Colloidal quantum dot functional layer preparation method, photoelectric device and imaging sensor

Abstract

The invention provides a preparation method of a colloidal quantum dot functional layer, a photoelectric device and an imaging sensor. The silicon-based focal plane imaging sensor comprises a silicon-based reading circuit; the photoelectric device is integrated on the silicon-based readout circuit and comprises a top electrode for receiving optical signals, a bottom electrode attached to the silicon-based readout circuit and a colloidal quantum dot functional layer located between the top electrode and the bottom electrode; the colloidal quantum dot functional layer comprises m sizes of colloidal quantum dots, the m sizes are 4.5 nm to 8.2 nm, the range of first exciton absorption peaks of the m sizes of colloidal quantum dots is 1 [mu] m to 3 [mu] m, and the colloidal quantum dots of the same size are distributed in an array at preset positions on the silicon-based readout circuit.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a method for preparing a colloidal quantum dot functional layer, a photoelectric device, and a silicon-based focal plane imaging sensor. Background Art

[0002] Crystalline silicon-based materials have very low absorption efficiency in the near-infrared wavelength range, especially for short-wave infrared light above 1000 nanometers, for which silicon-based materials are almost transparent. Therefore, the external quantum efficiency of existing silicon-based photoelectric sensors in the short-wave infrared spectral range is very low and cannot effectively detect the short-wave infrared spectral range.

[0003] To address this problem, the existing commercial solution is to use III-V-InGaAs photosensitive materials to prepare short-wave infrared focal plane imaging sensors. The InGaAs focal plane imaging sensor has a photosensitive range of about 800nm ​​(nanometers)-1700nm, so it can be used as a broadband short-wave infrared focal plane imaging sensor.

[0004] However, InGaAs imaging sensors have the following main disadvantages: 1) They have weak absorption of visible light, making it difficult to achieve full coverage of visible light; 2) They cannot be grown epitaxially on a silicon substrate, but need to be grown epitaxially on an InP substrate at high temperature to produce InGaAs-based detectors; however, the preparation of InGaAs epitaxy on large-area InP wafers is very complex and costly; 3) Then, the InGaAs detector after epitaxial growth needs to be integrated with a silicon-based readout circuit by flip-chip bonding. Therefore, the InGaAs detector cannot be monolithically integrated with the existing silicon-based readout circuit, making mass production difficult; 4) At the same time, during the flip-chip bonding process, the size of the solder block directly determines the spacing between each pixel in the InGaAs imaging sensor, fundamentally limiting the pixel size of the sensor.

[0005] Based on the above points, the industry needs a low-cost, high external quantum efficiency broadband imaging solution from visible light to short-wave infrared. Summary of the invention

[0006] In order to solve the existing technical problems, the present application provides a low-cost silicon-based focal plane imaging sensor that can achieve a wide spectrum from visible light to short-wave infrared light and full coverage of high external quantum efficiency, a method for preparing a colloidal quantum dot functional layer, and an imaging device.

[0007] In a first aspect, a silicon-based focal plane imaging sensor is provided, comprising:

[0008] Silicon-based readout circuit;

[0009] An optoelectronic device, integrated on the silicon-based readout circuit, the optoelectronic device comprising a top electrode for receiving an optical signal, a bottom electrode attached to the silicon-based readout circuit, and a colloidal quantum dot functional layer located between the top electrode and the bottom electrode;

[0010] The colloidal quantum dot functional layer contains colloidal quantum dots of m sizes, wherein the m sizes are between 4.5 nm and 8.2 nm, and the first exciton absorption peak range of the m sizes of the colloidal quantum dots is between 1 μm and 3 μm. Each colloidal quantum dot of the same size is distributed in an array at a preset position on the silicon-based readout circuit.

