Application of Z907 dye in enhancing photoelectric property of Cs2AgBiBr6 semiconductor film, preparation method of Cs2AgBiBr6 semiconductor film and self-energized detector

Abstract

The invention relates to the field of lead-free perovskite semiconductor materials and photoelectricity, in particular to application of Z907 dye in enhancing the photoelectric property of a Cs2AgBiBr6 semiconductor film, a preparation method of the Cs2AgBiBr6 semiconductor film and a self-powered detector. The preparation method of the Cs2AgBiBr6 semiconductor film comprises the following steps: S1, cleaning an FTO (Fluorine-doped Tin Oxide) conductive glass substrate; s2, dissolving CsBr, AgBr and BiBr3 in dimethyl sulfoxide together, so as to form a Cs2AgBiBr6 precursor solution; s3, adding a Z907 dye into the Cs2AgBiBr6 precursor solution obtained in the step S2, and then stirring at 110 DEG C for 1 hour; s4, cooling the FTO conductive glass substrate and the precursor solution in a glove box to room temperature, filtering, preheating to 75 DEG C, and keeping for 10 minutes; and S5, spin-coating the preheated precursor solution on an FTO conductive glass substrate, and then immediately placing the FTO conductive glass substrate on a heating plate at 250 DEG C for annealing for 5 minutes. Compared with a self-powered light detector formed by an undoped Cs2AgBiBr6 semiconductor film, the light current response and the detection rate of a device prepared by using the Cs2AgBiBr6 semiconductor film doped with the dye molecule Z907 with the concentration of 1 mg / mL are enhanced by 50%.

Description

Technical Field

[0001] The present invention relates to the field of lead-free perovskite semiconductor materials and optoelectronics, and particularly relates to a Cs2AgBiBr6 semiconductor thin film and a corresponding self-powered photodetector. Background Art

[0002] Due to their excellent optoelectronic properties, perovskite semiconductor materials have broad application prospects in the fields of photodetection, photovoltaic conversion, and photocatalysis. Among them, lead-based perovskites have been widely used in high-performance photodetectors due to their high light absorption coefficient, long carrier lifetime, and excellent charge transport properties. However, the toxicity of lead and the instability of its compounds severely limit the long-term stability and large-scale application of the devices (Advanced Functional Materials, 2025, 35, 2412389; Advanced Energy Materials, 2023, 13, 2204144). Therefore, the research on lead-free perovskite materials has become an important direction in the field of optoelectronics in recent years.

[0003] As a lead-free perovskite material with a double perovskite structure, Cs2AgBiBr6 has received extensive attention due to its good environmental stability and low toxicity (Advanced Functional Materials, 2021, 31, 2105898). This material has a suitable bandgap, high crystallinity, and excellent thermal stability, making it a potential candidate for the next generation of photodetectors. However, the large number of defect states in Cs2AgBiBr6 leads to severe carrier recombination, which limits its application in photodetection (Advanced Science, 2018, 5, 1700759). Therefore, how to improve the separation and transport efficiency of photo-generated carriers in Cs2AgBiBr6 has become the key issue for enhancing its photodetection performance.

[0004] In recent years, the metal ion doping technology has shown great potential in the modification of semiconductor optoelectronic materials. By doping Na into Cs2AgBiBr6 nanocrystal powder + doping, the parity-forbidden transition induced by its inversion symmetry is disrupted, causing the parity of the wave function of self-trapped excitons at Ag atoms to change, thereby promoting the occurrence of radiative transitions (Advanced Optical Materials, 2023, 11, 2202745). When Rb + is incorporated into Cs2AgBiBr6 to form (Cs 1-x Rb x)When doped with 2AgBiBr6, the long - wave absorption of the material is enhanced, and at the same time, the density of defect states decreases, while the lattice structure remains unchanged (Organic Electronics, 2019, 74, 204). However, when doping metal ions (such as Sb 3+ 、In 3+ etc.), if the radius is quite different from that of Ag + or Bi 3+ , it will lead to lattice distortion, destroy the cubic structure of double perovskite (such as forming amorphous phase or defect clusters), and even induce phase separation, for example, generating impurity phases such as Cs3Bi2Br9, (Chemistry of Materials, 2020, 32, 8129). Secondly, if the doping is not precisely controlled (such as too high concentration or uneven distribution), it may introduce more deep - level defects (such as interstitial atoms, vacancies), which become carrier recombination centers and reduce the carrier lifetime (Advanced Functional Materials, 2020, 30, 2005521).

