition layer formed by photolithographic insulating adhesive is used to block the lateral diffusion of charge carriers between adjacent pixel units and eliminate electrical crosstalk between pixels; The electrical isolation is a localized high-impedance region formed between adjacent pixel units through an ion implantation process. And / or, isolation is achieved solely by preserving the spatial electric field isolation region formed by the continuity of the organic functional layer through patterned disconnection of the top and bottom electrodes.

7. A self-powered upconversion imaging array according to claim 5, characterized in that, Both the near-infrared photosensitive layer and the photoactive layer comprise a solution-processable narrow bandgap semiconductor material, selected from one or more combinations of organic semiconductor materials, colloidal quantum dot materials, or perovskite material systems. The organic semiconductor material is selected from PM6:Y6, PM6:BTP-eC9, PTB7-Th:IEICO-4F or its derivatives; The colloidal quantum dot material is selected from lead sulfide (PbS), lead selenide (PbSe), mercury telluride (HgTe), or their core-shell structure quantum dots. The perovskite material is selected from two-dimensional or three-dimensional hybrid perovskites, lead-based perovskites, or tin-based perovskites. The luminescent layer comprises organic fluorescent materials, organic phosphorescent materials, thermally activated delayed fluorescent materials, quantum dot luminescent materials, or perovskite luminescent materials.

8. A self-powered upconversion imaging array according to claim 1, characterized in that, The size of the pixel unit is less than or equal to the diffraction-limited spot size of the optical system or the expected minimum target spot size.

9. A method for fabricating a self-powered upconversion image array, characterized in that, Includes the following steps: A bottom electrode array was fabricated on an insulating substrate using magnetron sputtering and patterning processes. Using solution spin coating or vacuum evaporation processes, combined with mask or photolithography processes, an upconversion functional layer and a photovoltaic functional layer are respectively prepared in the central region and the peripheral region of each pixel unit. By using laser scribing or fine metal mask deposition processes, a series interconnection structure of micro photovoltaic cells is constructed in the peripheral area, and the connection between the positive and negative electrodes of the photovoltaic units and the anode and cathode of the central upconversion unit is completed simultaneously. A top electrode is deposited and an encapsulation layer is fabricated to form a complete self-powered upconversion imaging array device.

10. The method for fabricating a self-powered upconversion imaging array according to claim 9, characterized in that, The bottom and top electrodes are made of one or more of metals, metal oxides, and graphene, and the electrodes are transparent, semi-transparent, or opaque.

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