[0011] In a second aspect, a method for preparing a colloidal quantum dot functional layer is provided, wherein the colloidal quantum dot functional layer comprises colloidal quantum dots of m sizes, wherein the m sizes are between 4.5 nm and 8.2 nm, and the first exciton absorption peak range of the m sizes of the colloidal quantum dots is between 1 μm and 3 μm, comprising:

[0012] According to the distribution of pixels on the focal plane of the imaging sensor, colloidal electron dots of m sizes are preset to correspond to the m array areas respectively;

[0013] Selecting colloidal quantum dots of a first size as a target size, and integrating them into a corresponding array area on a focal plane through a one-time integration preparation step; wherein the one-time integration preparation step includes integrating the colloidal quantum dots of the target size on the focal plane according to the array area corresponding to the distribution of the colloidal quantum dots of the target size;

[0014] Select the next size of colloidal quantum dots as the target size, and integrate them into the corresponding array area on the focal plane through an integration preparation step again. Repeat this step until the colloidal quantum dots of the mth size are integrated into the corresponding array area on the focal plane.

[0015] In a third aspect, a photoelectric device is provided, comprising a colloidal quantum dot functional layer prepared by the method for preparing a colloidal quantum dot functional layer described in any embodiment of the present application.

[0016] In the silicon-based focal plane imaging sensor provided by the above embodiment, the optoelectronic device is integrated on the silicon-based readout circuit, the optoelectronic device includes a colloidal quantum dot functional layer, the colloidal quantum dot functional layer includes colloidal quantum dots of m sizes, the m sizes are between 4.5nm and 8.2nm, the first exciton absorption peak range of the m sizes of colloidal quantum dots is between 1μm and 3μm, and each colloidal quantum dot of the same size is distributed in an array at a preset position on the silicon-based readout circuit. In this way, by integrating m colloidal quantum dots of different sizes into the preset position of the silicon-based readout circuit, Moreover, the positions of colloidal quantum dots of various sizes integrated on the silicon-based readout circuit can be distributed according to a preset array, forming a preset and fixed correspondence with the pixel distribution on the focal plane of the imaging sensor, eliminating the flip-chip bonding process, making wafer-level mass production of silicon-based focal plane imaging sensors based on colloidal quantum dots possible, thereby reducing costs and improving the uniformity of light signals absorbed by colloidal quantum dots, which is beneficial to improving imaging quality. The high absorption characteristics of different first exciton peaks of different colloidal quantum dots can achieve full coverage of a wide spectrum from visible light to short-wave infrared and high quantum efficiency.

[0017] The preparation method of the colloidal quantum dot functional layer and the optoelectronic device provided in the above embodiments belong to the same technical concept as the silicon-based focal plane imaging sensor embodiment, and thus have the same technical effect as the silicon-based focal plane imaging sensor embodiment, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a graph showing the corresponding relationship between the absorption spectra of colloidal quantum dots of various sizes and the first exciton peak.

[0019] Figure 2 Schematic diagram of the external quantum effect of colloidal quantum dots of a single size.

[0020] Figure 3 Schematic diagram of the external quantum effect of colloidal quantum dots of different sizes.

[0021] Figure 4 Schematic diagram of the structure of a silicon-based focal plane imaging sensor in one embodiment.

[0022] Figure 5 Schematic diagram of a colloidal quantum dot functional layer in one embodiment.

[0023] Figure 6 FIG. 4 is a schematic diagram of a colloidal quantum dot functional layer in another embodiment.

[0024] Figure 7 Flow chart of a method for preparing a colloidal quantum dot functional layer in one embodiment. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0026] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings. The described embodiments should not be regarded as limiting the present application. All other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of this application.

[0027] In the following description, the expression "some embodiments" is involved, which describes a subset of all possible embodiments. It should be noted that "some embodiments" may be the same subset or different subsets of all possible embodiments, and may be combined with each other without conflict.

