Application of Cs4PbBr6, humidity sensor based on all-inorganic halide perovskite sensitive material and preparation method

Abstract

The application relates to the technical field of humidity sensors, in particular to application of Cs4PbBr6, a humidity sensor based on a full-inorganic halide perovskite sensitive material and a preparation method, the application adopts Cs4PbBr6 as a sensitive material of a humidity sensor, in working, Cs4PbBr6 in a high-resistance state is phase changed into CsPbBr3 in a low-resistance state under the induction of H2O, the response value of the full-inorganic halide perovskite to humidity is greatly improved, and the phase change process is reversible, so that the sensor based on the full-inorganic halide perovskite shows good response and recovery characteristics to humidity. The full-inorganic halide perovskite sensitive material Cs4PbBr6 has high sensitivity to humidity, is applied to a humidity sensor, and the manufactured humidity sensor is a high-performance sensor, can realize rapid response in a full-humidity range, and can be applied to practical scene applications such as breath detection and fingertip contact.

Description

Technical Field

[0001] This invention relates to the technical field of humidity sensors, specifically to the application of Cs4PbBr6, a humidity sensor based on an all-inorganic halide perovskite sensitive material, and its preparation method. Background Technology

[0002] Humidity sensors play a crucial role in fields such as human respiratory monitoring, agricultural and biological monitoring, industrial production monitoring, and non-contact switches because they can convert air humidity information into electrical signals in real time. To realize the large-scale application of humidity-sensitive materials in future intelligent and integrated devices, it is necessary to consider the water molecule adsorption-desorption properties, wide-range and high-sensitivity response characteristics of the materials to meet the needs of environmental detection and health monitoring under specific conditions.

[0003] Halide perovskite materials have become a potential choice for sensitive materials due to their advantages such as high room-temperature carrier migration rates, sensitive surface properties, directly tunable band gaps, simple fabrication, and cost-effectiveness. The valence state and conductivity of ions on the material surface change with environmental factors such as temperature, humidity, atmosphere, and light. These characteristics perfectly match the detection requirements of sensors, making halide perovskite materials a promising candidate for the field of humidity sensing.

[0004] However, traditional organic-inorganic hybrid halide perovskites suffer from poor water, thermal, and chemical stability, limiting their application in humidity sensors. Therefore, the development of highly stable humidity sensors based on all-inorganic halide perovskites is urgently needed. Summary of the Invention

[0005] One of the objectives of this invention is to provide an application of Cs4PbBr6, using it as a Cs4PbBr6 sensitive material in a humidity sensor.

[0006] The second objective of this invention is to provide a humidity sensor based on an all-inorganic halide perovskite sensitive material, which can achieve rapid response and recovery across the entire humidity range and has excellent stability.

[0007] The third objective of this invention is to provide a method for preparing a humidity sensor based on an all-inorganic halide perovskite sensitive material, which is simple to prepare and easy to adjust.

[0008] One of the solutions adopted to achieve the objective of this invention is: an application of Cs4PbBr6, in which Cs4PbBr6 is used as a sensitive material in a humidity sensor.

[0009] The second objective of this invention is achieved by a humidity sensor based on an all-inorganic halide perovskite sensitive material, wherein the humidity sensor includes interdigitated electrodes and a sensitive material Cs4PbBr6 coated on the surface of the interdigitated electrodes.

[0010] Preferably, the metal layer of the interdigitated electrode is gold or silver; the thickness of the metal layer is 30–100 nm.

[0011] Preferably, the preparation method of the sensitive material Cs4PbBr6 includes the following steps:

[0012] A1. Under heating conditions, cesium acetate is dissolved in oleic acid to obtain a cesium source solution;

[0013] A2. Under heating and an inert atmosphere, lead bromide is dissolved in an octadecene solution to obtain a lead bromide solution;

[0014] A3. Oleic acid and oleylamine are added to the lead bromide solution under heating and an inert atmosphere to obtain a complex solution of the metal salt;

[0015] A4. Under heating and an inert atmosphere, a cesium source solution is added to the complexation solution of the metal salt, and the sensitive material based on the all-inorganic halide perovskite is obtained through a hot injection reaction.