[0005] It has been reported that doping the organic perovskite CH3NH3PbI3 thin film with the organic dye molecule N719 can improve its moisture - resistance stability, but the improvement of the optoelectronic properties of this organic perovskite by doping with the organic dye molecule N719 is very small (Solar RRL, 2019, 3, 1900345). The full Chinese name of the organic dye molecule N719 is: bis(tetrabutylammonium) cis - bis(isothiocyanato) bis(2,2'-bipyridine - 4,4'-dicarboxylate) ruthenium(II)]. Summary of the Invention

[0006] One of the purposes of the present invention is to provide an application of Z907 dye in enhancing the optoelectronic properties of Cs2AgBiBr6 inorganic perovskite semiconductor thin film. By introducing the organic dye molecule Z907 into the Cs2AgBiBr6 inorganic perovskite semiconductor thin film, the photocurrent response intensity of the Cs2AgBiBr6 semiconductor thin film is improved.

[0007] The full name of Z907 dye is: cis - bis(isothiocyanato) - bis(2,2'-bipyridine - 4,4'-dicarboxylate)(4,4'-dinonyl - 2,2'-bipyridine) ruthenium(II)].

[0008] As an improvement, the Z907 dye is doped in the Cs2AgBiBr6 semiconductor thin film. The doping method is: doping the Z907 dye into the precursor solution for preparing the Cs2AgBiBr6 semiconductor thin film, and adding 0.5 - 2 mg of Z907 dye into every 1 mL of the Cs2AgBiBr6 precursor solution.

[0009] The second object of the present invention is to provide a method for preparing a Cs2AgBiBr6 semiconductor thin film, comprising the following steps:

[0010] Step S1: Clean the FTO conductive glass substrate;

[0011] Step S2: Dissolve CsBr, AgBr, and BiBr3 together in dimethyl sulfoxide to form a Cs2AgBiBr6 precursor solution;

[0012] Step S3: Add Z907 dye to the Cs2AgBiBr6 precursor solution obtained in Step S2. Add 0.5 - 2 mg of Z907 dye to every 1 mL of the Cs2AgBiBr6 precursor solution, and then stir on a heating stage in a nitrogen glove box at 110 °C for 1 hour to obtain a Z907-doped Cs2AgBiBr6 precursor solution of dye molecules;

[0013] Step S4: Cool the FTO conductive glass substrate obtained in Step S1 and the precursor solution obtained in Step S3 to room temperature in the glove box and filter. Then preheat on a glove box heating plate to 75 °C and hold for 10 minutes;

[0014] Step S5: Spin-coat the preheated precursor solution in Step S4 on the preheated FTO conductive glass substrate in the glove box at a rotation speed of 4000 revolutions per minute for 45 seconds, and then immediately place it on a 250 °C heating plate for annealing for 5 minutes.

[0015] As an improvement, in Step S1, the FTO conductive glass substrate is cleaned with acetone and isopropanol in ultrasonic waves, then rinsed with deionized water and ethanol, and cleaned with ultraviolet ozone for 30 minutes.

[0016] As an improvement, in Step S2, 1.1 mmol of CsBr, 0.55 mmol of AgBr, and 0.55 mmol of BiBr3 are dissolved together in 1 mL of dimethyl sulfoxide to form 1 mL of Cs2AgBiBr6 precursor solution.

[0017] As an improvement, in Step S3, 1 mg of Z907 dye is added to every 1 mL of the Cs2AgBiBr6 precursor solution.

[0018] The third object of the present application is to provide a self-powered detector with a relatively high photocurrent response intensity.

[0019] This self-powered photodetector is composed of a glass substrate, an FTO layer, a TiO2 electron transport layer, a Z907-doped Cs2AgBiBr6 thin film of dye molecules, and a carbon electrode.

[0020] The beneficial effects of the present invention are:

[0021] (1) Using an appropriate amount of Z907 dye molecules can affect the nucleation and growth kinetics of the precursor, making the crystallization process slower and more orderly. The atomic force microscopy characterization results show that this method is beneficial for the formation of larger grains in the Cs2AgBiBr6 semiconductor thin film, and the surface photovoltage spectrum shows that doping with an appropriate amount of Z907 dye molecules can improve the separation of photo-generated carriers in the Cs2AgBiBr6 semiconductor thin film.

[0022] (2) Compared with the self-powered photodetector composed of the undoped Cs2AgBiBr6 semiconductor thin film, for the device prepared with the Cs2AgBiBr6 semiconductor thin film doped with 1 mg / mL dye molecule Z907, both its photocurrent response and detectivity are enhanced by about 50%.

[0023] (3) The preparation method has simple process, is environmentally friendly, and has low requirements for equipment, making it suitable for large-scale applications and having great application potential in the fields of photoelectric detection and low-cost solar cells, etc.

