Quantum dot light emitting diode electroluminescence imaging method

Abstract

The present application relates to quantum dot light emitting diode (QLED) device characterization technology, in particular to a kind of with quantum dot light emitting diode electroluminescence imaging method.The present application aims to study the relationship between light intensity and dynamic parameter distribution in QLED electroluminescence (EL) process, to guide the preparation optimization of QLED device.The present application successfully realizes the above function by combining function generator with traditional fluorescence imaging system.The innovation of prior art is that function generator is used to generate pulse voltage to excite QLED sample, and fluorescence imaging system is combined to detect the EL imaging of QLED, and the imaging result of EL dynamic parameter is obtained by analysis software fitting.Through the statistics of the spatial distribution of QLED EL dynamic parameter and luminous intensity, the key factors affecting luminous intensity can be identified, thereby effectively guiding the optimization preparation process of QLED device.

Description

Technical Field

[0001] This invention relates to the field of quantum dot light-emitting diode (QLED) device characterization, specifically to a quantum dot light-emitting diode electroluminescence imaging method. Background Technology

[0002] Quantum dot light-emitting diodes (QLEDs), as a novel type of optoelectronic device, have attracted much attention due to their excellent luminous performance, wide color gamut, and good stability. In the fields of display technology and lighting, QLEDs, with their high photoelectric conversion efficiency and low power consumption, are gradually becoming strong competitors to traditional light-emitting diodes (LEDs) and organic light-emitting diodes (OLEDs). However, despite the significant progress made in QLED technology in recent years, improving its electroluminescence (EL) performance still faces many challenges.

[0003] The performance of QLED devices is typically influenced by multiple factors, including material selection, device structure design, and fabrication process optimization. Existing research primarily focuses on improving the quantum efficiency of luminescent materials and the overall stability of the devices, but studies on the relationship between QLED luminescence intensity and luminescence kinetic parameters are relatively limited. This lack of sufficient data to support the optimization of QLED device performance ultimately impacts the final device's performance.

[0004] Existing characterization techniques mostly rely on single measurement methods, making it difficult to fully reflect the complexity of the QLED light emission process. For example, traditional imaging techniques can only provide spatial distribution information of luminous intensity, but cannot record the EL dynamics distribution of QLEDs. Methods for probing the EL dynamics of QLED devices, such as photodiode or single-photon techniques, can only detect the overall EL dynamics of the device, not its spatial distribution. Therefore, existing research lacks a deep understanding of these key parameters, making it difficult to formulate scientifically sound fabrication schemes during the optimization of QLED devices.

[0005] Therefore, there is an urgent need for a novel characterization method that can comprehensively consider the relationship between luminescence intensity and kinetic parameters, in order to provide a more reliable basis for optimizing the performance of QLED devices. This invention proposes an effective method for characterizing the luminescence intensity and kinetic parameter distribution of QLEDs by combining a function generator with a traditional fluorescence imaging system. This method can not only acquire the electroluminescence characteristics of QLEDs in real time, but also provide a scientific basis for the optimized fabrication of QLED devices by analyzing the relationship between the obtained kinetic parameters and luminescence intensity. This technology will help promote the further development of QLED technology and lay the foundation for its widespread application in high-performance displays and lighting applications. Summary of the Invention

[0006] The purpose of this invention is to provide a quantum dot light-emitting diode electroluminescence imaging method, which aims to solve the problem in the prior art that it is impossible to simultaneously obtain the electroluminescence (EL) dynamics and luminescence intensity distribution of QLED devices.

[0007] The technical solution adopted by the present invention to achieve the above objectives is as follows:

[0008] The quantum dot light-emitting diode electroluminescence imaging method includes the following steps:

[0009] 1) Connect the fluorescence imaging system to the function generator using a galvanometer card;

[0010] 2) Use a function generator to generate pulse voltages of specific frequency and amplitude to excite the QLED sample;

[0011] 3) The electroluminescent EL of the QLED is imaged and detected using a fluorescence imaging system;

[0012] 4) Fit the EL imaging results to obtain the EL dynamic parameters and analyze their relationship with the luminescence intensity.

[0013] Step 1) specifically refers to:

[0014] The galvanometer card controls the galvanometer to perform spatial scanning of the quantum dot light-emitting diode (QLED) sample. During the scanning process, whenever the scan enters the next pixel, the galvanometer card simultaneously outputs a pulse signal through a time-correlated single-photon counting system. The period of the pulse signal is consistent with the dwell time at each pixel. The pulse signal is used as a trigger source to trigger the function generator, making it synchronized with the pixel scanning in fluorescence imaging.

