A new method for in-situ analysis of electrode interface effect based on surface-enhanced raman effect

Abstract

This invention discloses a novel method for in-situ analysis of electrode interface effects based on surface-enhanced Raman (SERS). The method includes: vertically incident a laser beam onto the surface of a bottom-gate top-contact OFET (Optical Field-Electronic Field-Sensitive Device) device, focusing on the interface region between the silver source / drain electrode and the organic semiconductor layer, as well as the channel center; performing in-situ multispectral imaging tests at the metal-semiconductor interface and the channel center; and analyzing charge transfer, carrier accumulation, and interface state effects at the electrode-organic semiconductor interface. This invention utilizes the silver source / drain electrode of the OFET itself as the SERS active substrate to construct a charge transfer resonance-dominated enhancement system, eliminating the need for additional fabrication of any noble metal nanostructures or SERS substrates and preventing damage to the original device structure. Furthermore, this invention enables real-time monitoring of interface Raman signal changes under different bias conditions by applying different gate and source / drain bias voltages during device operation, thereby dynamically analyzing the carrier accumulation and charge transfer processes at the interface.

Description

Technical Field

[0001] This invention belongs to the technical field of interface characterization of organic electronic devices, and specifically relates to a new method for in-situ analysis of electrode interface effects based on surface-enhanced Raman effect. Background Technology

[0002] Organic field-effect transistors (OFETs), as core devices in organic electronics, have shown great application potential in fields such as flexible displays, wearable sensors, and electronic skin. In organic field-effect transistors, the interface effects between the electrodes and the organic semiconductor play a crucial role in device performance, including contact resistance, charge injection efficiency, interface state trapping, and carrier accumulation. These interface processes directly determine core performance parameters such as device mobility, on / off ratio, and response speed. Therefore, developing analytical methods that can accurately and in-situ characterize electrode-organic interface effects is of significant guiding importance for optimizing device interfaces and improving device performance.

[0003] Currently, traditional interface characterization methods mainly include X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and transmission electron microscopy (TEM). However, most of these methods are offline characterization techniques, requiring destructive treatment of the device. They cannot perform in-situ dynamic monitoring while the device is in operation, nor can they reflect changes in interface carriers under electrical bias in real time. Furthermore, these methods have limited spatial resolution, making it difficult to accurately locate the nanoscale interface region at the electrode edge, and they cannot achieve simultaneous electrical control and optical characterization.

[0004] Raman scattering spectroscopy, as a molecular fingerprinting technique, can provide vibrational and rotational information of molecules, thereby reflecting changes in molecular structure, electronic states, and interactions. It is a powerful tool for studying organic semiconductor interfaces. Due to its non-destructive nature, relaxed requirements for testing environments, sensitivity to molecular polarization and electron-phonon coupling, and ability to provide fingerprint-like structural information, Raman spectroscopy has demonstrated strong in-situ analytical potential in fields such as biology and carbon materials. However, the signal intensity of ordinary Raman scattering is very weak. For weak signals at electrode interfaces, especially spectral changes induced by a small number of charge carriers at the interface, the sensitivity of ordinary Raman spectroscopy is far from sufficient to achieve effective detection.

[0005] Surface-enhanced Raman scattering (SERS) technology can leverage the local electromagnetic field enhancement effect of noble metal nanostructures to amplify Raman signals by several orders of magnitude, thereby achieving ultra-high sensitivity detection. However, traditional SERS characterization methods require the additional fabrication of SERS substrates consisting of noble metal nanoparticles, nanowires, or nanostructures. This not only damages the original device structure and introduces additional impurities but also alters the interfacial properties of the device itself, failing to accurately reflect interfacial effects under device operating conditions. Furthermore, most existing SERS characterization techniques are static, unable to dynamically monitor interfacial changes during device operation while applying an electrical bias voltage, making in-situ dynamic analysis of electrode interfacial effects difficult.

