A compact spectrometer based on an optical cascade architecture

Abstract

This application discloses a compact spectrometer based on an optical cascade architecture, comprising: a top electrochromic device serving as an in-situ light modulation layer for adjusting the transmittance or reflectivity of incident light through an electrochromic effect; and a bottom photodetector serving as a light detection layer for receiving the light signal modulated by the two stacked electrochromic devices and converting it into an electrical signal output; wherein the electrochromic device and the photodetector are vertically stacked together. Integrating the voltage-tunable spectral response electrochromic device with the photodetector optimizes spectral analysis performance. This not only improves spectral resolution and accuracy but also broadens the detection range, covering important wavelengths from visible to near-infrared light. Simultaneously, the spectrometer's size is significantly reduced, making it more suitable for on-chip integration and miniaturized applications.

Description

Technical Field

[0001] This application relates to the field of spectral analysis technology, and in particular to a compact spectrometer based on an optical cascade architecture. Background Technology

[0002] As a scientific instrument capable of revealing information about the wavelength and intensity of light, the spectrometer plays a vital role in modern information society. It has wide applications not only in industrial process control, environmental monitoring, and biomedical diagnostics, but also plays a key role in scientific research such as spectral imaging, materials analysis, and chemical analysis. With continuous technological advancements and expanding applications, the demand for spectrometers is increasing, particularly in areas such as smart consumer electronics, wearable devices, remote industrial control / automation, and defense applications.

[0003] Traditional benchtop spectrometers typically employ physical optical components such as gratings and interferometers to perform spectral analysis. However, these instruments are often bulky, heavy, and complex to operate due to their long optical paths, the presence of moving mechanical parts, and complex external calibration elements (such as cosine correctors and integrating spheres), and they are also sensitive to environmental conditions. These inherent limitations make it difficult for traditional benchtop spectrometers to be widely adopted in the field of on-chip optoelectronics, especially in applications requiring miniaturization, lightweight design, portability, and high flexibility.

[0004] To overcome the limitations of traditional benchtop spectrometers, a new computational spectrometer technology has emerged in recent years. These computational spectrometers, based on the principles of wavelength multiplexing and matrix computation algorithms, achieve miniaturization, weight reduction, and portability through optimized optical design and electronic signal processing techniques. Computational spectrometers use wavelength multiplexing to collect light signals of different wavelengths through a single detector or detector array, and then use matrix computation algorithms to process the collected data to reconstruct the original spectral information. This method not only reduces the size and weight of the spectrometer but also improves spectral resolution and measurement accuracy.

[0005] Despite the numerous advantages of computational spectrometers, they also face several challenges and limitations. First, most computational spectrometers are manufactured using inorganic nanomaterials. While these materials possess excellent physical and chemical properties, they are typically rigid, making them difficult to adapt to the needs of flexible electronics such as wearable and portable devices. Second, most computational spectrometers have not yet solved the problem of measuring absolute spectral irradiance, limiting their use in applications requiring high-precision spectral radiation measurements. Furthermore, the design and manufacturing processes of computational spectrometers are relatively complex, requiring high-precision photolithography and sophisticated electronic signal processing techniques, which further increases their manufacturing costs and difficulty. Summary of the Invention

[0006] This application provides a compact spectrometer based on an optical cascade architecture, which enables the measurement of absolute spectral irradiance under various conditions.

[0007] To achieve the above objectives, the technical solution of this invention is as follows:

[0008] In a first aspect, embodiments of the present invention provide a compact spectrometer based on an optical cascade architecture, comprising: an electrochromic device at the top, serving as an in-situ light modulation layer of the spectrometer, for adjusting the transmittance or reflectivity of incident light through the electrochromic effect; and a photodetector at the bottom, serving as a light detection layer of the spectrometer, for receiving the light signal modulated by the two stacked electrochromic devices and converting it into an electrical signal for output; wherein the electrochromic device and the photodetector are stacked vertically together.

[0009] In some possible implementations, the number of electrochromic devices is at least one or more, and each electrochromic device includes a top ITO layer, an electrochromic polymer layer, an ion transport layer, an ion storage layer and a bottom ITO layer from top to bottom, forming a semi-transparent light modulation device that can independently and precisely adjust the transmittance or reflectivity of incident light.

[0010] In some possible implementations, the electrochromic device has different electrochromic properties, which are used to adjust the spectrum in different wavelength ranges; wherein the electrochromic properties include at least ECP-Purple and ECP-Blue.

[0011] In some possible implementations, the spectrometer also includes:

[0012] An electrical connection system includes at least one double-sided conductive metal strip for connecting the electrodes of the electrochromic device to the ITO layers on both sides for applying voltage to the electrochromic device; and a metal wire for connecting the photodetector, the metal wire being soldered to the photodetector with conductive silver adhesive for transmitting electrical signals; and an integrated module housing for vertically stacking and fixing the electrochromic device and the photodetector in the order of electrochromic device ECP-Purple, ECP-Blue and the photodetector to construct an optical cascade structure.

[0013] In some possible implementations, the photosensitive layer of the photodetector is made of a pre-designed semiconductor material to achieve efficient photoelectric conversion and a wide spectral response.

[0014] In some possible implementations, electrochromic devices and photodetectors use flexible substrate materials and flexible electrode materials to achieve the flexibility of the spectrometer, enabling it to maintain stable performance under bending or deformation conditions.

[0015] In some possible implementations, based on specific spectral range requirements, electrochromic devices and photodetectors can be replaced with materials that have high sensitivity to specific spectral ranges.

[0016] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0017] This invention presents a compact spectrometer based on an optical cascade architecture, which optimizes spectral analysis performance by integrating a voltage-tunable spectral response electrochromic device with a photodetector. This design not only improves spectral resolution and accuracy but also broadens the detection range, covering important wavelengths from visible to near-infrared light. Simultaneously, the spectrometer's size is significantly reduced, making it more suitable for on-chip integration and miniaturization applications. Furthermore, the spectrometer can measure absolute spectral irradiance, which is crucial for spectral analysis under various conditions. Its inherent high flexibility, coupled with the advanced engineering of organic electronic materials in terms of bandgap tunability, enables the spectrometer to adapt to the needs of different application scenarios, especially in the upcoming data / AI-driven era or various complex environments. Attached Figure Description

[0018] To more clearly illustrate the embodiments of the present invention, the accompanying drawings used in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram illustrating the working principle of an incident spectrum tuned spectrometer in the prior art.

[0020] Figure 2 This is a schematic diagram illustrating the working principle of a device response-tuned spectrometer based on existing technology.

[0021] Figure 3 A schematic diagram of a compact spectrometer based on an optical cascade architecture provided for the implementation of this invention;

[0022] Figure 4 This is a schematic diagram illustrating the working principle of a compact spectrometer based on an optical cascade architecture in an embodiment of the present invention.

[0023] Figure 5 This is a schematic diagram illustrating the relationship between wavelength and absolute light intensity in unknown light reconstructed through absolute radiation measurement in an embodiment of the present invention.