[0028] In the study of how to achieve a low-cost, high external quantum efficiency broadband imaging solution from visible light to short-wave infrared, the inventors of this application conducted the following analysis on the confinement characteristics of colloidal quantum dots and the integration of colloidal quantum dots with silicon-based focal planes:

[0029] Colloidal quantum dots of new materials, including but not limited to lead sulfide, lead selenide, mercury telluride, indium arsenic, indium antimony, etc., can be synthesized in large quantities and at low cost at low temperature by solution processing. The synthesis methods may include but are not limited to cation exchange method, hot injection method, etc. Colloidal quantum dots have quantum confinement effect, and their absorption spectrum and first exciton peak, such as Figure 1 The size of the particles can be adjusted by adjusting the synthesis parameters during the synthesis process to achieve precise control of the absorption spectrum from visible light to infrared. The synthesis parameters can refer to temperature, raw material component ratio, etc. Colloidal quantum dots can be integrated and compatible with a variety of substrates through low-cost solution methods such as spin coating, blade coating, spray coating, roll-to-roll, etc.

[0030] Due to the confinement characteristics of colloidal quantum dots, the external quantum efficiency spectrum of a photodetector based on a single-sized colloidal quantum dot will have a wide trough region. In this trough region, the external quantum efficiency (EQE) is low, at around 20%, such as Figure 2 , in the wavelength range of 1200nm-1500nm, a wide "trough" of low external quantum efficiency will appear.

[0031] To this end, the inventors of the present application propose integrating colloidal quantum dots of various sizes into preset positions on the same silicon-based focal plane, and the positions at which colloidal quantum dots of various sizes are integrated on the silicon-based readout circuit can be distributed according to a preset array, forming a preset and fixed correspondence with the pixel distribution on the focal plane of the imaging sensor, and utilizing the high absorption characteristics of different first exciton peaks of colloidal quantum dots of different sizes to achieve a technical concept of full coverage of the visible light to short-wave infrared spectrum and high quantum efficiency.

[0032] Under the technical concept of integrating colloidal quantum dots of different sizes into a silicon-based readout circuit at a preset array position, the inventors of the present application further proposed a method for preparing a colloidal quantum dot functional layer containing colloidal quantum dots of multiple sizes, and using an optoelectronic device containing the colloidal quantum dot functional layer, a silicon-based focal plane imaging sensor that can achieve full coverage of the visible light to short-wave infrared spectrum and high quantum efficiency is obtained. The technical solution using this technical concept has at least the following advantages: 1) The raw materials of the colloidal quantum dots are synthesized in large quantities by solution processing, and the cost is very low compared to the high-temperature epitaxially grown indium gallium arsenide materials; 2) Compared to indium gallium arsenide materials, colloidal quantum dots can be prepared to absorb wide spectrum, so they can also absorb visible light, so the focal plane imaging sensor based on colloidal quantum dots can achieve full coverage of the visible light to short-wave infrared spectrum; 3) The flip-chip bonding process in the traditional indium gallium arsenide short-wave infrared focal plane sensor is eliminated, and the monolithic integration of colloidal quantum dots and silicon-based readout circuits is achieved. 4) The absorption coefficient of colloidal quantum dots is very high, and a film of about 0.4 microns can effectively absorb infrared light. Compared with the pixel size of 10 microns, the lateral crosstalk of colloidal quantum dot focal plane imaging sensors can be very low, so the step of photolithography patterning of the pixel area can be omitted, reducing costs.

[0033] Each colloidal quantum dot of the same size is arranged at a preset position on the silicon-based readout circuit. The size and position of the colloidal quantum dots can be precisely controlled. Therefore, according to different demand scenarios, multi-sized colloidal quantum dots with different absorption spectral ranges can be integrated into the same silicon-based focal plane readout circuit according to the preset array position. By utilizing the high absorption characteristics of different first exciton peaks of different colloidal quantum dots, full coverage of the visible light to short-wave infrared spectrum and high quantum efficiency can be achieved, such as Figure 3 , while the overall EQE value is improved, the EQE at the trough is also greatly improved.