[0006] Therefore, developing a SERS analysis method that can dynamically analyze electrode interface effects in situ without additional modification is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] The main objective of this invention is to address the shortcomings of existing organic field-effect transistor (OFET) electrode interface characterization techniques, such as the need for additional SERS active substrate preparation, easy damage to the original device structure, inability to achieve in-situ dynamic monitoring under device operating conditions, and insufficient sensitivity for weak interface signal detection. This invention provides a new method for in-situ analysis of electrode interface effects based on surface-enhanced Raman effect, which can achieve high-sensitivity, non-destructive, and dynamic characterization of the electrode-semiconductor interface without additional device modification.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] One aspect of the present invention provides a novel method for in-situ analysis of electrode interface effects based on surface-enhanced Raman effect, comprising the following steps:

[0010] The laser beam from the Raman microscope is incident vertically onto the surface of the bottom-gate top-contact organic field-effect transistor device and focused on the interface region between the source / drain electrodes and the organic semiconductor layer, as well as the center of the channel.

[0011] In-situ multispectral imaging tests were performed at the metal-semiconductor interface and the center of the channel: gate voltage and source-drain bias voltage were applied, and while the carrier transport state was controlled, the interface Raman spectra and the Raman spectra at the center of the channel were collected in situ under different bias conditions.

[0012] Based on the changes in peak intensity of in-situ Raman spectra under different bias conditions, the charge transfer, carrier accumulation and interface state effects at the electrode-organic semiconductor interface are analyzed.

[0013] As a preferred technical solution, the bottom-gate top-contact organic field-effect transistor device includes, from bottom to top, a gate, an organic insulating layer, an active layer, and source / drain electrodes.

[0014] As a preferred technical solution, the gate is made of silicon wafer; the insulating layer is made of polymethyl methacrylate; the active layer is made of a mixture of donor and acceptor materials in a mass ratio of 1:1; and the source and drain electrodes are made of silver.

[0015] As a preferred technical solution, the laser beam wavelength of the Raman microscope is 532 nm, 633 nm or 785 nm.

[0016] As a preferred technical solution, the range of the applied gate voltage is 0 V to -30 V, and the range of the source-drain bias voltage is 0 V to -30 V.

[0017] As a preferred technical solution, the bottom-gate top-contact organic field-effect transistor device is prepared by the following steps:

[0018] Clean the substrate;

[0019] An insulating layer is prepared on a cleaned substrate by self-assembly or spin coating.

[0020] An active layer was prepared on the insulating layer by spin coating.

[0021] Metal source and drain electrodes were fabricated on the active layer using a vacuum thermal evaporation method.

[0022] As a preferred technical solution, the following steps are also included:

[0023] Before in-situ multispectral imaging testing, in-situ Raman imaging was used to determine the non-uniform region, and the laser power and exposure time were set, using a platform-moving scanning method.

[0024] Another aspect of the present invention provides a novel system for in-situ analysis of electrode interface effects based on surface-enhanced Raman effect, comprising a bottom-gate top-contact organic field-effect transistor device and an in-situ testing system.

[0025] The bottom-gate top-contact organic field-effect transistor device includes, from bottom to top, a gate, an organic insulating layer, an active layer, and source / drain electrodes;

[0026] The in-situ testing system includes a confocal micro Raman spectrometer for acquiring Raman spectra of bottom-gate-top-contact organic field-effect transistor devices and an electrical signal detection device for analyzing Raman spectra.

[0027] As a preferred technical solution, the confocal micro Raman spectrometer includes a laser, a beam expander, a filter, a microscope, a slit, a grating, and a detector;

[0028] The laser emitted by the laser is focused onto the bottom-gate top-contact organic field-effect transistor device by passing through a beam expander, a filter, and a microscope in sequence, generating Raman scattered light; the Raman scattered light is received by the detector by passing through a filter, a slit, and a grating in sequence.

[0029] The detector converts optical signals into electrical signals and transmits them to the electrical signal detection device.