[0016] Preferably, in step A1, the heating temperature is 50-200℃, and the molar ratio of cesium acetate to the volume of oleic acid is 0.1-2 mmol:1 ml.

[0017] Preferably, in step A2, the heating temperature is 100-150℃, and the molar ratio of lead bromide to octadecene is 0.4 mmol: 10-30 ml.

[0018] Preferably, in step A3, the heating temperature is 100-150℃, and the volume ratio of lead bromide solution, oleic acid, and oleylamine is 20:1-5:1-5.

[0019] Preferably, in step A4, the heating temperature is 100-200℃, and the volume ratio of the cesium source solution to the metal salt complex solution is 1:10-25.

[0020] This invention prepares all-inorganic halide perovskites via a hot-injection method, exhibiting better stability compared to organic-inorganic hybrid perovskites, with smaller average size, smaller standard deviation of size distribution, and better reproducibility of the material synthesis process. The surface ligands used in the preparation process enhance the material's stability, enabling the humidity sensor to operate for extended periods. This invention enables the controllable preparation of all-inorganic halide perovskites, featuring low cost, simple method, and good reproducibility.

[0021] The solution adopted to achieve the third objective of this invention is: a method for preparing a humidity sensor based on an all-inorganic halide perovskite sensitive material, comprising the following steps:

[0022] B1. Fabrication of interdigitated electrodes;

[0023] B2. Coat the surface of the interdigital electrode with the sensitive material evenly;

[0024] B3. The sensitive material covering the surface of the interdigital electrodes is heat-treated at a certain temperature, and then assembled to obtain the humidity sensor.

[0025] Preferably, in step B2, the sensitive material is uniformly coated onto the surface of the interdigital electrode using a spin coating method. Specifically, 10-100 μl of the sensitive material is dropped onto the surface of the interdigital electrode and spin-coated at a speed of 1000-4000 r / min for 10-60 s.

[0026] Furthermore, 30-60 μl of sensitive material is dropped onto the surface of the interdigital electrode and spin-coated at a speed of 1500-4000 r / min for 30-60 s.

[0027] This invention prepares a humidity sensor based on an all-inorganic halide perovskite using a spin-coating method. The thickness of the sensitive material film can be precisely controlled by the concentration of the sensitive material, the spin-coating speed, and the spin-coating time, thereby obtaining a highly repeatable sensitive material film and a humidity sensor based on an all-inorganic halide perovskite, which shows great potential in the mass production of sensors.

[0028] Preferably, in step B3, the heat treatment temperature is 30-120℃ and the heat treatment time is 10-120min.

[0029] Furthermore, the heat treatment temperature is 60-80℃, and the heat treatment time is 30-60 minutes.

[0030] The present invention has the following advantages and beneficial effects:

[0031] This invention uses Cs4PbBr6 as the sensitive material of a humidity sensor. During operation, the high-resistivity Cs4PbBr6 undergoes a phase transformation into the low-resistivity CsPbBr3 under the induction of H2O, which greatly improves the response value of the all-inorganic halide perovskite to humidity. Moreover, this phase transformation process is reversible. Therefore, the sensor based on this all-inorganic halide perovskite exhibits good response and recovery characteristics to humidity.

[0032] The all-inorganic halide perovskite sensitive material Cs4PbBr6 of this invention has high sensitivity to humidity. When applied to humidity sensors, the humidity sensor manufactured is a high-performance sensor that can achieve rapid response across the entire humidity range and can be used in practical applications such as breath detection and fingertip contact.

[0033] The preparation method of the present invention is simple, highly controllable, and easy to achieve mass production. Attached Figure Description

[0034] Figure 1 The XRD pattern of Cs4PbBr6 prepared in Example 1;

[0035] Figure 2 The resistance change of the Cs4PbBr6 humidity sensor prepared in Example 2 in 11%-98%RH;

[0036] Figure 3 The resistance change of the Cs4PbBr6 humidity sensor prepared in Example 3 after 8 cycles in 11% and 98% RH.