[0034] See also Figure 4, a silicon-based focal plane imaging sensor provided in an embodiment of the present application, comprising: a silicon-based readout circuit 11 and an optoelectronic device 12 integrated on the silicon-based readout circuit 11. The optoelectronic device 12 comprises a top electrode 121 for receiving an optical signal, a bottom electrode 123 attached to the silicon-based readout circuit 11, and a colloidal quantum dot functional layer 122 located between the top electrode 121 and the bottom electrode 123. The colloidal quantum dot functional layer 122 comprises colloidal quantum dots of m sizes, the m sizes being between 4.5 nm and 8.2 nm, the first exciton absorption peaks of the m sizes of the colloidal quantum dots being in a range of between 1 μm and 3 μm, and each colloidal quantum dot of the same size is distributed in an array at a preset position on the silicon-based readout circuit 11.

[0035] Among them, the colloidal quantum dots of m sizes can be composed of colloidal quantum dots of the same material or different materials, such as m-sized lead sulfide colloidal quantum dots, or m-sized lead sulfide colloidal quantum dots, lead selenide colloidal quantum dots, mercury telluride colloidal quantum dots, indium arsenic colloidal quantum dots, indium antimony colloidal quantum dots and other colloidal quantum dots of different materials and sizes.

[0036] In the above embodiment, by integrating m kinds of colloidal quantum dots of different sizes into preset positions of the silicon-based readout circuit 11, and the positions where the colloidal quantum dots of each size are integrated on the silicon-based readout circuit 11 can be distributed according to a preset array, forming a preset and fixed correspondence with the distribution of pixels 31 on the focal plane 30 of the imaging sensor, thereby eliminating the flip-chip bonding process, making wafer-level mass production of silicon-based focal plane imaging sensors based on colloidal quantum dots possible, thereby reducing costs, improving the uniformity of light signals absorbed by colloidal quantum dots and facilitating improved imaging quality, and utilizing the high absorption characteristics of different first exciton peaks of different colloidal quantum dots to achieve full coverage of a wide spectrum from visible light to short-wave infrared and high quantum efficiency.

[0037] In an optional example, the first exciton absorption peak corresponding to the colloidal quantum dots that achieve full coverage of a wide spectrum from visible light to short-wave infrared and high quantum efficiency is between 1 μm and 3 μm, which can be achieved by integrating 9 colloidal quantum dots of different sizes on the same silicon-based focal plane readout circuit 11. The 9 quantum dots have different first exciton absorption peaks. According to the quantum confinement effect of the colloidal quantum dots, the larger the quantum dot size, the longer the wavelength corresponding to the first exciton absorption peak. The 9 colloidal quantum dots are all lead sulfide materials, and the corresponding nanoparticle diameters increase from 4.5 nm to 8.2 nm.

[0038] See also Figure 5In some embodiments, colloidal quantum dots of m sizes are respectively arranged corresponding to each pixel 31 to form a mixed-size quantum dot filter unit 21. The mixed-size quantum dot filter unit 21 is arranged one-to-one with the pixel 31 on the focal plane 30 of the imaging sensor. In each mixed-size quantum dot filter unit 21, colloidal quantum dots of m sizes are arranged according to predetermined positions, that is, the positions of colloidal quantum dots of the same size in each mixed-size quantum dot filter unit 21 are fixed. For the focal plane 30 of the entire imaging sensor, the arrangement array of colloidal quantum dots of the same size on the focal plane 30 is consistent with the arrangement array of the pixel 31 on the focal plane 30.