[0030] As a preferred technical solution, the electrical signal detection device includes a probe station for placing the bottom-gate top-contact organic field-effect transistor device, a semiconductor parameter analyzer, and a computer. The computer is connected to the semiconductor parameter analyzer and a confocal micro Raman spectrometer, respectively, and the semiconductor parameter analyzer is connected to the probe station.

[0031] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0032] (1) This invention directly utilizes the silver source and drain electrodes of the organic field-effect transistor itself as the active substrate of SERS to construct an enhancement system dominated by charge transfer resonance. No additional noble metal nanostructures or SERS substrates are required. This will not damage the original structure of the device or introduce any additional impurities, thus achieving true non-destructive in-situ characterization.

[0033] (2) This invention relies on the charge transfer resonance between the silver electrode and the organic semiconductor as the core SERS enhancement mechanism. The signal enhancement has high interface selectivity and only targets the electrode-organic semiconductor interface to amplify the signal. It can accurately capture the weak charge transfer, storage and carrier-induced spectral changes at the interface. It has high detection sensitivity and strong targeting, and solves the problems of insufficient sensitivity of ordinary Raman spectroscopy and poor interface selectivity of traditional electromagnetic field enhanced SERS.

[0034] (3) This invention realizes dynamic in-situ characterization, which can apply different gate voltages and source / drain biases under the working state of the device, control the interface charge transfer intensity and carrier accumulation in-situ, and monitor the changes of interface Raman signal under different bias conditions in real time, thereby dynamically analyzing the carrier accumulation and charge transfer process of the interface, which is impossible to achieve by traditional offline characterization methods.

[0035] (4) This invention realizes the synchronous acquisition of electrical and optical signals, and can directly link the macroscopic electrical performance of the device with the microscopic interface charge transfer and molecular-level changes. It provides direct experimental basis for a deeper understanding of the physical mechanism of electrode interface effect and has important guiding significance for the interface optimization and performance improvement of the device.

[0036] (5) The method of the present invention is fully compatible with existing organic field-effect transistor fabrication processes, does not require any special modification of the device, is simple to operate, low in cost, and can be widely used for interface characterization of various organic electronic devices. It is especially suitable for in-situ analysis of charge transfer behavior at the electrode-semiconductor interface and has broad application prospects. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the structure of a bottom-gate top-contact organic field-effect transistor device according to an embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of the structure of polymethyl methacrylate (PMMA) and non-fullerene material (ITIC) according to an embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram of the optical path of a confocal micro Raman spectrometer according to an embodiment of the present invention;

[0040] Figure 4 These are Raman spectra of the silicon / silicon dioxide / organic insulating layer / P3HT:ITIC (mass ratio 1:1) / Ag electrode device structure of this invention under different wavelength laser scanning at different positions;

[0041] Figure 5 This is an image of the characteristic peak intensity of the silicon / silicon dioxide / organic insulating layer / P3HT:ITIC (mass ratio 1:1) / Ag electrode device structure of the present invention under different wavelength laser scanning at different positions;

[0042] Figure 6 These are Raman images of the silicon / silicon dioxide / organic insulating layer / P3HT:ITIC (mass ratio 1:1) / Ag electrode device structure of this invention under different gate voltages when the source-drain voltage is 0V;

[0043] Figure 7 Raman images of the silicon / silicon dioxide / organic insulating layer / P3HT:ITIC (mass ratio 1:1) / Ag electrode device structure of this invention at different gate voltages when the source-drain voltage is -30V. Detailed Implementation

[0044] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative effort are within the scope of protection of the present application.

[0045] Example 1:

[0046] This embodiment provides a novel method for in-situ analysis of electrode interface effects based on surface-enhanced Raman effect, including the following steps:

[0047] S1. The laser beam of the Raman microscope is incident vertically onto the surface of the bottom gate top contact type organic field-effect transistor device and focused on the interface region between the source / drain electrode and the organic semiconductor layer and the center of the channel.

[0048] S2. In-situ multispectral imaging tests are performed at the metal-semiconductor interface and the center of the channel, specifically:

[0049] By applying gate voltage and source / drain bias, the Raman spectra of the interface and the Raman spectra at the center of the channel under different bias conditions are collected in situ while the carrier transport state is controlled.

