A novel thin-film quantum yield testing device and its quantum yield testing method

Abstract

The present invention provides a novel thin-film quantum yield testing device and a quantum yield testing method thereof. Based on the photoelectric effect, in an ultra-high vacuum environment, an ultraviolet light is emitted by an LED light source to irradiate the surface of a sample. An optical integrating sphere is used to collect photoelectrons and convert them into an electrical signal for output. An electrometer is used to achieve the acquisition and processing of high-resolution electrical signals, and a bias voltage is applied through a source meter between the integrating sphere and the electrometer to control the magnitude of the photocurrent. Finally, the work function of the sample surface is obtained from the positive bias voltage required when the photocurrent drops to zero, and the quantum yield of the sample is obtained based on the saturated photocurrent under the action of the applied bias voltage and the calibrated surface ultraviolet light intensity. The present invention realizes the precise measurement of photocurrent in an ultra-high vacuum environment, can well meet the requirements of accurate measurement of the quantum yield of the thin-film surface, and has strong practical application value.

Description

Technical Field

[0001] The present invention relates to the field of display technology, and particularly to a novel thin film quantum yield testing device and a quantum yield testing method thereof. Background Art

[0002] The charge management system of an inertial sensor mainly utilizes the fact that gold on the inner surface of the inertial sensor generates photoelectrons under ultraviolet light irradiation, controls the photoelectrons to deviate from or be incident on the test mass, thereby realizing the charge control of the test mass, and is one of the important components of the satellite platform's drag-free control. It provides necessary data for the spacecraft to maintain its inertial orbit. At the same time, the measurement of the test mass ground wire is one of the important conditions for gravitational wave detection. In space gravitational wave detection, the main payload of the inertial sensor carried by the satellite is one or two Au-plated metal block objects (test masses). The reference benchmark of the inertial sensor requires that the trajectory moves without drag along the geodesic, and it is required that the noise received by the test mass is lower than the detection index. Due to the ionization radiation caused by high-energy cosmic rays in deep space, a large amount of charge will accumulate on the surface area of the test mass, causing the test mass to be interfered by electromagnetic force, thereby masking the signal of gravitational wave detection. This is a main noise source in space gravitational wave detection.

[0003] The quantum yield of the surface of the gold-plated material of the inertial sensor can be directly measured by the method of surface photoemission. The technology of this method is based on the photoelectric effect and is an effective and simple characterization means for exploring the surface information of samples. The photoelectric effect refers to the physical effect that a light beam irradiates a metal material, causing it to emit electrons. The emitted electrons are called "photoelectrons". To emit photoelectrons, the electrons must obtain enough energy to overcome the binding of the metal material (work function / escape work). The energy obtained by an electron in the metal absorbing a photon is, and a part of this energy is used to overcome the work function of the metal (work function), and the other part is manifested as the maximum initial kinetic energy K of the emitted photoelectrons max =mv 2 . The photoelectric effect is the basic method to change the charge state in the inertial sensor. To excite photoelectrons, the detection surface of the sensor must be illuminated by light with a high enough frequency. Due to the existence of the photoelectric effect, when irradiated by electromagnetic waves at a specific frequency, the electrons on the surface of the inertial sensor material absorb energy and escape as photoelectrons, forming a photocurrent. By testing the photocurrent generated on the surface of the inertial sensor material by this method, the surface work function can be obtained while also obtaining the quantum yield value, which is an effective characterization means for in-situ exploring the surface quantum yield of samples. Such a device for measuring the surface quantum yield of samples is very rare but widely used.

[0004] Therefore, as researchers, we expect to design a device that can efficiently and accurately measure the surface quantum yield and surface work function of samples and apply it to inertial sensors.