[0039] Optionally, the focal plane 30 of the imaging sensor has a*b pixels 31, each of which includes n*n sub-pixels 311, where m=n*n. That is, colloidal quantum dots of different sizes correspond to different sub-pixels 311 in each pixel 31. Among them, a*b pixels 31 can refer to 1280×1024, 1024×768, 1920×1280, etc., each pixel 31 contains sub-pixels 311 with an array of 3*3. For each pixel 31, the position of each sub-pixel 311 corresponds to a colloidal quantum dot of a size. In an optional specific example, in each of the mixed-size quantum dot filter units 21, colloidal quantum dots of the same size are arranged corresponding to the sub-pixels 311 at the same position in the corresponding pixel 31. The mixed-size quantum dot filter units 21 arranged one by one with the pixel 31 can uniformly absorb light signals of corresponding wavelengths to generate current signals, which is beneficial to improving imaging quality.

[0040] See also Figure 6 In some embodiments, the focal plane 30 of the imaging sensor is divided into m regions 32, and each region 32 corresponds to a single-size quantum dot filter unit 23. The m-size colloidal quantum dot sub-regions 32 are respectively integrated into the same silicon-based focal plane readout circuit, and each region 32 contains multiple pixels 31. Since the area of ​​the region 32 is relatively large, it can be Figure 5 For the illustrated embodiment, the preparation process of integrating colloidal quantum dots of different sizes onto the same silicon-based focal plane 30 can be relatively simplified.

[0041] The integration method of integrating the colloidal quantum dot functional layer containing colloidal quantum dots of various sizes into the silicon-based readout circuit 11 includes but is not limited to integrating it into a silicon-based integrated circuit using a photoconductor, a phototransistor and a photodiode. Figure 4Taking the photoelectric device 12 as a photodiode as an example, in the silicon-based focal plane imaging sensor, the photodiode including the colloidal quantum dot functional layer 122 also includes a carrier transport layer 125 located between the colloidal quantum dot functional layer 122 and the top electrode 121, and between the colloidal quantum dot functional layer 122 and the bottom electrode 123. The top electrode 121 is a transparent electrode, and the colloidal quantum dot functional layer 122 is a photosensitive layer. The photodiode is provided with a reverse bias by the bottom electrode 123 and the top electrode 121. The light signal is irradiated from the front, passes through the transparent top electrode 121, and is absorbed by the photosensitive layer formed by the colloidal quantum dots of multiple sizes. The generated current signal is read out through the bottom electrode 123 and the silicon-based readout circuit 11.

[0042] On the other hand, please refer to Figure 7 , a method for preparing a colloidal quantum dot functional layer is also provided, wherein the colloidal quantum dot functional layer 122 refers to the colloidal quantum dot functional layer 122 included in the optoelectronic device 12 in the silicon-based focal plane imaging sensor in the aforementioned embodiment, and the method comprises:

[0043] S101 , according to the distribution of pixels on the focal plane of the imaging sensor, colloidal electron dots of m sizes are preset to correspond to the m array areas respectively.

[0044] Among them, colloidal quantum dots of the same size are distributed in a preset array on the focal plane of the imaging sensor. By forming a preset array area corresponding to colloidal quantum dots of different sizes, the size and position of the colloidal quantum dots on the focal plane, as well as the corresponding relationship between colloidal quantum dots of different sizes and pixels on the focal plane, can be precisely controlled.

[0045] S103, selecting a first size as the target size of colloidal quantum dots, and integrating them into a corresponding array area on the focal plane through a single integration preparation step; wherein the single integration preparation step includes integrating the colloidal quantum dots of the target size on the focal plane according to the array area corresponding to the distribution of the colloidal quantum dots of the target size.

[0046] S105, select the next size as the target size of colloidal quantum dots, and integrate them into the corresponding array area on the focal plane through an integration preparation step again, and repeat this step until the colloidal quantum dots of the mth size are integrated into the corresponding array area on the focal plane.

[0047] The colloidal quantum dots of m sizes are sequentially integrated onto the focal plane through m integration preparation steps, and the integration preparation steps for integrating the colloidal quantum dots of each size onto the focal plane can be the same. For each integration preparation step, the colloidal quantum dots of the target size are the colloidal quantum dots of the corresponding size currently selected.