[0024] Figure 6 This is a schematic diagram illustrating the working principle of the spectrometer provided in an embodiment of the present invention;

[0025] Figure 7 This is a schematic diagram of the spectral responsivity of the spectrometer when different voltages are applied to the electrochromic device in an embodiment of the present invention;

[0026] Figure 8a This is a contour plot of the 3D matrix of the spectrometer responsivity in an embodiment of the present invention;

[0027] Figure 8b A schematic diagram showing the comparison between the monochromatic light reconstructed by the spectrometer and that of a commercial spectrometer;

[0028] Figure 8c This is a schematic diagram showing the performance indicators of the spectrometer in terms of Δλ, resolution, and PSNR.

[0029] Figure 8d A schematic diagram showing the structure in which the resolution of a spectrometer is determined by the wavelength difference between the two closest peaks;

[0030] Figure 8e Schematic diagrams showing the results of reconstructing quasi-monochromatic light using a spectrometer and a commercial spectrometer, respectively;

[0031] Figure 8f The diagram shows the results of narrowband light reconstruction by a spectrometer and a commercial spectrometer, respectively.

[0032] Figure 8g The diagrams show the results of broadband spectra reconstructed by a spectrometer and a commercial spectrometer, respectively.

[0033] Figure 8h This is a schematic diagram showing the LDR of a photodetector and the corresponding functional relationship between its responsivity and optical power.

[0034] Figure 8i A schematic diagram of the spectrum with absolute irradiance reconstructed from an organic spectrometer and a commercial spectrometer;

[0035] Figure 9a A schematic diagram of a flexible spectrometer for wearable devices;

[0036] Figure 9b The spectral responsivity matrix of the flexible spectrometer depends on the contour plot applied to the flexible electrochromic device fabricated on an ITO / PET substrate;

[0037] Figure 9c Spectral diagrams of quasi-monochromatic light, narrowband light, and broadband light reconstructed by a spectrometer and a commercial spectrometer;

[0038] Figure 9d This is a structural diagram illustrating the bandwidth, accuracy, M-value, footprint, and flexible availability of the spectrometer and other representative related works.

[0039] Figure 10aA schematic diagram of the spectral imaging process using a spectrometer and spatial scanning methods;

[0040] Figure 10b Spectral images of the reconstructed portrait of Confucius at different wavelengths;

[0041] Figure 10c A spectral image of Confucius reconstructed using a spectrometer;

[0042] Figure 10d A schematic diagram comparing the spectrum reconstructed by the spectrometer with the spectrum of a commercial spectrometer at points A and B marked in the illustration. Detailed Implementation

[0043] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0044] In the relevant descriptions of this embodiment, the terms "including," "containing," and "possessing" are all open terms and are generally understood to include but not limited to; the term "at least one" is generally understood to mean one or more, wherein "multiple" refers to two or more; the term "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single items or multiple items.

[0045] Those skilled in the art should understand that, in the following description of the embodiments of this application, the sequence of numbers does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0046] Those skilled in the art will understand that the numerical ranges in the embodiments of this application should be understood to specifically disclose each intermediate value between the upper and lower limits of the range. Any stated value or intermediate value within a stated range, as well as any other stated value or each smaller range between intermediate values ​​within a range, are also included within this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0047] To illustrate the technical solution of the present invention, specific embodiments are described below.

[0048] As a scientific instrument capable of revealing information about the wavelength and intensity of light, the spectrometer plays a vital role in modern information society. It has wide applications not only in industrial process control, environmental monitoring, and biomedical diagnostics, but also plays a key role in scientific research such as spectral imaging, materials analysis, and chemical analysis. With continuous technological advancements and expanding applications, the demand for spectrometers is increasing, particularly in areas such as smart consumer electronics, wearable devices, remote industrial control / automation, and defense applications.

[0049] To overcome the limitations of traditional benchtop spectrometers, a new computational spectrometer technology has emerged in recent years. These computational spectrometers, based on the principles of wavelength multiplexing and matrix computation algorithms, achieve miniaturization, weight reduction, and portability through optimized optical design and electronic signal processing techniques. Computational spectrometers use wavelength multiplexing to collect light signals of different wavelengths through a single detector or detector array, and then use matrix computation algorithms to process the collected data to reconstruct the original spectral information. This method not only reduces the size and weight of the spectrometer but also improves spectral resolution and measurement accuracy.

[0050] Pioneer computational spectrometers currently rely on dynamic wavelength multiplexing methods and operate in three steps: 1) learning to encode a working calibration matrix using a series of known monochromatic lights; 2) sampling the unknown spectrum by adjusting the incident light or photodetector to generate a dynamic light response matrix; and 3) reconstructing the unknown spectrum by combining and solving the two previous matrices using computational algorithms. The main difference between computational spectrometers to date lies primarily in adjusting the incident light or detector response. Therefore, these spectrometers can be categorized into two types. For example... Figure 1 and Figure 2 As shown. Regardless of the modulation used (incident spectrum or detector response), the generated calibration matrix should not have a linear dependence between any two sets, and it is always better to have as much dissimilarity as possible.

[0051] See Figure 1 As shown, Figure 1 This is a schematic diagram illustrating the working principle of an incident spectrum tuned spectrometer in the prior art. For the incident spectrum tuning category, this can be achieved by using a set of equivalent miniaturized optical elements (used as filters or dispersors) (such as...). Figure 1 As shown in i, the calibration matrix is ​​obtained to realize, for example, photonic chips, waveguides, multifocal superlenses, pinholes, filter arrays, microcones, multiple quantum wells, structured colored nanowires, etc., which are usually associated with specialized micro / nanoscale fabrication. In this category, the method can use a single equivalent but tunable optical element, through a combination of metasurface arrays and tunable liquid crystals to achieve the desired optical tuning (e.g., Figure 1(as shown in ii). However, in almost all of these processes, different optical array structures are required for spectral tuning, which makes manufacturing difficult and limits the footprint.

[0052] On the other hand, see Figure 2 As shown, Figure 2 This is a schematic diagram illustrating the working principle of a device-response tuned spectrometer using existing technology. Firstly, an equivalent array (see...) can be used... Figure 2 This can be achieved using methods such as gradient single nanowire alloys and perovskite arrays (as shown in i). The dynamic and wavelength-multiplexed spectral responses of this type of spectrometer are spatially distributed according to the components of the detector array, and this approach typically requires dedicated fabrication. Clearly, a better approach is to obtain the dynamic and wavelength-multiplexed spectral responses using only a single detector (see [i]). Figure 2 (as shown in ii).

[0053] Currently, the response of a single detector has become the mainstream in this category. Figure 2 (ii). This includes many tunable diodes based on van der Waals junctions, such as WSe2 / MoS2, ReSe2 / SnS2, and MoS2 / black phosphorus (BP). The spectral response varies from the above cases to the spatial distribution of multiple devices simultaneously (ii). Figure 2 The time deviation distribution of (i) transforms into a single degenerate device ( Figure 2 (ii). Despite significant achievements in minimizing footprint, bandgap engineering of two-dimensional material heterostructures with bias modulation characteristics requires a very wide and independent response to each modulation of the detector, thus sacrificing the flexibility of the optoelectronic performance required for the tuning device.