[0005] The present invention is used to measure the quantum yield of the gold-plated surface of an inertial sensor. Its principle is based on the photoelectric effect and can achieve precise measurement of photocurrent in an ultra-high vacuum environment. Therefore, it can well meet the needs of measuring the quantum yield in scientific research and production and has strong practical application value. Summary of the Invention

[0006] The present invention is used to measure the quantum yield of the thin film surface. This device is based on the photoelectric effect. By adjusting the wavelength, power, scattering angle, incident angle of the incident light, and the magnitude of the applied bias voltage, precise measurement of the quantum yield and surface work function of the sample surface can be achieved. Based on this, we designed a device for measuring the quantum yield of the thin film sample surface based on the photoelectric effect. This device is based on the photoelectric effect. In an ultra-high vacuum environment, ultraviolet light is emitted to irradiate the sample surface. An optical integrating sphere is used to collect photoelectrons and convert them into electrical signals for output. An electrometer is used to collect and process high-resolution electrical signals. A bias voltage is applied through a source meter between the integrating sphere and the electrometer to control the magnitude of the photocurrent. Finally, the work function of the sample surface is obtained from the positive bias voltage required when the photocurrent drops to zero. The quantum yield of the sample is obtained based on the saturated photocurrent under the action of the applied bias voltage and the calibrated surface ultraviolet light intensity. A layer of gold is plated on the surface of the entire test mass and all electrodes and the outer shell. The gold-plated surface of the inner outer shell is illuminated with ultraviolet light to add negative charges to the test mass, or the gold-plated surface of the test mass itself is illuminated to remove negative charges. Charge management is achieved through this non-contact method without disturbing the free-fall purity of the test mass.

[0007] The present invention mainly solves the problem of precise measurement of the quantum yield of the gold-plated surface of an inertial sensor and can explore the influence of the optical characteristics of the incident light (scattering angle, power, incident angle) on the quantum yield by changing the optical characteristics of the incident light.

[0008] The purpose of the present invention is to provide a new type of thin film quantum yield testing device, including: a vacuum chamber, in which there are provided: an optical integrating sphere, a source meter, and an electrometer;

[0009] The outer side of the first side wall of the optical integrating sphere is fixed in the vacuum chamber through an integrating sphere bracket. The second side wall of the optical integrating sphere is provided with an LED light source track, and a Micro-LED light source is arranged on the LED light source track. The Micro-LED light source is slidably connected to the LED light source track;

[0010] The inner side of the third side wall of the optical integrating sphere is provided with a sample bracket, and the sample bracket includes a connecting part and a sample placing part. The connecting part is connected to the inner side of the third side wall of the optical integrating sphere;

[0011] The sample placement part carries a sample. The electrometer is arranged outside the optical integrating sphere and is electrically connected to the sample. The source meter is arranged outside the optical integrating sphere and is electrically connected between the electrometer and the optical integrating sphere.

[0012] Furthermore, in the present invention, the track length of the LED light source is 8 - 16 cm, and the incident angle range of the LED light source is -45° to 45°. The LED light source track can be used to adjust the position of the LED light source. By changing the position of the LED light source, the incident angle can be changed, and then the effective illumination area can be changed to explore the influence of the effective illumination area of the incident light on the surface quantum yield and surface work function of the sample. When the incident angle is lower than the lower limit value, the effective area irradiated on the sample surface is too small, resulting in too few emitted photoelectrons, and the electrical signal level output by the integrating sphere is too small, exceeding the recognition range of the electrometer, and the effective detection of the quantum yield cannot be achieved. When the incident angle is higher than the upper limit, the effective area irradiated on the sample surface is too large, resulting in too many emitted photoelectrons, and the electrical signal level output by the integrating sphere is too large, greater than the measurement range of the electrometer, which may cause damage to the instrument and the effective detection of the quantum yield cannot be achieved.

[0013] Furthermore, in the present invention, the wavelength adjustment range of the LED light source is 250 nm to 275 nm; the divergence angle adjustment range of the LED light source is 45° to 135°. When the divergence angle is large, the degree of light dispersion is large, resulting in a low beam intensity and not being able to excite enough photoelectrons. The electrical signal level output by the integrating sphere is too small, exceeding the recognition range of the electrometer, and the effective detection of the quantum yield cannot be achieved. When the divergence angle is small, the degree of light dispersion is small, resulting in a large beam intensity and too many emitted photoelectrons. The electrical signal level output by the integrating sphere is too large, greater than the measurement range of the electrometer, which may cause damage to the instrument and the effective detection of the quantum yield cannot be achieved.

[0014] Furthermore, in the present invention, the vacuum pressure of the vacuum chamber ≥ 10 -5 Pa, the source meter applies a bias voltage, and it is powered by a battery. Using battery power can effectively avoid AC noise. Combined with the integrating sphere, it can achieve ultrasensitive detection of photoelectrons and fully meet the current resolution requirements for accurate quantum yield. To achieve precise measurement of the quantum yield, the current resolution should be better than 0.01 fA (0.01 x 10-15 A).