[0048] The target size of colloidal quantum dots corresponds to the distribution array area, such as Figure 5 As shown, taking the example of colloidal quantum dots of m sizes corresponding to each pixel 31 forming a mixed-size quantum dot filter unit 21, the array area 32 corresponding to the colloidal quantum dots of the first size refers to the array area 32 corresponding to the position of the first sub-pixel 311 in each pixel 31 on the focal plane 30; the array area 32 corresponding to the colloidal quantum dots of the second size refers to the array area 32 corresponding to the position of the second sub-pixel 311 in each pixel 31 on the focal plane 30; and so on, the array area 32 corresponding to the colloidal quantum dots of the mth size refers to the array area 32 corresponding to the position of the last sub-pixel 311 in each pixel 31 on the focal plane 30. Figure 6 As shown, taking the example of m-sized colloidal quantum dots corresponding to m areas 32 on the focal plane 30 respectively forming a single-sized quantum dot filter unit 23, the array area 32 corresponding to the colloidal quantum dots of the first size refers to the array area 32 corresponding to the first area 32 on the focal plane 30; the array area 32 corresponding to the colloidal quantum dots of the second size refers to the array area 32 corresponding to the second area 32 on the focal plane 30; and so on, the array area 32 corresponding to the colloidal quantum dots of the mth size refers to the array area 32 corresponding to the mth area 32 on the focal plane 30.

[0049] In the above embodiment, the colloidal quantum dot functional layer is prepared, and m kinds of colloidal quantum dots of different sizes are integrated into preset positions of the silicon-based readout circuit, so that the positions of colloidal quantum dots of various sizes integrated on the silicon-based readout circuit can be distributed according to a preset array, and the colloidal quantum dots of different sizes form a preset and fixed correspondence with the pixel distribution on the focal plane of the imaging sensor, eliminating the flip-chip bonding process, thereby reducing costs, and the optoelectronic device including the colloidal quantum dot functional layer is integrated into the silicon-based readout circuit. The colloidal quantum dot functional layer acts as a photosensitive layer to absorb light signals and generate current signals, which are then read out through the bottom electrode and the silicon-based readout circuit. The high absorption characteristics of different first exciton peaks of different colloidal quantum dots can achieve full coverage of a wide spectrum from visible light to short-wave infrared and high quantum efficiency.

[0050] In some embodiments, in step S103, the one-step integrated preparation step includes:

[0051] Integrating colloidal quantum dots of target size on a focal plane by a solution processing method; wherein the solution processing method comprises one of the following: spin coating, blade coating, spray coating, and roll-to-roll process;

[0052] According to the array area corresponding to the distribution of colloidal quantum dots of the target size, the redundant colloidal quantum dots on the focal plane are removed.

[0053] Taking the example of using colloidal quantum dots of various sizes to form a mixed-size quantum dot filter unit 21 corresponding to each pixel 31, the existing silicon-based focal plane readout circuit, after a series of post-processing steps (including but not limited to flattening, metal electrode enlargement, etc.), integrates colloidal quantum dots of different sizes with different absorption spectra into the silicon-based focal plane readout circuit through a solution processing method. The preparation process of this integration example can be summarized as follows: after the colloidal quantum dots of the first size are integrated into the circuit through a simple solution method, such as spin coating, scraping, spraying, and roll-to-roll, the excess colloidal quantum dots are removed by a removal process step; repeat this process until all the colloidal quantum dots of the n2th size are integrated into the silicon-based focal plane readout circuit.

[0054] Taking the example of dividing the silicon-based readout circuit 11 into regions 32, where one region 32 corresponds to a colloidal quantum dot of one size to form a single-size quantum dot filter unit 23, colloidal quantum dots of m sizes are divided into m regions 32 and integrated into the same silicon-based readout circuit 11 to achieve wide spectrum and high external quantum efficiency coverage from visible light to short-wave infrared (0.4-3μm). The area of ​​region 32 is relatively large, usually reaching the order of 10-100 microns. After integrating the colloidal quantum dots of the first size on the silicon-based readout circuit 11 using the solution processing method, the excess colloidal quantum dots are removed using the removal process step to form an m=1 region, and in each region 32, there is no need to perform complex patterning due to low lateral crosstalk. This step is repeated m times until all the colloidal quantum dots of m sizes with different absorption spectra are integrated into the silicon-based readout circuit 11.