[0050] S3. Based on the changes in peak intensity of in-situ Raman spectra under different bias conditions, analyze the charge transfer, carrier accumulation and interface state effects at the electrode-organic semiconductor interface.

[0051] Example 2:

[0052] This embodiment provides a novel system for in-situ analysis of electrode interface effects based on surface-enhanced Raman effect, including a bottom-gate top-contact organic field-effect transistor device and an in-situ testing system;

[0053] The bottom-gate top-contact organic field-effect transistor device includes, from bottom to top, a gate, an organic insulating layer, an active layer, and source / drain electrodes;

[0054] The in-situ testing system includes a confocal micro Raman spectrometer for acquiring Raman spectra of bottom-gate-top-contact organic field-effect transistor devices and an electrical signal detection device for analyzing Raman spectra.

[0055] It should be noted that the system provided in Embodiment 2 is only an example of the above-described division of functional modules. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure can be divided into different functional modules to complete all or part of the functions described above. This system can be applied to a new method for in-situ analysis of electrode interface effects based on surface-enhanced Raman effect in the above embodiment.

[0056] Example 3:

[0057] To enable those skilled in the art to better implement the technical solutions of the present invention, this embodiment further illustrates a new method and system for in-situ analysis of electrode interface effects based on surface-enhanced Raman effect in Embodiments 1 and 2 by setting detailed parameters and configurations.

[0058] (1) such as Figure 1 As shown, the bottom-gate top-contact organic field-effect transistor device (hereinafter referred to as the device sample) used in this embodiment includes, from bottom to top, a silicon substrate, an insulating layer (organic insulating layer), an active layer (organic semiconductor layer), and source / drain electrodes.

[0059] The silicon substrate is a silicon wafer, or a layer of silicon dioxide (preferably 300 nm thick) on a layer of polycrystalline silicon wafer (preferably 0.5 mm thick).

[0060] The organic insulating layer material is polymethyl methacrylate (PMMA).

[0061] like Figure 2 As shown, the organic semiconductor layer is a mixture of donor material (preferably polymethyl methacrylate, P3HT) and acceptor material (preferably non-fullerene material, ITIC) in a mass ratio of 1:1; the organic semiconductor layer forms a good interfacial contact with the source and drain electrodes, ensuring unobstructed charge transfer channels.

[0062] The source and drain electrodes are made of silver (Ag), with a preferred thickness of 50-100 nm, and are prepared by vacuum thermal evaporation or electron beam evaporation. The silver source and drain electrodes have a smooth and dense surface, which is in close contact with the organic semiconductor, forming a highly efficient charge transfer interface. As the active site of the charge transfer resonance SERS, no additional etching is required to prepare a nano-rough structure.

[0063] (2) such as Figure 3 As shown, the confocal micro Raman spectrometer used in this embodiment includes a laser, a beam expander, a filter, a microscope, a slit, a grating, and a detector;

[0064] The laser is connected to the device sample in sequence via a beam expander, a filter, and a microscope to generate Raman scattered light; the filter is connected to the detector (CCD detector) in sequence via a slit and a grating.

[0065] The laser is used to emit laser light; the beam expander is used to increase the diameter of the laser; the microscope is used to focus the laser light onto the device sample to generate Raman scattered light; the filter is used to filter out stray light and interference light from the Raman scattered light; the slit is used to adjust the luminous flux of the filtered Raman scattered light; the grating is used to split the Raman scattered light; the detector converts the optical signal into an electrical signal and transmits it to an electrical signal detection device to further obtain the Raman spectrum of the device sample.

[0066] In one or more preferred embodiments, the laser wavelength of the Raman microscope is 532 nm, 633 nm, or 785 nm, preferably 785 nm. This wavelength can effectively excite the charge transfer resonance at the silver-organic interface, achieving the best SERS enhancement effect. A laser intensity of 1% is used to avoid photodegradation of the organic semiconductor caused by excessive laser power. The entire channel and interface are scanned, with a scanning area of ​​10 μm × (60 μm ~ 70 μm).