[0037] Figure 4 The results show the resistance values ​​of the Cs4PbBr6 humidity sensor prepared in Example 4 as continuously changing from 11%RH to 98%RH and back to 11%RH. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0039] This invention provides a method for preparing an all-inorganic halide perovskite material, comprising the following steps:

[0040] Step A1. Under heating conditions of 50-200℃, cesium acetate is dissolved in oleic acid at a ratio of 0.1-2 mmol: 1 ml, and heated for 30-60 min to obtain a cesium source solution.

[0041] Step A2. Under an inert atmosphere and at a temperature of 100-150℃, dissolve lead bromide in an octadecene solution at a ratio of 0.4 mmol to 10-30 ml, and heat for 10-30 minutes to obtain a lead bromide solution.

[0042] Step A3. Under heating at 100-150℃ and in an inert atmosphere, add oleic acid and oleylamine to the lead bromide solution at a ratio of 20ml:1-5ml:1-5ml, and heat for 20-60 minutes to obtain a complex solution of the metal salt.

[0043] Step A4. Under heating at 100-200℃ and in an inert atmosphere, add the cesium source solution to the metal salt complex solution at a ratio of 1ml:10-25ml, and obtain the all-inorganic halide perovskite sensitive material through a hot injection reaction.

[0044] The product after the hot injection reaction was washed with tert-butanol.

[0045] This invention provides a highly sensitive humidity sensor based on a thin-film sensitive material, comprising a substrate and interdigitated electrodes based on an all-inorganic halide perovskite sensitive material; wherein: the all-inorganic halide perovskite is prepared by a hot-injection method; the interdigitated electrodes are manufactured on the surface of the substrate by a mask evaporation technique, that is, the humidity sensor of this invention has a layered structure, consisting of a substrate layer, interdigitated electrodes and an all-inorganic halide perovskite thin film layer from bottom to top.

[0046] The method for preparing the humidity sensor of the present invention includes the following steps:

[0047] Step B1. Prepare interdigitated electrodes using the metal mask method. Place the substrate in a vapor deposition apparatus, cover it with a metal mask containing interdigitated electrodes with different spacings of 100-150 μm, and then vapor deposit 30-100 nm of Au or Ag.

[0048] In step B1 above, the metal mask is a stainless steel plate with laser-engraved electrode patterns, and the substrate is glass. The selected glass substrate undergoes pretreatment. First, it is cleaned in deionized water and ethanol at an ultrasonic power of 1000-2000W for 15-20 minutes respectively. Then, the surface of the glass substrate is purged with an inert gas, either argon or nitrogen, for 1-5 minutes to remove surface liquid. Finally, the surface is treated with oxygen plasma.

[0049] Step B2. Using spin coating, drop 30-60 μl of sensitive material onto the surface of the interdigital electrode and spin coat at a speed of 1500-4000 r / min for 10-60 s.

[0050] Step B3. The sensitive material covering the surface of the interdigital electrodes is heat-treated on a heating stage at a constant temperature of 60-80℃ for 30-60 minutes to obtain the humidity sensor.

[0051] The humidity sensor prepared in this invention uses a humidity-sensitive all-inorganic halide perovskite sensitive material, which can achieve high resistance response in the range of 11%-98% relative humidity and has good stability.

[0052] The present invention will be further described in detail below through specific embodiments.

[0053] Example 1

[0054] The Cs4PbBr6 preparation method provided in Example 1 includes the following steps:

[0055] Step 1. Add 10 mmol of cesium acetate to 10 ml of oleic acid and heat at 120 °C for 30 min to obtain a cesium source solution;

[0056] Step 2. Under an Ar atmosphere, dissolve 0.4 mmol of lead bromide in 25 ml of octadecene solution and heat at 120 °C for 20 min to obtain lead bromide solution;

[0057] Step 3. Under an Ar atmosphere, add 2 ml of oleic acid and 2 ml of oleylamine to the above lead bromide solution, and heat at 120°C for 30 min to obtain a complex solution of the metal salt;

[0058] Step 4. Under an Ar atmosphere, heat the complex solution of the metal salt at 145°C for 10 min, add 1 ml of cesium source solution, and obtain the all-inorganic halide perovskite Cs4PbBr6.

[0059] Comparative Example 1

[0060] Set the heating temperature in step 4 to 80°C, and keep other conditions the same as in Example 1.