[0015] The pulse voltage in step 2) is a square pulse wave with adjustable pulse width, amplitude, rising edge, and falling edge.

[0016] Step 3) includes the following steps:

[0017] 3.1) The light emitted by the QLED is collected by the objective lens of the microscope, and under the action of the scanning lens in the microscope and fluorescence imaging system, it hits the scanning galvanometer, and the light outside the focal plane is filtered through the pinhole behind the scanning galvanometer.

[0018] 3.2) Change the angle of the scanning galvanometer and repeat step 3.1) to complete the scanning of each position on the QLED sample and record the time coordinate and spatial coordinate of each photon, thereby obtaining the EL dynamic curve and EL emission intensity of each point on the QLED sample.

[0019] Step 4) specifically involves:

[0020] The EL dynamics curve at each pixel is fitted to obtain the dynamic parameters in the EL dynamics curve, including initial delay, rise time, decay time, and luminous intensity. Then, the spatial distribution of the dynamic parameters is obtained. By statistically analyzing the spatial distribution of EL dynamic parameters and luminous intensity, the key factors affecting luminous intensity are identified.

[0021] The present invention has the following beneficial effects and advantages:

[0022] 1. This invention can simultaneously obtain the spatial distribution of luminous intensity and EL dynamics of QLED devices, providing more comprehensive data support.

[0023] 2. This invention provides a scientific basis for the optimized fabrication of QLED devices by analyzing the relationship between kinetic parameters and luminous intensity, thereby improving device performance.

[0024] 3. The technical solution of this invention can be widely applied to the research and development of QLED devices, providing strong support for improving their application in high-performance display and lighting fields. Attached Figure Description

[0025] Figure 1 Schematic diagram of electroluminescence imaging principle;

[0026] Figure 2 Figure showing experimental results of testing QLED devices using an electroluminescence imaging system;

[0027] Figure 3 A schematic diagram of the EL dynamics extracted from a specific pixel;

[0028] Figure 4 Fitting results of EL dynamic parameters at various points (rising edge);

[0029] Figure 5 The fitting results of the EL dynamic parameters at various points (falling edge). Detailed Implementation

[0030] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0031] A quantum dot light-emitting diode electroluminescence imaging method includes the following steps:

[0032] The fluorescence imaging system is coupled with the function generator using a synchronization signal;

[0033] A function generator is used to generate pulse voltages of specific frequency and amplitude to excite the QLED sample;

[0034] The electroluminescence (EL) of the QLED was imaged and detected using a fluorescence imaging system;

[0035] The EL imaging results were fitted using analysis software to obtain EL dynamic parameters and analyze their relationship with luminescence intensity.

[0036] The frequency and amplitude of the pulse voltage can be adjusted according to actual needs.

[0037] By statistically analyzing the spatial distribution of the EL dynamic parameters and luminescence intensity, key factors affecting luminescence intensity are identified.

[0038] like Figure 1 As shown, a system for optimizing the fabrication of quantum dot light-emitting diode (QLED) devices, the system comprising:

[0039] A function generator is used to generate pulse voltages to excite the QLED sample and adjust the excitation parameters.

[0040] Traditional fluorescence imaging systems are used for real-time detection of the QLED's EL imaging.

[0041] Analysis software is used to fit EL imaging results and statistically analyze dynamic parameters to provide spatial distribution information of luminescence intensity.

[0042] The analysis software can generate spatial distribution maps of QLED EL dynamic parameters and luminous intensity.

[0043] Example 1

[0044] like Figures 2-5 As shown, a quantum dot light-emitting diode electroluminescence imaging method includes the following steps:

[0045] 1) A square QLED sample with a side length of 2 mm was placed on an inverted microscope (Olympus, IX-81) connected to a time-correlated single-photon counting system (Becker & Hickl, SPC-150) to enable observation and testing of the device.

[0046] 2) In the system, the Multi-Channel Expansion (MCS) mode is selected, which ensures the time window meets the requirements for testing QLEDs. Furthermore, we control the galvanometer for spatial scanning using a galvanometer card (GVD-150) connected to the SPC-150. During the process, as the scan moves to the next pixel, the galvanometer card simultaneously outputs a pulse signal via the SPC-150 system, with a period matching the dwell time at each pixel. Here, we set the dwell time at each pixel to 1 millisecond.