[0015] Further, the test range of the source meter in the present invention is -10 V to 10 V, and the resolution is 100 nV to 200 nV. During the test, the magnitude of the photocurrent is controlled by changing the magnitude of the bias voltage, so as to obtain the surface work function and the surface quantum yield of the sample. When the bias voltage is lower than the lower limit value, the photocurrent is too small, and the magnitude of the electrical signal output by the integrating sphere is too small, exceeding the recognition range of the electrometer, and the effective detection of the quantum yield cannot be realized; when the bias voltage is higher than the upper limit value, the photocurrent is too large, and the magnitude of the electrical signal output by the integrating sphere is too large, greater than the measurement range of the electrometer, which may cause damage to the instrument, and the effective detection of the quantum yield cannot be realized.

[0016] Further, in the present invention, the material of the sample holder is polyether ether ketone, and the resistance of the sample holder is ≥10 9 MΩ. The polyether ether ketone material has a relatively high resistivity, which can effectively prevent the influence of the sample holder itself on the test results.

[0017] Further, in the present invention, the diameter of the optical integrating sphere is 5 to 15 inches. The optical integrating sphere is used to collect the photoelectrons emitted by the anode.

[0018] The present invention also provides a new method for testing the quantum yield of a thin film, including:

[0019] (1) Place the sample to be tested on the sample placement part of the sample holder of the above-mentioned new thin film quantum yield testing device;

[0020] (2) Check the cleanliness and vacuum degree inside the optical integrating sphere cavity;

[0021] (3) Turn on the LED light source and set the optical parameters;

[0022] (4) Set the voltage parameters: adjust the magnitude of the bias voltage of the source meter to control the magnitude of the photocurrent;

[0023] (5) Calculate the work function and quantum yield of the sample.

[0024] Further, in the quantum yield testing method of the present invention, the setting of the light source parameters includes: adjusting the frequency, divergence angle, incident angle, power of the LED light source, and adjusting the orbit of the LED light source.

[0025] Specifically, it includes the following content:

[0026] Ⅰ. Adjust the frequency of the LED light source to reach the limiting frequency of the photoelectric effect, and photoelectrons are emitted from the surface of the irradiated sample to form a photocurrent;

[0027] Ⅱ. Adjust the divergence angle of the LED light source to explore the influence of the incident light power and the scattering angle on the surface quantum yield and work function of the sample, and explore the optimal divergence angle;

[0028] Ⅲ. Adjust the LED light source track, change the incident angle of the LED light source, explore the influence of the effective irradiation area of the incident light on the surface quantum yield and surface work function of the sample, and explore the optimal incident angle;

[0029] Ⅳ. Adjust the power of the LED light source, explore the influence of the incident light power on the overall quantum yield, and explore the optimal power.

[0030] Furthermore, in the quantum yield test method of the present invention, the setting of the voltage parameters includes: when the incident light is constant, the magnitude of the applied bias voltage can be changed to regulate the magnitude of the photocurrent. In this process, the change of the quantum yield under different applied bias voltages can be explored. At the same time, observe the reading of the electrometer and read the data for subsequent calculation of the quantum yield; by changing the magnitude of the bias voltage to control the magnitude of the photocurrent, and then calculate the surface work function and surface quantum yield of the sample.

[0031] The calculation of the work function and quantum yield of the sample includes:

[0032] Work function = incident photon energy - maximum initial kinetic energy of photoelectrons

[0033] The magnitude of the positive bias corresponding to the reduction of the photocurrent to zero corresponds to the maximum initial kinetic energy of the photoelectrons;

[0034] Quantum yield: The quantum yield can be obtained according to the saturated photocurrent under the action of the applied bias voltage and the calibrated surface ultraviolet light intensity.

[0035] The quantum yield refers to the probability of a chemical reaction occurring after the photon energy is absorbed in a photoreaction. It is an important physical quantity that can be used to evaluate the efficiency and rate of photoreactions.

[0036] The calculation formula of the quantum yield is as follows:

[0037]

[0038] Among them, η is the quantum yield, Jph is the saturated photocurrent (unit: mA), P is the calibrated surface ultraviolet light intensity (unit: mW / cm 2 ), λ is the wavelength of the light source, h is Planck's constant, c is the speed of light, e is the electron charge, A is a constant, and A = 1 (unit: J·cm / V).