[0067] In one or more preferred embodiments, the confocal micro Raman spectrometer employs an inVia Reflex spectrometer, typically equipped with continuous-wave lasers at wavelengths of 532 nm, 633 nm, and 785 nm, providing stable output. A microscope is used to focus the excitation light onto the device sample and collect the scattered light; a grating separates the Raman scattered light by wavelength to form a spectrum; a higher grating density (e.g., 2400 L / mm vs. 1200 L / mm) results in stronger dispersive power and spectral resolution, but a correspondingly narrower spectral range for a single scan; a detector is used to acquire the optical signal from the scattered light; and a beam expander is used to increase the laser beam diameter to match the objective aperture of the microscope, thereby suppressing diffraction and improving spatial resolution.

[0068] (3) The electrical signal detection device used in this embodiment includes a probe station, a semiconductor parameter analyzer and a computer.

[0069] The probe station is used to place the device sample and apply a bias voltage to the device sample during in-situ Raman testing; the computer is connected to the detectors in the semiconductor parameter analyzer and the confocal micro Raman spectrometer, respectively, and the semiconductor parameter analyzer is connected to the probe station.

[0070] In one or more preferred embodiments, the gate voltage is adjustable from 0V to -30V, and the source-drain bias voltage is adjustable from 0V to -30V. By changing the gate voltage, the carrier concentration in the channel can be adjusted, thereby adjusting the interface charge transfer intensity from the depletion state to the accumulation state, so as to study the interface effect under different carrier concentrations and different charge transfer efficiencies.

[0071] In one or more preferred embodiments, during the in-situ acquisition of Raman spectra, the electrical output characteristics and transfer characteristic curves of the sample device are simultaneously acquired by a semiconductor parameter analyzer, realizing the synchronous acquisition and correlation analysis of electrical signals and optical signals, and directly linking the macroscopic electrical transport performance with the microscopic interface charge transfer and molecular changes.

[0072] In one or more preferred embodiments, before in-situ testing, the laser power and exposure time are evaluated and controlled, the non-uniform region is identified by in-situ Raman imaging, the minimum necessary laser intensity is used, and a platform-moving scanning method is adopted to minimize the impact of laser irradiation on the device sample.

[0073] (4) Confocal imaging technology is used, with a lateral spatial resolution better than 2 μm and a longitudinal resolution of approximately 3 μm, which can effectively detect non-uniform regions and micro-defects in the thin film of the device. The laser power and exposure time are evaluated and controlled. Non-uniform regions are first identified through electroluminescence imaging, the minimum necessary laser intensity is used, and a platform-moving scanning method is employed to minimize the impact of laser irradiation on the device sample. The stability under laser irradiation is crucial for analyzing the degradation mechanism. The laser energy and exposure time need to be adjusted during the experiment to ensure that no macroscopic damage occurs during the measurement process.

[0074] The stability under laser irradiation is crucial for analyzing degradation mechanisms. Experiments require adjustments to laser energy and exposure time to ensure no macroscopic damage occurs during measurement. Based on experience with spectral imaging, the following methods are employed to reduce the influence of the laser and guarantee the reliability of experimental results.

[0075] During imaging, the laser irradiation moves with the automated platform, illuminating different locations on the sample, and the residence time at each location is relatively short. Therefore, compared to in-situ Raman experiments fixed at the same location, laser irradiation causes minimal damage to the sample during imaging. Assuming the laser has a stable output power, the instability effect of the laser spot irradiating different locations on the sample is the same. Therefore, even if systematic errors caused by laser illumination exist throughout the process, the influence of different degradation behaviors on spatial analysis can be eliminated.