[0061] The results showed that the prepared Cs4PbBr6 contained the CsBr impurity phase. Therefore, lower temperatures are not conducive to the synthesis of Cs4PbBr6, and the preferred temperature for this invention is 100-200℃.

[0062] Comparative Example 2

[0063] Change the amount of cesium source solution in step 4 to 0.1 ml, and keep other conditions the same as in Example 1.

[0064] The results showed that CsPbBr3 was prepared instead of Cs4PbBr6. Therefore, too little cesium source solution is not conducive to the synthesis of Cs4PbBr6. The preferred volume ratio of cesium source solution to metal salt complex solution in this invention is 1:10-25.

[0065] Example 2

[0066] This embodiment provides a method for fabricating a humidity sensor based on the all-inorganic halide perovskite sensitive material Cs4PbBr6, including the following steps:

[0067] Step 1. Place the glass substrate in the vapor deposition apparatus, cover it with a metal mask with interdigitated electrodes with a spacing of 100 μm, and then vapor deposit 30 nm of Au.

[0068] Step 2. Drop 30 μl of the sensitive material onto the surface of the interdigital electrode and spin coat it at 1500 r / min for 10 s;

[0069] Step 3. The sensitive material covering the surface of the interdigital electrodes is heat-treated on a heating stage at a constant temperature of 60°C for 30 minutes to obtain the humidity sensor.

[0070] Example 3

[0071] This embodiment provides a method for fabricating a humidity sensor based on the all-inorganic halide perovskite sensitive material Cs4PbBr6, including the following steps:

[0072] Step 1. Place the glass substrate in the vapor deposition apparatus, cover it with a metal mask with interdigitated electrodes with a spacing of 100 μm, and then vapor deposit 60 nm of Au.

[0073] Step 2. Drop 40 μl of the sensitive material onto the surface of the interdigital electrode and spin coat it at 2000 r / min for 30 s;

[0074] Step 3. The sensitive material covering the surface of the interdigital electrodes is heat-treated on a heating stage at a constant temperature of 70°C for 40 minutes to obtain the humidity sensor.

[0075] Example 4

[0076] This embodiment provides a method for fabricating a humidity sensor based on the all-inorganic halide perovskite sensitive material Cs4PbBr6, including the following steps:

[0077] Step 1. Place the glass substrate in the vapor deposition apparatus, cover it with a metal mask with interdigitated electrodes with a spacing of 150 μm, and then vapor deposit 100 nm Au.

[0078] Step 2. Drop 60 μl of the sensitive material onto the surface of the interdigitated electrode and spin coat it at 4000 r / min for 60 s;

[0079] Step 3. The sensitive material covering the surface of the interdigital electrodes is heat-treated on a heating stage at a constant temperature of 80°C for 60 minutes to obtain the humidity sensor.

[0080] Test Analysis

[0081] The XRD pattern of Cs4PbBr6 prepared in Example 1 of this invention is shown in the figure. Figure 1The results showed that the XRD pattern of the prepared Cs4PbBr6 was in high agreement with the standard PDF card of Cs4PbBr6, indicating that pure phase Cs4PbBr6 was prepared.

[0082] The resistance change of the Cs4PbBr6 humidity sensor prepared in Example 2 of this invention in 11%-98% RH is shown in the figure. Figure 2 The results show that the prepared Cs4PbBr6 humidity sensor has a response value of 40 in the range of 11%-98% RH, and the maximum hysteresis occurs at 84% RH, which is only 0.19%. This humidity sensor has the characteristics of high response and low hysteresis.

[0083] The resistance change of the Cs4PbBr6 humidity sensor prepared in Example 3 of this invention after 8 cycles in 11% and 98% RH environments is shown in the figure. Figure 3 The results show that the prepared Cs4PbBr6 humidity sensor maintains a stable resistance response even after undergoing eight consecutive cycles from low humidity to high humidity, demonstrating the high stability of the prepared Cs4PbBr6 humidity sensor.

[0084] The Cs4PbBr6 humidity sensor prepared in Example 4 of this invention shows a continuous change in resistance value from 11% RH to 98% RH and back to 11% RH. Figure 4 The results show that the prepared Cs4PbBr6 humidity sensor has a response time of 20 s and a recovery time of 20 s, indicating that the prepared Cs4PbBr6 humidity sensor has the ability to respond and recover quickly.