[0039] The quantum yield can also be obtained by the following calculation formula:

[0040] Ф = (Np - Np') / Np

[0041] Among them, Ф represents the quantum yield, Np represents the number of absorbed photons, and Np' represents the number of unabsorbed photons. The meaning of this formula is that the quantum yield is equal to the ratio of the difference between the number of absorbed photons and the number of unabsorbed photons to the number of absorbed photons.

[0042] Calculating the quantum yield requires knowing the number of absorbed photons and the number of unabsorbed photons. The number of photons can be calculated from the light intensity and the reaction volume. The number of unabsorbed photons can be calculated by measuring the light intensity before and after the reaction.

[0043] In practical applications, methods such as colorimetry, fluorescence, or radioactive isotope methods are usually used to measure the light intensity and reaction rate, thereby calculating the quantum yield.

[0044] Compared with the prior art, the present invention has the following beneficial technical effects:

[0045] The novel thin-film quantum yield testing device described in the present invention realizes precise measurement of photocurrent in an ultra-high vacuum environment, can well meet the requirements of accurate measurement of the quantum yield on the thin-film surface, and has strong practical application value.

[0046] (1) The vacuum pressure of the test environment is ≥10-5 Pa, which can effectively avoid the influence of environmental pollution on the measurement results, realize accurate measurement of the quantum yield, and the measurement error of the method described in the present invention is less than ±2%;

[0047] (2) The sample holder material uses a high-resistivity material, polyether ether ketone, with a resistance of up to 10 9 MΩ or more, which can effectively prevent the influence of the sample holder itself on the test results; when the resistance level is less than MΩ, there may be a leakage phenomenon in the sample holder, resulting in inaccurate electrometer readings and affecting the accurate detection of the quantum yield;

[0048] (3) The electrometer is powered by a battery, effectively avoiding AC noise, and combined with an integrating sphere, ultra-sensitive detection of photoelectrons can be achieved;

[0049] (4) The LED light source track can be used to adjust the position of the LED light source. By changing the position of the LED light source, the incident angle can be changed, and then the effective irradiation area can be changed to explore the influence of the effective irradiation area of the incident light on the quantum yield and surface work function of the sample surface;

[0050] (5) The light source uses an LED light source, whose power and scattering angle are adjustable, and the influence of the incident light power and scattering angle on the surface work function and quantum yield of the sample surface can be explored.

[0051] (6) During the test, the source meter controls the magnitude of the photocurrent by changing the magnitude of the bias voltage, and then obtains the surface work function and the surface quantum yield of the sample. Description of the Drawings

[0052] Figure 1 Schematic diagram of the novel thin-film quantum yield testing device of the present invention;

[0053] Wherein: 1. Vacuum chamber, 2. LED light source, 3. LED light source track, 4. Sample, 5. Sample holder, 6. Electrometer, 7. Source meter, 8. Optical integrating sphere, 9. Integrating sphere holder. Specific implementation manners

[0054] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the present invention. Specific implementation manner one

[0056] A novel thin-film quantum yield testing device of the present invention includes:

[0057] Vacuum chamber, inside which are provided: an optical integrating sphere, a source meter and an electrometer;

[0058] The outside of the first side wall of the optical integrating sphere is fixed inside the vacuum chamber through an integrating sphere holder. The second side wall of the optical integrating sphere is provided with an LED light source track, and an LED light source is arranged on the LED light source track. The LED light source and the LED light source track are slidably connected;

[0059] The inside of the third side wall of the optical integrating sphere is provided with a sample holder, and the sample holder includes a connecting part and a sample placing part. The connecting part is connected to the inside of the third side wall of the optical integrating sphere;

[0060] The sample placing part carries a sample. The electrometer is arranged outside the optical integrating sphere and is electrically connected to the sample; the source meter is arranged outside the optical integrating sphere and is electrically connected between the electrometer and the optical integrating sphere.

[0061] The length of the LED light source track is 8 - 16 cm, and the incident angle range of the LED light source is -45° to 45°.

[0062] The wavelength of the LED light source is adjustable, and the adjustment range is 250 nm to 275 nm; the divergence angle of the LED light source is adjustable, and the adjustment range is 45° to 135°.