[0076] (5) such as Figure 4 Raman spectra of the silicon / silicon dioxide / organic insulating layer / P3HT:ITIC (mass ratio 1:1) / Ag electrode device structure under different wavelength laser scanning at different positions;

[0077] Figure 4 (a) shows the Raman spectrum of the donor material P3HT, the acceptor material ITIC, and the P3HT:ITIC (mass ratio 1:1) blend film under a 532 nm laser; it can be seen that 1378.5 cm⁻¹ -1 The nearby Raman peak i represents the C-ring tensile vibrational mode of P3HT, belonging to the planar inner ring framework mode, which is related to the π-electron delocalization of P3HT; for ITIC, at approximately 1545 cm⁻¹... -1 The characteristic peak terminology at the center of benzene C=C is the vibration of the IDTT peak.

[0078] Figure 4 (b) shows the Raman spectra at different locations, including the metal electrode-semiconductor interface and the channel center, under 785 nm laser scanning. It can be seen that when the 785 nm laser scans the interface between Ag and the active layer, and at the channel edge, there is a significant Raman enhancement compared to the channel center. At the interface region between the silver electrode and the organic semiconductor, the Raman signals of P3HT and ITIC are greatly enhanced due to SERS enhancement dominated by charge transfer resonance, with the intensity of the C=C skeleton vibration peak increasing by approximately 10%. 2 This demonstrates the enhanced effect of charge transfer resonance at the Ag-organic interface, which is on the order of magnitude larger.

[0079] (6) For example Figure 5 Imaging images of the characteristic peak intensities at different positions under different wavelength laser scanning of the silicon / silicon dioxide / organic insulating layer / P3HT:ITIC (mass ratio 1:1) / Ag electrode device structure;

[0080] Figure 5 (a) is a cross-sectional view of the intensity of the characteristic peak of P3HT at the interface between the active layer P3HT:ITIC and the Ag electrode and in the channel under 785 nm and 532 nm laser light. Figure 5 (b) is a Raman image of the intensity of the characteristic peaks of P3HT and ITIC at the metal electrode-semiconductor interface and in the channel under a 785 nm laser. Figure 5 (c) shows the Raman imaging of the P3HT and ITIC characteristic peak intensities at the metal-semiconductor interface and the channel under 532 nm laser light. It can be seen that when using a 785 nm laser for scanning, compared to the 532 nm laser, there is a significant Raman enhancement phenomenon at the channel edge and the metal-semiconductor electrode interface.

[0081] (7) For example Figure 6 Raman images of a silicon / silicon dioxide / organic insulating layer / P3HT:ITIC (mass ratio 1:1) / Ag electrode device structure at different gate voltages with a source-drain voltage of 0V;

[0082] Figure 6 (a) is a Raman image of the intensity of the P3HT characteristic peak at the interface between the active layer P3HT:ITIC and the Ag electrode and the channel when the source-drain voltage is 0V under a 785 nm laser and the gate voltage is applied from -30V to 0V. Figure 6 (b) is a Raman image of the intensity of the ITIC characteristic peak at the interface between the active layer P3HT:ITIC and the Ag electrode and the channel when the source-drain voltage is 0V under a 785nm laser and the gate voltage is applied from -30V to 0V. Figure 6 (c) is a cross-sectional view of the intensity of the characteristic peak of P3HT at the interface between the active layer P3HT:ITIC and the Ag electrode and in the channel under 785 nm laser light. Figure 6 (d) is a cross-sectional view of the ITIC characteristic peak intensity at the interface between the active layer P3HT:ITIC and the Ag electrode and the channel under 785 nm laser light.

[0083] Figure 6 (c) and (d) in the text correspond to respectively Figure 6 The cross-sectional peak intensities in (a) and (b) provide a more intuitive view of the effect of voltage on surface-enhanced Raman scattering (SERS). The pure organic channel region in the middle, lacking metal and interfacial charge transfer, exhibits neither SERS enhancement nor a detectable weak ordinary Raman signal; only the interface shows a strong signal, perfectly achieving selective characterization of the electrode interface. During testing, the source-drain voltage Vd = 0V, the potentials of the source and drain electrodes are identical, the Fermi level positions, injection barriers, and CT resonance matching degrees of the two interfaces are completely consistent, the SERS signals are also perfectly symmetrical, and the two electrode interfaces exhibit homogeneity.