[0054] In some embodiments, a single-pixel spectrometer that eliminates the need for physically splitting light is the optimal choice if a wavelength-multiplexed dynamic optical response matrix can be achieved by adjusting only a single detector in a certain way, avoiding the need for any arrays, filters, interferometers, or moving / mechanical parts. Furthermore, ease of fabrication without dedicated nano / microscale processes, the mechanical flexibility of the device, and the ability to meet diverse application scenarios are crucial.

[0055] Based on this, embodiments of the present invention provide a compact spectrometer based on an optical cascade architecture, which solves the problem of measuring absolute spectral irradiance under various conditions.

[0056] Figure 3 A schematic diagram of a compact spectrometer based on an optical cascade architecture is provided for implementation of this invention. See [link to diagram]. Figure 3 As shown, the above-mentioned compact spectrometer may include:

[0057] The electrochromic device at the top serves as the in-situ light modulation layer of the spectrometer, used to adjust the transmittance or reflectivity of incident light through the electrochromic effect.

[0058] The photodetector at the bottom, serving as the light detection layer of the spectrometer, receives the light signal regulated by the two stacked electrochromic devices and converts it into an electrical signal output.

[0059] The electrochromic device and the photodetector are stacked vertically together.

[0060] It should be noted that optoelectronic materials have been driving significant technological innovations in the optoelectronic field, such as photodetectors, electrochromic devices, photovoltaics (OPV), and light-emitting diodes (OLEDs). Among these, photodetectors possess unique advantages in light sensing and detection. Besides their wide spectral range (300-1100 nm), they also exhibit inherent flexibility, making them promising candidates for next-generation spectrometers. They also demonstrate range-linear response (e.g., greater than 100 dB) in terms of light intensity, solution handling capabilities, and comparable or better detection performance.

[0061] In this embodiment of the invention, the compact spectrometer based on the optical cascade architecture consists of a single device composed of two integrated cascaded layers, without any complex array structure. The top-layer electrochromic device subunit serves as the field spectrum tuning unit, while the bottom-layer photodetector subunit simultaneously measures the tuning spectrum from the electrochromic device in the field.

[0062] Figure 4 This is a schematic diagram illustrating the working principle of a compact spectrometer based on an optical cascade architecture according to an embodiment of the present invention. See also... Figure 4 As shown, the spectrometer features an integrated two-layer single-detector device with in-situ dynamic optical tuning and a highly replaceable / optically tunable device for the required performance / scene. The reconstructed spectrum is obtained by solving the following formula (1).

[0063]

[0064] Where r(λ) represents the responsivity of the photodetector, and T(V) represents the transmittance of the electrochromic device.

[0065] In this embodiment of the invention, no spatial optical elements or detector array structures are required, and all devices are folded into a single pixel. By measuring the photocurrent of a spectrometer illuminated by an unknown spectrum in the wavelength multiplexing principle, and then calculating a cross-reference with self-calibration and a previously constructed responsivity matrix, any incoming unknown light / spectrum can be reconstructed, including monochromatic, narrowband, broadband light, etc., with precise absolute irradiance.

[0066] For example Figure 5As shown, Figure 5 This is a schematic diagram illustrating the relationship between wavelength and absolute spectral intensity in unknown light reconstructed through absolute radiometric measurements in an embodiment of the present invention. Figure 5 These include monochromatic, narrowband, broadband, and reconstruction spectra, respectively.

[0067] In some embodiments, the material used to manufacture the electrochromic device described above can be an organic material or an inorganic material.

[0068] Electrochromic devices made of organic materials can be called organic electrochromic devices (OECDs). They typically possess good flexibility, allowing them to be fabricated into thin films or coatings, and are easily processed through methods such as solution treatment, spraying, and printing. Furthermore, organic materials are generally inexpensive and can be mass-produced. For example, polythiophene and polypyrrole are widely used in electrochromic devices due to their high color change sensitivity and good cycle stability.

[0069] Electrochromic devices made of inorganic materials typically possess high thermal and chemical stability, and many inorganic materials, such as metal oxides, exhibit good electrical conductivity. However, compared to organic materials, inorganic materials are generally more expensive and require complex fabrication processes. For example, inorganic electrochromic materials can include transition metal oxides such as WO3 and NiO, which can change color through ion insertion / extraction processes and have been used in the OECD, typically exhibiting high optical modulation range and stability.

[0070] In some embodiments, the number of electrochromic devices is at least one or more.

[0071] As is understandable, electrochromic devices are materials or structures that undergo reversible color changes under the influence of an applied electric field through the injection / extraction of electrons or ions. To achieve specific color change effects or control the color of multiple regions, multiple electrochromic devices can work together. Alternatively, in some critical applications, to ensure system reliability and stability, multiple electrochromic devices can be used in a redundant design to prevent system collapse due to the failure of a single device.

[0072] Each electrochromic device comprises, from top to bottom, a top ITO layer, an electrochromic polymer layer, an ion transport layer, an ion storage layer, and a bottom ITO layer, forming a semi-transparent light modulation device capable of independently and precisely adjusting the transmittance or reflectivity of incident light.

[0073] The top indium tin oxide (ITO) layer serves as the top transparent electrode, allowing light to penetrate into the device while providing a connection point to external circuitry. The ITO layer, with its high transparency and excellent conductivity, is an indispensable component of OECDs.

[0074] The electrochromic polymer layer is a core component of the OECD, used to induce color changes under an electric field. This layer can be an organic material, such as the aforementioned polythiophene and polypyrrole, which achieve reversible color changes through redox reactions. It can also be an inorganic material, such as the aforementioned transition metal oxides (e.g., WO3, NiO), which can change color through ion insertion / extraction processes.

[0075] Ion transport layers are used to provide ion transport channels during electrochromic processes. They can be liquid, such as ionic liquids or electrolyte solutions, which possess high ionic conductivity and enable rapid ion transport. They can also be in gel or all-solid state; different states of ion transport layer materials offer varying degrees of stability and lifespan, allowing selection based on the specific requirements of the application.

[0076] Ion storage layers are used to balance charge changes during electrochromic processes, ensuring stable device operation. Ion storage layers are typically composed of high-capacity ion-conducting materials, such as PEDOT:PSS (poly(3,4-ethylenedioxythiophene):polystyrene sulfonate) or other polymer electrolytes.

[0077] Similar to the top ITO layer, the bottom ITO layer acts as a transparent electrode, providing connection to external circuitry. Together with the top ITO layer, it forms the electrode system of the OECD, driving the electrochromic process by applying an electric field.

[0078] In some embodiments, each electrochromic device in the electrochromic device may have different electrochromic characteristics, which are used to adjust the spectrum in different wavelength ranges respectively;

[0079] For example, electrochromic properties may include at least ECP-Purple and ECP-Blue.

[0080] In this embodiment of the invention, the electrochromic materials (ECP-Purple and ECP-Blue) enable more dynamic and precise wavelength-multiplexed light modulation. ECP-Purple and ECP-Blue exhibit excellent tunable spectra and high stability over a wide spectral range of 300-2000 nm. Specifically, due to the combined effect of bleaching and coloring states over a wide spectral range under electrochemical doping, the electrochromic polymers exhibit different transmittances.