[0063] The vacuum pressure of the vacuum chamber ≥ 10 -5 Pa, the source meter applies a bias voltage and is powered by a battery.

[0064] The test range of the source meter is -10 V to 10 V, and the resolution is 100 nV to 200 nV.

[0065] The material of the sample holder is polyether ether ketone, and the resistance of the sample holder is ≥ 10 9 MΩ.

[0066] The diameter of the optical integrating sphere is 5 - 15 inches. Specific Embodiment 2

[0068] A new method for testing the quantum yield of thin films according to the present invention includes:

[0069] (1) Place the sample to be tested in the sample placement part of the sample holder of the above-mentioned new thin film quantum yield testing device;

[0070] (2) Check the cleanliness and vacuum degree inside the optical integrating sphere cavity;

[0071] (3) Turn on the LED light source and set the optical parameters;

[0072] (4) Set the voltage parameters: adjust the magnitude of the bias voltage of the source meter to control the magnitude of the photocurrent;

[0073] (5) Calculate the work function and quantum yield of the sample.

[0074] The above setting of the light source parameters includes:

[0075] Ⅰ. Adjust the frequency of the LED light source to reach the limiting frequency of the photoelectric effect, and photoelectrons are emitted from the surface of the irradiated sample to form a photocurrent;

[0076] Ⅱ. Adjust the divergence angle of the LED light source to explore the influence of the incident light power and the scattering angle on the quantum yield and work function of the sample surface, and explore the optimal divergence angle;

[0077] Ⅲ. Adjust the LED light source orbit to change the incident angle of the LED light source, and explore the influence of the effective irradiation area of the incident light on the quantum yield and surface work function of the sample surface, and explore the optimal incident angle;

[0078] Ⅳ. Adjust the power of the LED light source to explore the influence of the incident light power on the overall quantum yield, and explore the optimal power.

[0079] (Setting the voltage parameters includes: when the incident light is constant, the magnitude of the externally applied bias voltage can be changed to control the magnitude of the photocurrent. This process can explore the change of the quantum yield under the action of different externally applied bias voltages. At the same time, observe the reading of the electrometer and read the data for subsequent calculation of the quantum yield; by changing the magnitude of the bias voltage to control the magnitude of the photocurrent, and then calculate the surface work function and surface quantum yield of the sample.)

[0080] The above calculation of the work function and quantum yield of the sample includes:

[0081] Work function = incident photon energy - maximum initial kinetic energy of photoelectrons

[0082] The magnitude of the positive bias required when the photocurrent decreases to zero corresponds to the maximum initial kinetic energy of the photoelectrons;

[0083] Quantum yield: The quantum yield can be obtained based on the saturated photocurrent under the action of the applied bias voltage and the calibrated surface ultraviolet light intensity.

[0084] The calculation formula for the quantum yield is as follows:

[0085]

[0086] Among them, η is the quantum yield, Jph is the saturated photocurrent (unit: mA), P is the calibrated surface ultraviolet light intensity (unit: mW / cm 2 ), λ is the wavelength of the light source, h is Planck's constant, c is the speed of light, e is the electron charge, A is a constant, and A = 1 (unit: J·cm / V).

[0087] To enable those skilled in the art to clearly understand the above implementation details and operations of the present invention, and to significantly reflect the quantum yield measurement device corresponding to the embodiments of the present invention and the measurement method of the quantum yield, the above technical solutions are illustrated by examples below. Example 1:

[0088] A novel thin-film quantum yield test device of the present invention, referring to Figure 1 , includes: a vacuum chamber 1, and disposed inside the vacuum chamber 1 are: an optical integrating sphere 8, a source meter 7, and an electrometer 6; the outer side of the first side wall of the optical integrating sphere 8 is fixed inside the vacuum chamber through an integrating sphere bracket 9, the second side wall of the optical integrating sphere 8 is provided with an LED light source track 3, an LED light source 2 is disposed on the LED light source track 3, and the LED light source 2 is slidably connected to the LED light source track 3; the inner side of the third side wall of the optical integrating sphere 8 is provided with a sample holder 5, the sample holder 5 includes a connecting portion and a sample placing portion, and the connecting portion is connected to the inner side of the third side wall of the optical integrating sphere 8; the sample placing portion carries a sample 4, the electrometer 6 is disposed outside the optical integrating sphere 8 and is electrically connected to the sample 4; the source meter 7 is disposed outside the optical integrating sphere 8 and is electrically connected between the electrometer 6 and the optical integrating sphere 8.