[0084] (8) such as Figure 7 Raman images of a silicon / silicon dioxide / organic insulating layer / P3HT:ITIC (mass ratio 1:1) / Ag electrode device structure at different gate voltages with a source-drain voltage of -30V.

[0085] Figure 7 (a) is a Raman image of the intensity of the P3HT characteristic peak at the interface between the active layer P3HT:ITIC and the Ag electrode and the channel when the source-drain voltage is applied at -30V and the gate voltage is changed from -30V to 0V under a 785 nm laser. Figure 7 (b) shows Raman imaging of the ITIC characteristic peak intensity at the interface between the active layer P3HT:ITIC and the Ag electrode, and in the channel, under a 785 nm laser with a source-drain voltage of -30V and the gate voltage varied from -30V to 0V. From the Raman characteristic peak intensity imaging above, it can be observed that both P3HT and ITIC exhibit significant Raman enhancement at the metal-semiconductor electrode interface.

[0086] Example 4:

[0087] This embodiment provides a method for fabricating a bottom-gate top-contact organic field-effect transistor device according to the above embodiments, including the following steps:

[0088] S1, Clean the substrate.

[0089] S2. An insulating layer is prepared on the cleaned substrate by self-assembly or spin coating.

[0090] S3. An active layer is prepared on the insulating layer by spin coating.

[0091] S4. Prepare metal source and drain electrodes on the active layer using vacuum thermal evaporation.

[0092] In one or more preferred embodiments, step S1 specifically comprises:

[0093] The silicon wafer substrate was sequentially immersed in deionized water, acetone, deionized water, ITO cleaning solution, and ultrasonically cleaned with deionized water for 25-30 minutes each. Then it was boiled at 70-90°C for 7-9 hours in a mixed solution of 98% concentrated sulfuric acid and hydrogen peroxide in a 7:3 volume ratio. After that, it was ultrasonically cleaned with deionized water and isopropanol for 25-30 minutes each. Finally, it was placed in an oven at 60-100°C for drying.

[0094] In one or more preferred embodiments, step S2 specifically comprises:

[0095] Polymethyl methacrylate (PMMA) was spin-coated onto a clean silicon substrate as an organic insulating layer. The PMMA was dissolved in n-butyl acetate (10 mg / mL) and the PMMA layer was prepared at 2000 rpm for 40 s. Then, it was heat-treated at 220 °C for 30 min to induce a crosslinking reaction in the PMMA, resulting in a PMMA layer with a thickness of 50 nm. The entire process was carried out in a glove box.

[0096] In one or more preferred embodiments, step S3 specifically includes:

[0097] An active layer was prepared on a silicon substrate spin-coated with PMMA by solution spin coating. The active layer was P3HT:ITIC (mass ratio 1:1), the solvent was chlorobenzene (CB), and the total concentration of the active layer was 6 mg / ml. Spin coating was performed at 1500 rpm for 40 s. The sample with the prepared organic photosensitive layer was placed on a hot stage and heated at 110 ℃ for 5 min to obtain an active layer of approximately 120 nm. The entire process was completed in a glove box.

[0098] In one or more preferred embodiments, step S4 specifically includes:

[0099] The sample obtained in step S3 was placed inside a mask, and silver (Ag) metal was selected as the source and drain electrodes. The base vacuum for evaporation was 5 × 10⁻⁶. -5 Pa, the initial evaporation rate was 0.04 Å / s to deposit 10 nm first, and then 50~100 nm was deposited at a rate of 0.05 Å / s~0.5 Å / s; the prepared Ag electrode was 1000 μm long and 50 μm wide.