[0081] In some embodiments, taking the OECD as an example, the manufacturing process of the above-mentioned electrochromic device may include:

[0082] A five-layer sandwich structure OECD with an ITO / electrochromic polymer / ionic liquid / PEDOT:PSS / ITO structure was constructed. A glass / ITO substrate (40×26×0.8mm) was used. 3 Thin-film resistivity: 8-12 ohm / sq) was pre-cleaned sequentially in an ultrasonic bath of detergent, deionized water, acetone, and isopropanol, followed by gas drying with nitrogen. Electrochromic polymers ECP-Blue and ECP-Purple were dissolved in chlorobenzene at concentrations of 15 and 20 mg / mL, respectively. The polymer solutions were then spin-coated onto a pre-cleaned ITO substrate at 2000 rpm for 45 s to form a thin film as the active layer. PEDOT:PSS was filtered through a 0.45 mm pore size filter and then spin-coated onto another ITO-coated glass substrate (40 × 26 × 0.8 mm) at 1800 rpm. 3 A thin-film resistivity (8-12 ohms / sq) was applied for 30 seconds as a charge storage layer. It was then annealed on a hot plate at 135°C for 25 minutes without any further processing. A substrate containing the active layer and charge storage layer was symmetrically assembled using double-sided adhesive tape (3M) as a spacer material. A solution containing the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([EMIM+][TFSI3], 1.0 mol·L⁻¹) was applied. 3 A propylene carbonate solution electrolyte is injected into the hollow core structure of the encapsulation as the electrolyte layer. All equipment is manufactured and assembled in a nitrogen-filled glove box.

[0083] In some embodiments, the photosensitive layer of the photodetector is made of a pre-selected semiconductor material to achieve efficient photoelectric conversion and a wide spectral response.

[0084] Among them, a photodetector is a device used to convert light signals into electrical signals. It includes various types of detectors, such as diodes, transistors, and photoconductive detectors.

[0085] Photodiodes, with their advantages of fast response, high sensitivity, and low noise, are widely used in optical communication, optical detection, and photoelectric measurement. Phototransistors, similar to ordinary transistors, have strong amplification capabilities and are used in photoelectric detection systems requiring signal amplification. Photoconductive detectors include various semiconductor photoconductors, i.e., photoresistors. In the absence of light, the photoresistance is high, and the current in the circuit is low; when exposed to light, the resistance decreases sharply, and the current in the circuit increases rapidly. They are widely used in fiber optic communication systems, fiber optic testing systems, fiber optic sensors, optical isolators, fiber optic transmission for color TVs, television image transmission, photodetectors for fast light sources, detection of weak light signals, receiving devices in laser rangefinders, photoelectric measurement and photoelectric transformers in high-voltage circuits, computer data transmission, photoelectric automatic control, and optical measurement.

[0086] In some embodiments, the aforementioned preset semiconductor material can be either an organic semiconductor or an inorganic semiconductor. Organic photodetectors (OPDs) primarily use organic semiconductor materials as the photosensitive layer, achieving photoelectric conversion through the generation and transport of photogenerated carriers. These detectors can be further classified into organic semiconductor photodetectors and organic-inorganic hybrid photodetectors based on material type. Organic semiconductor materials possess advantages such as flexibility, solubility, and low cost, and can be prepared using solution methods or vacuum evaporation methods. Organic photodetectors show promising application prospects in areas such as environmental pollution detection, biological imaging processes, health monitoring, and security monitoring across two different wavelengths.

[0087] Inorganic photodetectors primarily use inorganic semiconductor materials, such as silicon (Si), germanium (Ge), and lead selenide (PbSe), as the photosensitive layer. Based on their working principle, inorganic photodetectors can be broadly classified into photon detectors and thermal detectors. Inorganic semiconductor materials typically possess high photoelectric conversion efficiency and stability, and have wide applications in various fields of military and national economy, such as missile guidance, infrared thermal imaging, and infrared remote sensing.

[0088] Taking an organic photodetector as an example, the OPD can be fabricated based on the high-performance non-fullerene acceptor PCE-10 and the organic optoelectronic non-fullerene acceptor material COTIC-4F in the active layer. The donor PCE-10 and the narrow-bandgap non-fullerene acceptor COTIC-4F are chosen for their excellent performance in low dark current (Idark = 5.6 pA, Irms = 4.1 pA, V = 0 V), wide spectral response range (300-1100 nm), high responsivity (R = 0.45 AW⁻¹, 970 nm), and fast response (433 ns). Note that state-of-the-art OPDs typically exhibit broad linear responses. For example, the PCE-10:COTIC-4F-based OPD used in this embodiment can have a light intensity range of nearly eight orders of magnitude, 152 dB, which is crucial for accurate measurement of absolute irradiance. Furthermore, its operational advantage of achieving optimal performance under zero-voltage conditions is significant, contributing to a reduction in the overall power consumption of the spectrometer.

[0089] Specifically, using PCE-10 and COTIC-4F as OPD materials, extensive visible to near-infrared (Vis-NIR) light measurements were performed. The aforementioned spectrometer achieved a resolution of 0.56 nm, a peak monochromatic wavelength accuracy of 0.14 nm, a measurable spectral mismatch as low as 0.030, and an absolute spectral irradiance of 10. -8 Up to 10 -4 Wcm -2 nm -1 The spectral range is 400 to 1000 nanometers.

[0090] In some embodiments, taking OPD as an example, the fabrication of the above-mentioned photodetector may include:

[0091] The organic photodetector based on the active layer PCE-10:COTIC-4F was fabricated using a glass / ITO / ZnO / active layer / MoOx / Ag structure. First, the glass / ITO substrate was pre-cleaned sequentially in an ultrasonic bath of detergent, deionized water, acetone, and isopropanol, followed by nitrogen drying. Then, the ITO substrate was irradiated with UV light for 15 minutes in a UV ozone chamber (Jelight). A layer of ZnO (approximately 30 nm) was deposited by spin-coating a ZnO precursor onto the pre-cleaned ITO substrate, annealed in air at 200°C for 1 hour, and then transferred to an argon-filled glove box. PCE-10:COTIC-4F (1:1.5 w / w, 15 mg / mL) was then applied. -1A mixed solution of chlorobenzene and 0.5% chloronaphthalene was spin-coated at 2000 rpm for 40 seconds. The resulting film was then annealed at 110 °C and heated on a hot plate for 10 minutes. Subsequently, MoOx was deposited on top of the active layer to obtain a hole transport layer with a thickness of 15 nm. Finally, a 2 × 10⁻⁶ m² / m²· ... –6 An Ag electrode with a thickness of 100 nm was fabricated under Pa using thermal evaporation. The specific active area of ​​the final device was determined using a pre-designed mask and microscopy.

[0092] In this embodiment of the invention, the high performance of OECD (for optical modulation) and OPD (for optical detection) is integrated to realize a single-detector spectrometer with high resolution, accuracy, and measurable absolute irradiance over a wide spectral range. Furthermore, combining the advantages of the solution's process technology with the inherent flexibility of organic electronics, it features an adjustable device footprint (from 2 × 2 μm). 2 Up to 4×4mm 2 A flexible single-detector spectrometer was developed and achieved performance similar to that of a rigid substrate.