[0047] 3) Use the pulse signal from step 2 as a trigger source to trigger the function generator (Tektronix, AFG31102) to synchronize it with the pixel scanning in fluorescence imaging. At this time, the function generator will output a pulse waveform for each pixel scanned during the scanning process, with a period of 1 millisecond, which is the same as the pixel dwell time.

[0048] 4) Set the pulse waveform output from the function generator to a square pulse with adjustable pulse width, amplitude, rise time, and fall time. For the QLED we are testing here, we set the pulse width to 20 microseconds, the voltage amplitude to 3 volts, and both the rise time and fall time to -4 nanoseconds. We then use this pulse voltage to excite the QLED sample and light it up.

[0049] 5) The light emitted by the QLED is collected by the microscope objective lens and, under the action of the scanning lens in the microscope and fluorescence imaging system, is projected onto the scanning galvanometer. The light outside the focal plane is then filtered through a pinhole behind the scanning galvanometer. By changing the angle of the scanning galvanometer, scanning of various locations on the QLED sample can be achieved.

[0050] 6) The light passing through the pinhole is detected by a single-photon detector in the fluorescence imaging system. In MCS mode, the time of photon detection within one pulse cycle can be recorded, thus achieving temporal resolution of QLED emission. Furthermore, in MCS mode, multiple photons can be recorded per cycle, improving acquisition efficiency. The position information of each photon is recorded by a galvanometer card, allowing us to simultaneously record the temporal and spatial coordinates of each photon during QLED emission. By accumulating data from multiple scans, a large number of photons are recorded, enabling us to obtain the EL dynamics curve and EL emission intensity at each point on the QLED sample.

[0051] 7) Import the data into the analysis software and fit the EL dynamics curve at each pixel point. This will allow you to obtain the dynamic parameters such as initial delay, rise time, and decay time in the EL dynamics curve, and thus obtain the spatial distribution of these dynamic parameters.

Claims

1. A quantum dot light-emitting diode electroluminescence imaging method, characterized in that, Includes the following steps: 1) Connect the fluorescence imaging system to the function generator using a galvanometer card; 2) Use a function generator to generate pulse voltages of specific frequency and amplitude to excite the QLED sample; 3) The electroluminescent EL of the QLED is imaged and detected using a fluorescence imaging system; 4) Fit the EL imaging results to obtain the EL dynamic parameters and analyze their relationship with the luminescence intensity.

2. The quantum dot light-emitting diode electroluminescence imaging method according to claim 1, characterized in that, Step 1) specifically refers to: The galvanometer card controls the galvanometer to perform spatial scanning of the quantum dot light-emitting diode (QLED) sample. During the scanning process, whenever the scan enters the next pixel, the galvanometer card simultaneously outputs a pulse signal through a time-correlated single-photon counting system. The period of the pulse signal is consistent with the dwell time at each pixel. The pulse signal is used as a trigger source to trigger the function generator, making it synchronized with the pixel scanning in fluorescence imaging.

3. The quantum dot light-emitting diode electroluminescence imaging method according to claim 1, characterized in that, The pulse voltage in step 2) is a square pulse wave with adjustable pulse width, amplitude, rising edge, and falling edge.

4. The quantum dot light-emitting diode electroluminescence imaging method according to claim 1, characterized in that, Step 3) includes the following steps: 3.1) The light emitted by the QLED is collected by the objective lens of the microscope, and under the action of the scanning lens in the microscope and fluorescence imaging system, it hits the scanning galvanometer, and the light outside the focal plane is filtered through the pinhole behind the scanning galvanometer. 3.2) Change the angle of the scanning galvanometer and repeat step 3.1) to complete the scanning of each position on the QLED sample and record the time coordinate and spatial coordinate of each photon, thereby obtaining the EL dynamic curve and EL emission intensity of each point on the QLED sample.

5. The quantum dot light-emitting diode electroluminescence imaging method according to claim 1, characterized in that, Step 4) specifically involves: The EL dynamics curve at each pixel is fitted to obtain the dynamic parameters in the EL dynamics curve, including initial delay, rise time, decay time, and luminous intensity. Then, the spatial distribution of the dynamic parameters is obtained. By statistically analyzing the spatial distribution of EL dynamic parameters and luminous intensity, the key factors affecting luminous intensity are identified.

Images