[0100] It should be understood that various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0101] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A novel method for in-situ analysis of electrode interface effects based on surface-enhanced Raman spectroscopy, characterized in that, Includes the following steps: The laser beam from the Raman microscope is incident vertically onto the surface of the bottom-gate top-contact organic field-effect transistor device and focused on the interface region between the source / drain electrodes and the organic semiconductor layer, as well as the center of the channel. In-situ multispectral imaging tests were performed at the metal-semiconductor interface and the center of the channel: gate voltage and source-drain bias voltage were applied, and while the carrier transport state was controlled, the interface Raman spectra and the Raman spectra at the center of the channel were collected in situ under different bias conditions. Based on the changes in peak intensity of in-situ Raman spectra under different bias conditions, the charge transfer, carrier accumulation and interface state effects at the electrode-organic semiconductor interface are analyzed.

2. A novel method for in-situ analysis of electrode interface effects based on surface-enhanced Raman effect according to claim 1, characterized in that, The bottom-gate top-contact organic field-effect transistor device includes, from bottom to top, a gate, an organic insulating layer, an active layer, and source / drain electrodes.

3. A novel method for in-situ analysis of electrode interface effects based on surface-enhanced Raman effect according to claim 2, characterized in that, The gate is made of silicon; the insulating layer is made of polymethyl methacrylate; the active layer is made of a mixture of donor and acceptor materials in a mass ratio of 1:1; and the source and drain electrodes are made of silver.

4. A novel method for in-situ analysis of electrode interface effects based on surface-enhanced Raman effect according to claim 2, characterized in that, The laser beam wavelength of the Raman microscope is 532 nm, 633 nm, or 785 nm.

5. A novel method for in-situ analysis of electrode interface effects based on surface-enhanced Raman effect according to claim 2, characterized in that, The range of the applied gate voltage is 0 V to -30 V, and the range of the source-drain bias voltage is 0 V to -30 V.

6. A novel method for in-situ analysis of electrode interface effects based on surface-enhanced Raman effect according to claim 2, characterized in that, The bottom-gate top-contact organic field-effect transistor device is fabricated through the following steps: Clean the substrate; An insulating layer is prepared on a cleaned substrate by self-assembly or spin coating. An active layer was prepared on the insulating layer by spin coating. Metal source and drain electrodes were fabricated on the active layer using a vacuum thermal evaporation method.

7. A novel method for in-situ analysis of electrode interface effects based on surface-enhanced Raman effect according to claim 1, characterized in that, It also includes the following steps: Before in-situ multispectral imaging testing, in-situ Raman imaging was used to determine the non-uniform region, and the laser power and exposure time were set, using a platform-moving scanning method.

8. A novel system for in-situ analysis of electrode interface effects based on surface-enhanced Raman effect, characterized in that, This includes bottom-gate top-contact organic field-effect transistor devices and in-situ testing systems; The bottom-gate top-contact organic field-effect transistor device includes, from bottom to top, a gate, an organic insulating layer, an active layer, and source / drain electrodes; The in-situ testing system includes a confocal micro Raman spectrometer for acquiring Raman spectra of bottom-gate-top-contact organic field-effect transistor devices and an electrical signal detection device for analyzing Raman spectra.

9. A novel system for in-situ analysis of electrode interface effects based on surface-enhanced Raman effect according to claim 8, characterized in that, The confocal micro Raman spectrometer includes a laser, a beam expander, filters, a microscope, a slit, a grating, and a detector; The laser emitted by the laser is focused onto the bottom-gate top-contact organic field-effect transistor device by passing through a beam expander, a filter, and a microscope in sequence, generating Raman scattered light; the Raman scattered light is received by the detector by passing through a filter, a slit, and a grating in sequence. The detector converts optical signals into electrical signals and transmits them to the electrical signal detection device.

10. A novel system for in-situ analysis of electrode interface effects based on surface-enhanced Raman effect according to claim 8, characterized in that, The electrical signal detection device includes a probe station for placing the bottom-gate top-contact organic field-effect transistor device, a semiconductor parameter analyzer, and a computer. The computer is connected to the semiconductor parameter analyzer and a confocal micro Raman spectrometer, respectively. The semiconductor parameter analyzer is connected to the probe station.

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