[0093] For example, taking the electrochromic device as an OECD and the photodetector as an OPD, the fabrication process of the above spectrometer may include:

[0094] The integration of the spectrometer involves the assembly of near-infrared OPD and OECD components. Initially, the OECD electrodes are interconnected with the ITO layers on both sides via double-sided conductive metal strips (1×5 mm in width and length) to facilitate the application of voltage to the OECD. Then, metal wires with a diameter of 100 micrometers are soldered to the OPD electrodes using conductive silver adhesive. The metal strips and wires can be made of any metal, such as copper, aluminum, or gold, and can be determined based on specific requirements. These components are integrated using a spectrometer module housing (e.g., length, width, thickness: 45×30×6 mm). The components are vertically stacked and secured in the order of the electrochromic devices ECP-Purple, ECP-Blue, and the near-infrared OPD, thus establishing an optical cascade structure.

[0095] In some embodiments, based on specific spectral range requirements, electrochromic devices and photodetectors can be replaced with materials that have high sensitivity to specific spectral ranges.

[0096] Understandably, the availability of highly replaceable electrochromic devices and photodetector materials makes spectrometers highly adaptable to different requirements or specific needs, such as certain spectral detection ranges, detection limits, and even operating temperatures and humidity. For example, when measuring a specific spectrum in a narrow band (e.g., the visible and ultraviolet range), materials with high sensitivity to that spectral range can be selected to improve spectrometer performance.

[0097] The working principle of the compact spectrometer based on optical cascade architecture provided by the present invention will be explained below through specific embodiments.

[0098] Understandably, in the aforementioned spectrometer, the modulation of the incident light is achieved through two sequentially independent electrochromic devices: an OECD based on ECP-violet and ECP-blue. Under the control of the bias applied by the OECD, the number of neutral and polarized states undergoes corresponding reversible changes, with transmittance varying within the range of 300-1000 nm. The visible spectral region is allocated to neutral state absorption (π-π* transitions) covering 400-600 / 700 nm, while polarized states (P1-P2) contribute above the isoabsorption point (ECP-violet, 620 nm; ECP-Blue, 703 nm). Figure 6 As shown, Figure 6 This is a schematic diagram illustrating the working principle of the spectrometer based on OECD and OPD in an embodiment of the present invention. Figure 6 In the diagram, i represents the mechanism of the spectrometer, ii represents the schematic diagram of the neutral and polaron states of the electrochromic polymer, and iii represents the schematic diagram of the energy levels of the bulk heterojunctions of PCE-10 and COTIC-4F.

[0099] Therefore, the dynamic wavelength multiplexing modulation reaching the OPD sub-cell is achieved by adjusting the neutral and polarization states in the OECD, which change in opposite directions, resulting in a dynamic wavelength multiplexing response from the OPD cell used for incident spectrum measurements. In other words, the synchronous dynamic wavelength multiplexing tuning of the incident spectrum of the OPD cell and the dynamic optical response of the OPD cell to this tuned spectrum generate a responsivity matrix R(λ,Vp,Vb) based on the violet and ECP-blue OECD (e.g., ). Figure 7 The diagram shows the spectral responsivity of the spectrometer when different voltages are applied to the OECD. This serves as the basis for constructing a mathematically solvable matrix with a system of linear equations for reconstructing a spectrometer using a single detector. The cascading order of the two OECDs does not affect the spectrometer's responsivity.

[0100] According to the workflow diagram, the above-mentioned spectrometer consists of three steps: a learning step (acquiring the response matrix), a sampling step (measuring the photocurrent of the unknown spectrum), and a reconstruction step.

[0101] The first step involves obtaining the learned responsivity matrix pb as a function of the wavelengths of a series of monochromatic lights and the voltages applied by the two OECDs. A complete three-dimensional (3D) matrix is ​​generated by completing all l×m×n steps of the learning process (l, m, n representing the shifts of λ, Vp, and Vb, corresponding to the wavelengths and voltages of the two OECDs). For example, to demonstrate a complete 400–1000 nm incident light measurement, a 600×11×16 (105,600 data sets) learning matrix can be generated. In the spectral responsivity matrix R(λ,Vp,Vb), all previously reported studies show a lateral variation of the continuously tunable bandgap along the wavelength dimension. In contrast, the spectral response matrix shows a vertical variation of the responsivity across the entire spectral range, indicating a new approach to developing reconstructive spectrometer instruments. Furthermore, due to the high responsivity of the OPD across the entire spectral range, the spectrometer maintains a responsivity exceeding 0.15 AW even after modulation by two OECDs. -1 Peak response.

[0102] In the second sampling step, when 11 × 16 different displacement voltages are applied to the OCED unit, the photocurrent of the spectrometer under unknown incident light is measured according to the wavelength multiplexing principle, generating a two-dimensional photocurrent matrix I(Vp, Vb). This can be automatically completed by scanning with an I / V meter. Finally, the spectrum of the incident light can be reconstructed based on the pb generated by the responsivity matrix through the above learning process and the photocurrent matrix pb measured in the sampling step. Clearly, the solvability and performance of the spectrometer are limited by the differences in spectral transmittance between any set of OECDs with different wavelength-multiplexed tuned light and the diversity of OPD responses. That is, any set of responses under different modulations needs to be highly dissimilar (nonlinear). Intuitively, the greater the difference in response, the higher the accuracy and resolution. Furthermore, from a simple mathematical perspective, this difference is not linear between any set of responses.

[0103] Specifically, for the reconstruction step, through normal theoretical derivation, the integral equation can be expressed by the following formula (2):

[0104]

[0105] Where r(λ) and T(λ,Vp,Vb) are the responsivity of the OPD and the combined spectral transmittance of the two OECDs. Together with r(λ) and T(λ,Vp,Vb), the spectral matrix of the integrated spectrometer responsivity matrix is ​​generated: R(λ,Vp,Vb), which can be obtained in advance in the first step. P(λ) represents λ. i To λ j (λ i <λ jThe unknown spectral intensity is determined within a certain range. The integration of these two-layer OPD and OECD devices generates a dynamically wavelength-multiplexed photocurrent matrix I(Vp,Vb) of the modulated spectrum via two OECDs. The unknown spectrum can then be reconstructed by calculating the constrained least-squares solution using the well-known Tikhonov regularization. Measurement errors have been addressed using conventional methods of solving the equations. Here, the regularization parameters are obtained via the generalized cross-validation (GCV) method. Importantly, by calculating cross-references with self-calibration and the previously constructed matrix, reconstructed spectra with absolute irradiance can also be obtained across any wavelength range or the entire spectrum due to the large LDR of the OPD as described above.