[0085] This invention provides a highly sensitive humidity sensor based on an all-inorganic halide perovskite and its fabrication method. The method uses an all-inorganic halide perovskite as the humidity-sensitive material and involves a thermal injection synthesis method. The humidity sensor is fabricated on a glass substrate using a mask evaporation process, where interdigitated electrodes of different sizes are prepared on the glass substrate surface. The all-inorganic halide perovskite obtained by this invention exhibits high response values ​​and fast response / recovery performance due to the phase transition of the Cs4PbBr6 thin film induced by H2O, as well as the film's uniformity and high specific surface area. This sensor can realize functions such as monitoring human respiration and detecting humidity changes when a fingertip is near, showing great promise for electronic device and medical monitoring applications.

[0086] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A humidity sensor based on an all-inorganic halide perovskite sensitive material, characterized in that: The humidity sensor includes interdigitated electrodes and a sensitive material Cs4PbBr6 coated on the surface of the interdigitated electrodes. During operation, the high-resistivity Cs4PbBr6 undergoes a phase transition to a low-resistivity CsPbBr3 under the induction of H2O. This phase transition process is reversible and can achieve a high resistance response in the range of 11%-98% relative humidity.

2. The humidity sensor based on an all-inorganic halide perovskite sensitive material as described in claim 1, characterized in that: The metal layer of the interdigitated electrode is gold or silver; the thickness of the metal layer is 30~100 nm.

3. The humidity sensor based on an all-inorganic halide perovskite sensitive material as described in claim 1, characterized in that: The preparation method of the sensitive material Cs4PbBr6 includes the following steps: A1. Under heating conditions, cesium acetate is dissolved in oleic acid to obtain a cesium source solution; A2. Under heating and an inert atmosphere, lead bromide is dissolved in an octadecene solution to obtain a lead bromide solution; A3. Oleic acid and oleylamine are added to the lead bromide solution under heating and an inert atmosphere to obtain a complex solution of the metal salt; A4. Under heating and an inert atmosphere, a cesium source solution is added to the complexation solution of the metal salt, and the sensitive material based on the all-inorganic halide perovskite is obtained through a hot injection reaction.

4. The humidity sensor based on an all-inorganic halide perovskite sensitive material as described in claim 3, characterized in that: In step A1, the heating temperature is 50-200℃, and the molar ratio of cesium acetate to the volume of oleic acid is 0.1-2 mmol:1 ml.

5. The humidity sensor based on an all-inorganic halide perovskite sensitive material as described in claim 3, characterized in that: In step A2, the heating temperature is 100-150℃, and the molar ratio of lead bromide to octadecene is 0.4 mmol: 10-30 ml.

6. The humidity sensor based on an all-inorganic halide perovskite sensitive material as described in claim 3, characterized in that: In step A3, the heating temperature is 100-150℃, and the volume ratio of lead bromide solution, oleic acid, and oleylamine is 20:1-5:1-5; in step A4, the heating temperature is 100-200℃, and the volume ratio of cesium source solution to metal salt complex solution is 1:10-25.

7. A method for preparing a humidity sensor based on an all-inorganic halide perovskite sensitive material as described in any one of claims 1-6, characterized in that, Includes the following steps: B1. Fabrication of interdigitated electrodes; B2. Coat the surface of the interdigital electrode with the sensitive material evenly; B3. The sensitive material covering the surface of the interdigital electrodes is heat-treated at a certain temperature, and then assembled to obtain the humidity sensor.

8. The method for preparing a humidity sensor based on an all-inorganic halide perovskite sensitive material as described in claim 7, characterized in that: In step B2, the sensitive material is uniformly coated onto the surface of the interdigital electrode using a spin coating method. Specifically, 10-100 μl of the sensitive material is dropped onto the surface of the interdigital electrode and spin-coated at a speed of 1000-4000 r / min for 10-60 s.

9. The method for preparing a humidity sensor based on an all-inorganic halide perovskite sensitive material as described in claim 7, characterized in that: In step B3, the heat treatment temperature is 30-120℃ and the heat treatment time is 10-120min.

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