[0089] The length of the LED light source track 3 is 10 cm, and the incident angle range of the LED light source 2 is -45° to 45°. The wavelength adjustment range of the LED light source 2 is 250 nm to 275 nm; the divergence angle adjustment range of the LED light source 2 is 45° to 135°. The vacuum pressure of the vacuum chamber 1 ≥ 10 -5pa, a bias voltage is applied to the source meter 7, which is powered by a battery. The test range of the source meter 7 is -10V to 10V, and the resolution is 100 nV to 200. The material of the sample holder 5 is polyether ether ketone, and the resistance of the sample holder 5 is ≥ 10 9 MΩ. The diameter of the optical integrating sphere 8 is 10 inches.

[0090] In this Embodiment 1, the source meter 7 is a Keithley 2612B source meter, the electrometer 6 is a Keysight B2987B electrometer, and the LED light source is a Micro-LED lamp produced by Fudan University. Embodiment 2:

[0091] A new method for testing the quantum yield of thin films specifically includes the following steps:

[0092] Step 1: Preparation before testing. Place the sample 4, check the power supply of the device, whether the vacuum degree meets the requirements, check the cleanliness inside the cavity to prevent contamination of the sample 4; use a vacuum gauge to detect whether the vacuum requirement is met. Use a vacuum gauge to detect whether the vacuum requirement is met, and the vacuum is better than 10 -5 pa; use a particle counter to detect whether the cleanliness level is reached, and the ultra-clean level reaches a 10,000-class ultra-clean room; the power supply device needs to work under a regulated voltage state.

[0093] Step 2: Light source parameter setting. Turn on the LED light source 2, adjust the frequency of the LED light source 2 to reach the threshold frequency of the photoelectric effect. At this time, photoelectrons will escape from the surface of the irradiated sample 4, forming a photocurrent. Next, the divergence angle of the LED light source can be adjusted to explore the influence of the incident light divergence angle on the quantum yield and find the optimal divergence angle; adjust the LED light source orbit to change the incident angle and explore the influence of the effective irradiation area of the incident light on the overall quantum yield to find the optimal incident angle; adjust the power of the LED light source to explore the influence of the incident light power on the overall quantum yield and find the optimal power; in this Embodiment 2, the threshold frequency of the LED light source 2 to reach the photoelectric effect is 7.5×10 15 Hz, the optimal divergence angle of the LED light source 2 is 60°, the optimal incident angle of the LED light source 2 is 45°, and the optimal power of the LED light source 2 is 3.95E-4 W.

[0094] Step 3: Voltage parameter setting. When the incident light of the LED light source 2 is constant, the magnitude of the externally applied bias voltage can be changed to control the magnitude of the photocurrent. This process can explore the change of the quantum yield under the action of different externally applied bias voltages. At the same time, observe the reading of the electrometer and read the data for subsequent calculation of the quantum yield;

[0095] Step 4: End the test and calculate the work function and quantum yield. The work function is obtained from the positive bias voltage required when the photocurrent decreases to zero. The magnitude of the positive bias voltage required for the photocurrent to decrease to zero corresponds to the maximum initial kinetic energy of the photoelectrons. Subtracting the maximum initial kinetic energy of the photoelectrons from the incident photon energy hv gives the work function of the material.

[0096] In this Example 2, the incident photon energy hv is 4.88 eV, the maximum initial kinetic energy of the photoelectrons is 0.68 eV, and finally the work function of the material is obtained as 4.2 eV.

[0097] The quantum yield is mainly obtained by measuring the photocurrent generated by surface photoemission under certain conditions. The quantum yield can be obtained based on the saturated photocurrent under the applied bias voltage and the calibrated surface ultraviolet light intensity.

[0098] The calculation formula for the quantum yield is as follows:

[0099]

[0100] where η is the quantum yield, Jph is the saturated photocurrent (unit: mA), P is the calibrated surface ultraviolet light intensity (unit: mW / cm 2 ), λ is the wavelength of the light source, h is Planck's constant, c is the speed of light, e is the electron charge, and A is a constant, A = 1 (unit: J·cm / V). In this Example 2, the measurement conditions are to reach the standard vacuum degree, cleanliness, and stable instrument state. The saturated photocurrent is 10 -2 mA, the calibrated surface ultraviolet light intensity is 60 mW / cm 2 , the wavelength λ of the light source is 254 nm, and hc / e is 1240×10 -9 J. After calculation, the finally obtained quantum yield is 0.8×10 −6 .