[0106] In this embodiment of the invention, when PCE-10 and COTIC-4F are used as photoactive materials in OPD, the spectrometer modulated by two OECDs under variables p and b exhibits tunable responsivity in the spectral range of 400-1000 nm. Figure 8a The 3D spectrometer responsivity matrix contour plot shown in this embodiment of the invention depends on p and b applied to the OECD (this matrix includes 176 different spectral responses with 11(p) × 16(b) voltage values ​​and a wavelength step of 1 nm). In this embodiment, the device's performance under monochromatic light (FWHM ≈ 2 nm) was first evaluated and reconstructed. Figure 8b Taking monochromatic light in the 730-750nm range as an example, the spectrometer has an average accuracy Δλ of 0.14nm (Δλ: the peak difference between the reconstructed spectrum and the reference spectrum), a wavelength resolution as high as 6900 nm, and a peak signal-to-noise ratio (PSNR) exceeding 30dB. Figure 8c As shown in the figure, it exhibits a high degree of consistency with the reference spectrum obtained using a commercial spectrometer. Furthermore, the spectral resolution (defined as the ability to distinguish the most recent pair of spectral peaks) can be as low as 0.56 nm. Figure 8d Utilizing the high response of the aforementioned spectrometer across the entire 400-1000 nm spectrum, it can be used to reconstruct various quasi-monochromatic (FWHM≈8 nm) and narrowband (FWHM≈30 nm) ranges throughout the spectrum. For example... Figure 8e As shown in Figure 8f, the spectrum reconstructed by the spectrometer is highly consistent with the reference spectrum obtained by the commercial spectrometer in both shape and central peak position.

[0107] Furthermore, to comprehensively evaluate the reliability and performance of the spectrometer's functions, rather than using one of many single performance parameters, this embodiment of the invention introduces a spectral mismatch factor (M-value) as an overall quality factor to quantify the differences between the reconstructed spectra, comparing the initial spectrum with the reference spectrum. Note that a smaller mismatch M-value between the reconstructed spectra compared to the reference spectrum indicates better spectral reconstruction reliability and accuracy of the spectrometer. Through this comprehensive performance evaluation of the M-parameter, we found that our spectrometer generally outperforms state-of-the-art results in the literature and is also comparable to the performance of large commercial spectrometers. For example, the average M-values ​​for the quasi-monochromatic and narrowband spectra reconstructed by the spectrometer are 0.023 and 0.029, respectively, which are superior to values ​​in the prior art and very close to those of widely used commercial spectrometers (e.g., model: Ocean USB 4000). Moreover, the spectrometer can measure natural or complex spectra with the same reliability. For example, the M-values ​​for reconstructed spectra of indoor LED lights and the 400 to 1000 nm infrared broadband range are as low as 0.024 and 0.039, respectively. Figure 8g It is superior to existing reconstructed spectrometers.

[0108] In some embodiments, using the strategies provided in this invention and the same device architecture, devices with customized performance parameters, such as specified spectral detection range, resolution, accuracy, or even environmental requirements or OECD level, can be directly and easily fabricated simply by changing the active organic material in the OPD. Spectrometers were fabricated using different active materials in the OPD (e.g., PM6:F-2F and PM6:CH17) for detecting wavelengths of 400-750 nm and 400-850 nm, respectively. Compared to a spectrometer using PM6:CH17 (Δ22 nm), the spectrometer fabricated using PM6:F-2F in the OPD exhibited higher accuracy (Δ14 nm).

[0109] In some embodiments, for absolute spectral irradiance, measuring the power of electromagnetic radiation received per unit area within a unit wavelength interval is one of the most important parameters in spectroscopic analysis. As mentioned above, the spectrometer described above has a large linear dynamic range (LDR) of 152 dB, ensuring a robust response over a wide spectral range, such as... Figure 8h As shown. This function enables the spectrometer to accurately reconstruct narrowband spectra (peak wavelength = 725 nm) with an intensity range of 0.96 to 42.6 μW / cm². -2 nm -1 ( Figure 8i Compared to existing commercial spectrometers (model: Ocean USB 4000), the minimum peak intensity change is 5.1%. Furthermore, quasi-monochromatic light and narrowband light of different wavelengths (10...) -8 Up to 10 -4 W·cm -2·nm -1 The absolute light intensity of the sample was also successfully reconstructed, showing a minimum peak intensity variation of 1.2% compared to the reference spectrum obtained by a commercial spectrometer. All these results demonstrate that the compact spectrometer of this invention can achieve superior functionality and performance compared to existing compact spectrometers. The single-detector spectrometer of this invention exhibits significant advantages over commercial spectrometers because it uses a self-calibrated and in-situ calibrated responsivity matrix for measurement and has no movable or spatially dependent mechanical / optical components that typically require calibration over time.

[0110] In some embodiments, the electrochromic device and photodetector use flexible substrate materials and flexible electrode materials to achieve the flexibility of the spectrometer, enabling it to maintain stable performance under bending or deformation conditions.

[0111] Understandably, firstly, flexible substrate materials are key to achieving device flexibility. These materials include, but are not limited to, quartz, glass, polyethylene terephthalate (PET), and polyimide (PI). Among them, polymeric materials such as PET and PI, in particular, possess excellent flexibility and mechanical strength, maintaining performance stability under bending or deformation conditions. Secondly, the selection of flexible electrode materials can improve the performance stability of the device. Examples include transparent conductive oxides (TCOs) such as ITO, ultrathin silver nanowires, and PSS:PEDOT. These materials not only possess excellent conductivity and transparency but also good flexibility and mechanical stability, maintaining electrode integrity and performance stability under bending or deformation conditions. This not only improves the performance stability of electrochromic devices and photodetectors but also broadens their application areas.

[0112] In practical applications, combining flexible substrate materials and flexible electrode materials can produce flexible electrochromic devices and photodetectors with excellent performance. For example, these flexible substrate materials enable electrochromic devices and photodetectors to be applied in emerging technology fields such as wearable devices, flexible displays, and smart windows.

[0113] It should be noted that flexible spectrometers offer a bendable configuration, resulting in significant advancements in adaptability, portability, and integration with wearable electronics (such as...). Figure 9a (As shown). The solution-handle nature of spectrometers offers inherent advantages for the fabrication of flexible spectrometers. Embodiments of this invention enable the fabrication of the first flexible spectrometer on an ITO / PET substrate, combining the inherent flexibility and high performance of spectrometers (method). Similar to rigid spectrometers, flexible spectrometers also exhibit nearly identical capabilities, enabling precise measurements across the entire spectral range of 400-1000 nm (e.g., Figure 9b(As shown). Following the same unknown spectrum reconstruction workflow, the flexible spectrometer exhibits near-rigid performance in terms of spectral accuracy (0.57 nm) and resolution (2.58 nm). Furthermore, the flexible spectrometer successfully reconstructed quasi-monochromatic, narrowband, and broadband spectra (e.g., ...). Figure 9c As shown), the minimum M value is 0.031, very close to that of the rigid spectrometer (0.024). To demonstrate the potential of the spectrometers in meeting the flexibility requirements of wearable systems, embodiments of the present invention evaluated their spectral reconstruction capabilities under bending conditions. Compared to the reference spectrum, the curvature is 2.7m. -1 The M-value of the reconstructed spectrum under bending conditions is 0.035 (0.031 for rigid spectra), highlighting its ability to maintain spectral measurement fidelity under severe deformation. Furthermore, after multiple bending and releasing cycles, e.g., 300 times, the change in the M-value (0.037) of the flexible spectrometer is negligible. Figure 9d The bandwidth, accuracy, M-value, space footprint, and flexibility of the spectrometers in this invention embodiment are summarized and compared with those of other relevant representative works. This shows that the single-detector flexible spectrometer, based on an optical cascade architecture, exhibits comprehensive advantages compared with existing computational spectrometers.