[0055] Optionally, the process step of removing excess colloidal quantum dots on the focal plane includes one of the following:

[0056] After the current integrated preparation step is performed, the colloidal quantum dots in the array region corresponding to the colloidal quantum dots of the target size selected in the current integrated preparation step are cross-linked by a self-crosslinking process, and the excess colloidal quantum dots outside the array region are washed, dissolved and removed by a solvent;

[0057] The quantum dot film layer formed after the previous integration preparation step is covered with photoresist, and after the current integration preparation step is performed, the photoresist outside the corresponding array area in the current integration preparation step is removed through a photoresist stripping process.

[0058] Self-crosslinking can be achieved by utilizing the characteristics of quantum dots themselves, plus external stimulation, such as adding a mask to the film and then irradiating it with ultraviolet light. The quantum dots irradiated by the ultraviolet light will be cross-linked and will not be dissolved by the subsequent solvent. The uncross-linked quantum dots will be dissolved and washed away by the solvent, thus finally realizing the patterning of quantum dot film. During each integrated preparation step for quantum dots of different sizes, the quantum dots at the corresponding overlapping positions will not be washed and dissolved by the solvent because the quantum dots in the lower layer have been self-crosslinked, so the excess colloidal quantum dots can be accurately removed.

[0059] The photoresist lift-off process uses photoresist to isolate the colloidal quantum dot layer formed by the two previous and subsequent integrated preparation steps. By removing the photoresist layer in areas other than the current array area, the overlapping quantum dots on the photoresist can be removed at the same time, and the excess colloidal quantum dots can be accurately removed.

[0060] In some embodiments, in step S103, the one-step integrated preparation step includes:

[0061] According to the array area corresponding to the distribution of colloidal quantum dots of the target size, the colloidal quantum dots of the target size are printed to the designated position on the focal plane by using quantum dot ink printing.

[0062] In each integration preparation step, after a size of colloidal quantum dots is selected, the corresponding distribution position is determined on the focal plane of the imaging sensor, and then the quantum dots of the corresponding size are directly printed to the corresponding position through quantum dot ink printing. In this way, the size and position of the colloidal quantum dots can be precisely controlled, and multi-size colloidal quantum dots with different absorption spectral ranges can be conveniently integrated into the same silicon-based focal plane readout circuit according to preset array positions according to different demand scenarios.

[0063] On the other hand, the present application further provides a photoelectric device 12, comprising a colloidal quantum dot functional layer obtained by the preparation method of the colloidal quantum dot functional layer provided in any embodiment of the present application.

[0064] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A silicon-based focal plane imaging sensor, characterized in that: include: Silicon-based readout circuit; An optoelectronic device, integrated on the silicon-based readout circuit, the optoelectronic device comprising a top electrode for receiving an optical signal, a bottom electrode attached to the silicon-based readout circuit, and a colloidal quantum dot functional layer located between the top electrode and the bottom electrode; The colloidal quantum dot functional layer contains colloidal quantum dots of m sizes, wherein the m sizes are between 4.5 nm and 8.2 nm, and the first exciton absorption peak range of the m sizes of the colloidal quantum dots is between 1 μm and 3 μm. Each colloidal quantum dot of the same size is distributed in an array at a preset position on the silicon-based readout circuit.

2. The silicon-based focal plane imaging sensor according to claim 1, wherein: The colloidal quantum dots of m sizes are respectively arranged corresponding to each pixel to form a mixed-size quantum dot filter unit.