[0101] Specific examples are used in this article to elaborate on the principles and implementation methods of this application. The descriptions of the above examples are only used to help understand the method and its core idea of this application. At the same time, for those skilled in the art, based on the idea of this application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be construed as a limitation to this application.

Claims

1. A new type of thin-film quantum yield testing device, characterized in that, Comprising: A vacuum chamber, in which there are provided: an optical integrating sphere, a source meter, and an electrometer; The first side wall of the optical integrating sphere is fixed inside the vacuum chamber through an integrating sphere support. The second side wall of the optical integrating sphere is provided with an LED light source track, on which an LED light source is arranged, and the LED light source is slidably connected to the LED light source track; A sample support is arranged inside the third side wall of the optical integrating sphere. The sample support includes a connecting part and a sample placing part, and the connecting part is connected to the inside of the third side wall of the optical integrating sphere; A sample is placed on the sample placing part. The electrometer is arranged outside the optical integrating sphere and is electrically connected to the sample; the source meter is arranged outside the optical integrating sphere, and the source meter is electrically connected between the electrometer and the optical integrating sphere.

2. The novel thin-film quantum yield testing device according to claim 1, wherein The length of the LED light source track is 8 - 16 cm, and the incident angle range of the LED light source is -45° to 45°.

3. The novel thin-film quantum yield testing device according to claim 2, wherein The adjustable range of the wavelength of the LED light source is 250 nm to 275 nm; the adjustable range of the divergence angle of the LED light source is 45° to 135°.

4. The novel thin-film quantum yield testing device according to claim 3, characterized in that, The vacuum pressure of the vacuum chamber ≥ 10 -5 Pa, and the source meter applies a bias voltage and is powered by a battery.

5. The novel thin-film quantum yield testing device according to claim 4, wherein The test range of the source meter is -10 V to 10 V, and the resolution is 100 nV to 200 nV.

6. The novel thin film quantum yield testing device according to claim 5, characterized in that, The material of the sample holder is polyetheretherketone, and the resistance of the sample holder is ≥ 10 9 MΩ.

7. The novel thin-film quantum yield testing device according to claim 6, characterized in that, The diameter of the optical integrating sphere is 5 - 15 inches.

8. A novel thin-film quantum yield testing method for the novel thin-film quantum yield testing device according to any one of claims 1 to 7, characterized in that, Comprising: (1) Place the sample to be tested on the sample placing part of the sample support; (2) Detect the cleanliness and vacuum pressure inside the optical integrating sphere cavity; (3) Turn on the LED light source, set the optical parameters, and record the data; (4) Set the voltage parameters: adjust the magnitude of the bias voltage of the source meter to control the magnitude of the photocurrent, and record the data; (5) Calculate the work function and quantum yield of the sample.

9. The novel thin-film quantum yield testing method according to claim 8, characterized in that, Set the light source parameters, including: adjust the frequency of the LED light source to reach the threshold frequency of the photoelectric effect; adjust the divergence angle of the LED light source, adjust the LED light source track, change the incident angle of the LED light source, and adjust the power of the LED light source.

10. The novel thin film quantum yield testing method according to claim 9, characterized in that, In the step (5), calculate the work function and quantum yield of the sample, The calculation formula of the work function is as follows: Work function = incident photon energy - maximum initial kinetic energy of photoelectrons, wherein, the magnitude of the positive bias voltage required when the photocurrent decreases to zero corresponds to the maximum initial kinetic energy of the photoelectrons; The quantum yield is obtained according to the saturated photocurrent under the action of the bias voltage and the calibrated surface ultraviolet light intensity; The calculation formula of the quantum yield is as follows: ， Among them, η is the quantum yield, Jph is the saturation photocurrent in mA, P is the calibrated surface ultraviolet light intensity in mW / cm 2 , λ is the wavelength of the light source, h is Planck's constant, c is the speed of light, e is the electron charge, A is a constant, A = 1, with the unit J·cm / V.

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