[0114] Taking OPD and OECD as examples, to manufacture OPD and OECD devices, PEI / ITO substrates are initially cut into 1×1 and 40×26 mm sizes. Subsequently, a mixture of PDMS precursor and crosslinking agent is spin-coated at a 10:1 ratio onto a pre-cleaned glass substrate of the same size as the prepared PET / ITO substrate at 5000 rpm for 30 seconds to form a polydimethylsiloxane (PDMS) film. The uncured PDMS is then baked at 80°C for 10 minutes to form the final film. Next, a flexible PET / ITO substrate is adhered to the glass / PDMS to provide mechanical support. The manufacturing process of flexible OECD devices follows that of rigid devices. ECP-Blue and ECP-Purple at concentrations of 15 and 20 mg / mL, respectively, were spin-coated onto a Glass / PDMS / PET / ITO substrate at 2000 rpm for 45 s to form an active layer (the PET / ITO substrate, containing a color-changing active layer and an ion storage layer, can be peeled off from the glass / PDMS and cut to the desired smaller size). These layers were assembled with a PET / ITO layer coated with PEDOT:PSS to form a sandwich structure, where the latter acts as the ion storage layer. Finally, ions injected liquid [EMIM+][TFSI+] from the PC into the sandwich structure of the OECD, which served as a charge transport medium to obtain a flexible OECD (flex-OECD).

[0115] To prepare a flexible OPD, a standard structure can be used: ITO / PEDOT:PSS / PCE-10:COTI C-4F / PDINO / Ag. First, PEDOT:PSS is diluted with deionized water at a 1:1 ratio and spin-coated onto Glass / PDMS / PET / ITO. It is then annealed at 120°C for 20 minutes to form a hole transport layer, which is then formed on the substrate. The substrate is then transferred to a nitrogen-filled glove box. The active layer, PCE-10:COTIC-4F (1:1.5 w / w, 15 mg mL⁻¹, chlorobenzene containing 0.5% chloronaphthalene), is spin-coated at 2000 rpm for 35 seconds and annealed at 110°C for 10 minutes. Subsequently, a methanol solution containing 1.5 mg mL⁻¹ PDINO is spin-coated at 3000 rpm for 15 seconds to form an electron transport layer. Afterward, silver electrodes of different sizes (100 nm) are thermally evaporated onto the electron transport layer to obtain a flexible OPD, which is then peeled off from the glass substrate. The micron-sized OPD is achieved by etching silver electrodes using a photolithography process. Finally, as a sequence of electrochromic devices ECP-Purple, ECP-Blue, and OPD, the components are vertically stacked and fixed to fabricate an optically cascaded organic spectrometer.

[0116] Understandably, spectral imaging is a powerful technique that combines spectral and imaging capabilities. It can gather detailed information about the composition and characteristics of objects and surfaces in ways impossible with traditional imaging systems. Spatial scanning demonstrates the application of spectrometers in spectral imaging (e.g., Figure 10a (As shown). Using the target image as... Figure 10a Taking the image of Confucius shown as an example, Confucius's portrait was projected onto a spectrometer and then scanned in 2-millimeter steps. By varying the Vbias of the OECD, photocurrent was measured in each mapping step, generating a three-dimensional photocurrent data cube (XY). Subsequently, a reconstruction algorithm was used to calculate and convert the photocurrent data cube into a spectral cube Current Matrix (XY). A cross-sectional view of this cube on a plane produces a series of single-wavelength spatial maps (such as...). Figure 10b (As shown). By applying existing International Commission on Illumination (CIE) standardized color matching functions to the spectral data cube, it is possible to generate pseudo-color images that are very similar to the original photograph (e.g., Figure 10c (As shown). Figure 10c Reconstructed spectra of different points on a portrait versus reference spectra obtained using existing commercial spectrometers (e.g.) Figure 10d The results (shown) demonstrate a high degree of consistency, further proving the spectrometer's spectral imaging potential.

[0117] In this embodiment of the invention, a flexible and compact spectrometer was designed and manufactured by integrating a single-pixel OECD and OPD with an optical cascade architecture. In addition to high performance comparable to commercially available bulk products, it features a resolution of 0.56 nm, an accuracy of 0.14 nm, a wide detection range of 400 to 1000 nm, a footprint as small as a few micrometers, and remarkable stability. Under various conditions, the spectrometer successfully achieved 10 -8 Up to 10 -4 Wcm -2 nm -1 The measurement of absolute spectral irradiance under various light intensities, crucial for state-of-the-art computational spectrometers, addresses a key challenge currently faced. Furthermore, the flexible spectrometer in this embodiment exhibits performance and high mechanical stability comparable to rigid spectrometers, offering unprecedented advantages for wearable and implantable devices. Based on the high performance of the flexible spectrometer, spectral imaging can be successfully achieved by resolving its spectral information through spatial scanning images. Therefore, the optical cascade architecture provides a versatile design opportunity for high-performance, compact spectrometers, holding immense potential for the commercialization of flexible, miniaturized hyperspectral cameras.

[0118] The working principle of the spectrometer provided in this embodiment of the invention will be explained below with reference to a specific example:

[0119] In this embodiment of the invention, device characterization and measurement can be performed using a semiconductor parameter analyzer and a source meter to test the current density-voltage in darkness and the current-time (IT) curves under 950 nm illumination, a pulse frequency of 0.5 Hz, and zero bias. The responsivity-wavelength correlation is measured on a QE-R. The UV-Vis transmittance of the device is measured using a UVVis spectrometer.

[0120] The responsivity matrix of the spectrometer can be obtained using a QE-R and a monochromator (e.g., an Agilent Cary 3000). First, the intensity of a xenon lamp source is calibrated using silicon (Si) in the range of 300–1100 nm with wavelength steps of 0.5, 1, 5, and 10 nm. This monochromatic light is then used to measure the response of the OPD. The response under different biases can be measured by varying the bias provided by an arbitrary wavefunction generator (Rigol DG992) applied to the OECD. For a two-layer OECD device, the voltage on the ECP-Purple is first fixed, then the voltage on the ECP-Blue is adjusted, and the OPD responsivity is measured using multiple different biases (-2, -1, -0.8, -0.7). One cycle consists of 0.6, -0.5, -0.4, -0.3, -0.2, -0.1, 0, 0.1, 0.2, 0.4, 0.6, and 0.8 V. After one cycle, the ECP-Blue returns to the initial bias, and then the voltage on the ECP-Purple changes to the next value while measuring the response under the next ECP-Blue bias cycle, until all 11 biases (0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1V) have been traversed on the ECP-Purple.