3. The silicon-based focal plane imaging sensor according to claim 2, wherein: The focal plane of the imaging sensor has a*b pixels, each of which contains sub-pixels in an array of n*n, where m=n*n.

4. The silicon-based focal plane imaging sensor according to claim 3, characterized in that: In each of the mixed-size quantum dot filter units, colloidal quantum dots of the same size are arranged correspondingly to sub-pixels at the same position in the corresponding pixel.

5. The silicon-based focal plane imaging sensor according to claim 1, wherein: The focal plane of the imaging sensor is divided into m regions, each of which corresponds to a single-size quantum dot filter unit of a size.

6. The silicon-based focal plane imaging sensor according to claim 1, wherein: A carrier transport layer is formed between the colloidal quantum dot functional layer and the top electrode, and between the colloidal quantum dot functional layer and the bottom electrode, respectively.

7. The silicon-based focal plane imaging sensor according to any one of claims 1 to 6, characterized in that: The m is 9; the colloidal quantum dot functional layer is a photosensitive layer, which absorbs the light signal transmitted through the top electrode and generates a current signal to be read out through the bottom electrode and the silicon-based readout circuit.

8. A method for preparing a colloidal quantum dot functional layer, wherein the colloidal quantum dot functional layer comprises colloidal quantum dots of m sizes, wherein the m sizes are between 4.5 nm and 8.2 nm, and the first exciton absorption peak of the m sizes of the colloidal quantum dots ranges from 1 μm to 3 μm, characterized in that: include: According to the distribution of pixels on the focal plane of the imaging sensor, colloidal electron dots of m sizes are preset to correspond to the m array areas respectively; Selecting colloidal quantum dots of a first size as a target size, and integrating them into a corresponding array area on a focal plane through a one-time integration preparation step; wherein the one-time integration preparation step includes integrating the colloidal quantum dots of the target size on the focal plane according to the array area corresponding to the distribution of the colloidal quantum dots of the target size; Select the next size of colloidal quantum dots as the target size, and integrate them into the corresponding array area on the focal plane through an integration preparation step again. Repeat this step until the colloidal quantum dots of the mth size are integrated into the corresponding array area on the focal plane.

9. The method for preparing a colloidal quantum dot functional layer according to claim 8, characterized in that: The method integrates the colloidal quantum dots of the target size on the focal plane according to the array area corresponding to the distribution of the colloidal quantum dots of the target size, including: Integrating colloidal quantum dots of target size on a focal plane by a solution processing method; wherein the solution processing method includes one of the following: spin coating, blade coating, spray coating, and roll-to-roll process; According to the array area corresponding to the distribution of colloidal quantum dots of the target size, the redundant colloidal quantum dots on the focal plane are removed.

10. The method for preparing a colloidal quantum dot functional layer according to claim 8, characterized in that: The removal process step of removing excess colloidal quantum dots on the focal plane includes one of the following: After the current integrated preparation step is performed, the colloidal quantum dots in the array region corresponding to the colloidal quantum dots of the target size selected in the current integrated preparation step are cross-linked by a self-crosslinking process, and the excess colloidal quantum dots outside the array region are washed, dissolved and removed by a solvent; The quantum dot film layer formed after the previous integration preparation step is covered with photoresist, and after the current integration preparation step is performed, the photoresist outside the corresponding array area in the current integration preparation step is removed through a photoresist stripping process.

11. The method for preparing a colloidal quantum dot functional layer according to claim 8, characterized in that: The method integrates the colloidal quantum dots of the target size on the focal plane according to the array area corresponding to the distribution of the colloidal quantum dots of the target size, including: According to the array area corresponding to the distribution of colloidal quantum dots of the target size, the colloidal quantum dots of the target size are printed to the designated position on the focal plane by using quantum dot ink printing.

12. A photoelectric device, characterized in that: A colloidal quantum dot functional layer comprising a colloidal quantum dot functional layer obtained by the preparation method of the colloidal quantum dot functional layer according to any one of claims 8 to 11.

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