[0121] After obtaining the spectrometer's responsivity matrix, the next step involves measuring the spectrometer's photocurrent to reconstruct the unknown spectrum. In this embodiment, five different types of light sources can be selected for spectral reconstruction: extremely monochromatic light (FWHM≈2nm, Agilent Cary 3000), quasi-monochromatic light (FWHM≈4nm, QE-R), narrowband light (FWHM≈30nm, LED Hasunopto), and broadband light (indoor LED and NIR broadband). The intensity of the light source can be controlled using an adjustable neutral density filter. Both the spectrometer and commercial spectrometers are fixed on a movable slide. The bias applied to the OECD is provided by an arbitrary wavefunction generator (Rigol DG992). The spectrometer's photocurrent is collected using a digital source meter (Keithley 2400). The order in which voltages are applied to the OECD during photocurrent measurement is the same as the order during photocurrent measurement.

[0122] Among them, for the responsivity matrix, first fix the voltage on the ECP-Purple device, and then adjust and cyclically apply the voltage on the ECP-Blue. After completing one cycle, the voltage applied on the ECP-Blue returns to the initial value, and then the voltage applied on the ECP-Purple changes to the next value. To reduce the time and errors associated with manual data processing, embodiments of the present invention can also provide a programming method to process data. During data collection, the duration of each applied bias voltage is kept constant. Considering the overall time of data acquisition and signal stability, the duration of each bias is set to 5 seconds. Measure the linear dynamic range (LDR) at 1000 nm under different light intensities and calibrate using a low dark current photodiode (such as Hamamatsu S1133-01). Collect the photocurrent and noise current of the device through a semiconductor parameter analyzer (such as B1500A, Keysight).

[0123] The spectrum can be reconstructed by integrating the algorithm with the responsivity matrix after collecting the current. The relationship description between the photocurrent and the light intensity can be expressed by the following formula (3):

[0124]

[0125] Among them, P(λ) represents the intensity of the unknown spectrum in the wavelength range from i to j (i < j). R(λ, Vp, Vb) represents the spectral responsivity function of the wavelength, where p and b are the biases on the ECP-Purple device and the ECP-Blue device, and I(Vp, Vb) represents the measured photocurrent.

[0126] After discretizing the above formula (3), it can be expressed by the following formula (4):

[0127]

[0128] After further simplification, it is expressed by the following formula (5):

[0129] P·R = I (5)

[0130] The spectral reconstruction of the above formula (5) becomes the solution of the equation. However, the measurement errors of the responsivity and photocurrent caused by inevitable noise and manufacturing differences make this linear system an ill-posed problem. It is difficult to solve these equations using ordinary non-stationary iterative methods. Therefore, embodiments of the present invention can adopt a regularization method to solve. The main purpose of regularization is to stabilize the solution of the problem by incorporating additional information about the expected solution, so as to obtain a stable and accurate solution. Tikhonov regularization has become an effective method for solving such ill-posed equations. It can be expressed by the following formula (6):

[0131]

[0132] in This represents the residual term, characterizing the uncertainty of the reconstruction; Let represent the penalty term, approximating the noise intensity in the reconstruction; δ is the regularization parameter that balances the weights between the residual and penalty terms. By solving the minimization problem shown in equation (6), a high-precision, interference-resistant spectrum can be reconstructed. The choice of δ should consider both the magnitude of the residual and the magnitude of the penalty term, seeking a balance between the two. The GCV (Generalized Cross-Validation) method ensures that both components are minimized.

[0133] In some embodiments, the stability of the above-mentioned spectrometer can also be tested.

[0134] Specifically, the stability of the aforementioned spectrometers encompasses the stability of both the OECD and OPD, and also determines the overall stability of the spectrometer. The transmittance of the ECP-Purple and the ECP-Blue electrochromic device were tested under different bias voltages to evaluate the cyclic and sustained stability of the OECD. The sustained stability of the OPD was evaluated using LED illumination (980nm) with a 0.5Hz square wave modulation frequency driven by a signal generator. A primary concern with integrated spectrometers is the stability of the OECD in long-term bias applications. The stability of the spectrometer was assessed by measuring the light response of the OPD while applying a long-term bias to the OECD. The storage stability of the organic-based spectrometer was evaluated by measuring the light response of the OPD after storing the spectrometer in air for one week. Furthermore, the recovery of photocurrent during current collection can also serve as an indicator of spectrometer stability. The flexible spectrometer was tested under bending conditions using a self-made apparatus.

[0135] This invention presents a compact spectrometer based on an optical cascade architecture, which optimizes spectral analysis performance by integrating a voltage-tunable spectral response OECD with an OPD. This design not only improves spectral resolution and accuracy but also broadens the detection range, covering important bands from visible to near-infrared light. Simultaneously, the spectrometer's size is significantly reduced, making it more suitable for on-chip integration and miniaturized applications. Furthermore, the spectrometer can measure absolute spectral irradiance, which is crucial for spectral analysis under various conditions. Its inherent high flexibility, coupled with the advanced engineering of organic electronic materials in terms of bandgap tunability, enables the spectrometer to adapt to the needs of different application scenarios, especially in the upcoming data / AI-driven era or various complex environments.

[0136] The various embodiments in this specification are described in a progressive manner. For the same or similar parts between the various embodiments, please refer to each other. Each embodiment focuses on describing the differences from other embodiments.

[0137] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit this application. Although this application 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 or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.

Claims

1. A compact spectrometer based on an optical cascade architecture, characterized in that, include The electrochromic device at the top serves as the in-situ light modulation layer of the spectrometer, used to adjust the transmittance or reflectivity of incident light through the electrochromic effect. The photodetector located at the bottom serves as the light detection layer of the spectrometer, used to receive the light signal regulated by the two stacked electrochromic devices and convert it into an electrical signal output. The two electrochromic devices and the photodetector are stacked vertically together. The spectrometer contains two electrochromic devices. Each electrochromic device consists of a top ITO layer, an electrochromic polymer layer, an ion transport layer, an ion storage layer, and a bottom ITO layer, forming a semi-transparent light modulation device that can independently and precisely adjust the transmittance or reflectivity of incident light. Each electrochromic device has different electrochromic properties, which are used to adjust the spectrum in different wavelength ranges; wherein, the electrochromic properties are ECP-Purple and ECP-Blue, respectively. The spectrometer further includes: an electrical connection system comprising at least one double-sided conductive metal strip for connecting the electrodes of the two electrochromic devices to the ITO layers on both sides, for applying voltage to the two electrochromic devices; a metal wire for connecting the photodetector, the metal wire being soldered to the photodetector with conductive silver adhesive for transmitting electrical signals; and an integrated module housing for vertically stacking and fixing the two electrochromic devices and the photodetector in the order of electrochromic device ECP-Purple, electrochromic device ECP-Blue, and photodetector, to construct an optical cascade structure. Each electrochromic device and the photodetector uses flexible substrate and flexible electrode materials to achieve the flexibility of the spectrometer, enabling it to maintain stable performance under bending or deformation conditions.

2. The spectrometer according to claim 1, characterized in that, The photosensitive layer of the photodetector is made of a pre-selected semiconductor material to achieve efficient photoelectric conversion and a wide spectral response.

3. The spectrometer according to claim 2, characterized in that, Based on specific spectral range requirements, each electrochromic device and the photodetector can be replaced with a material that has high sensitivity to the specific spectral range.

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