[0024] (4) By adjusting the content of the dye molecule Z907 doped in the Cs2AgBiBr6 precursor solution, the different photocurrent responses of the self-powered photodetector can be adjusted. Description of the Drawings

[0025] Figure 1 (a) is the atomic force microscopy morphology diagram of an intrinsically undoped Cs2AgBiBr6 semiconductor thin film obtained in Example 1 of the present invention; Figure 1 (b) is the surface photovoltage spectrum of an intrinsically undoped Cs2AgBiBr6 semiconductor thin film obtained in Example 1 of the present invention.

[0026] Figure 2 (a) is the atomic force microscopy morphology diagram of a Cs2AgBiBr6 semiconductor thin film doped with 0.5 mg / mL dye molecule Z907 obtained in Example 2 of the present invention; Figure 2 (b) is the surface photovoltage spectrum of a Cs2AgBiBr6 semiconductor thin film doped with 0.5 mg / mL dye molecule Z907 obtained in Example 2 of the present invention. Figure 3 (a) is the atomic force microscopy morphology diagram of a Cs2AgBiBr6 semiconductor thin film doped with 1 mg / mL dye molecule Z907 obtained in Example 3 of the present invention; Figure 3 (b) is the surface photovoltage spectrum of a Cs2AgBiBr6 semiconductor thin film doped with 1 mg / mL dye molecule Z907 obtained in Example 3 of the present invention.

[0027] Figure 4(a) is the atomic force microscope topography of a 2 mg / mL dye molecule Z907-doped Cs2AgBiBr6 semiconductor thin film obtained in Example 4 of the present invention; Figure 4 (b) is the surface photovoltage spectrum of a 1 mg / mL dye molecule Z907-doped Cs2AgBiBr6 semiconductor thin film obtained in Example 4 of the present invention.

[0028] Figure 5 are the (a) photocurrent-time response curves, (b) responsivity curves, and (c) detectivity curves of the self-powered photodetectors obtained in Examples 1-4 of the present invention under different LED white light intensities. Detailed implementation manners

[0029] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0030] Example 1: An intrinsically undoped Cs2AgBiBr6 semiconductor thin film.

[0031] (1) The FTO conductive glass substrate is cleaned with acetone and isopropanol in ultrasonic waves, rinsed with deionized water and ethanol, and cleaned with ultraviolet ozone for 30 minutes;

[0032] (2) 1.1 mmol CsBr, 0.55 mmol AgBr, and 0.55 mmol BiBr3 are dissolved in 1 mL of dimethyl sulfoxide to form a 1 mL Cs2AgBiBr6 precursor solution;

[0033] (3) The obtained Cs2AgBiBr6 precursor solution is stirred on a heating table in a nitrogen glove box at 110 °C for 1 hour;

[0034] (4) The FTO conductive glass substrate obtained in step (1) and the precursor solution obtained in step (3) are cooled to room temperature and filtered in the glove box, and then preheated to 75 °C on a glove box heating plate and held for 10 minutes;

[0035] (5) The preheated precursor solution in step (4) is spin-coated on the preheated FTO conductive glass substrate in step (4) at a speed of 4000 revolutions per minute for 45 seconds, and then immediately placed on a 250 °C heating plate for annealing for 5 minutes.

[0036] (6) Characterization of the product: As Figure 1As shown in [[a]], the obtained Cs2AgBiBr6 semiconductor thin film without any doping has a grain size distribution ranging from 50 to 80 nm. As Figure 1 As shown in [[b]], the maximum value of SPV of the obtained Cs2AgBiBr6 semiconductor thin film without any doping is 180 μV.

[0037] Example 2: Cs2AgBiBr6 semiconductor thin film doped with 0.5 mg / mL dye molecule Z907.

[0038] (1) The FTO conductive glass substrate was cleaned with acetone and isopropanol in ultrasonic waves, rinsed with deionized water and ethanol, and cleaned with ultraviolet ozone for 30 minutes;

[0039] (2) 1.1 mmol CsBr, 0.55 mmol AgBr, and 0.55 mmol BiBr3 were dissolved in 1 mL of dimethyl sulfoxide to form 1 mL of Cs2AgBiBr6 precursor solution;

[0040] (3) 0.5 mg of dye molecule Z907 was added to the obtained precursor solution. The 1 mL of Cs2AgBiBr6 precursor solution obtained in step (2) was stirred on a heating table at 110 °C for 1 hour in a nitrogen glove box to obtain a Cs2AgBiBr6 precursor solution doped with dye molecule Z907;

[0041] (4) The FTO conductive glass substrate obtained in step (1) and the precursor solution obtained in step (3) were cooled and filtered in the glove box, and then preheated to 75 °C on a glove box heating plate and maintained for 10 minutes;

[0042] (5) In the glove box, the precursor solution preheated in step (4) was spin-coated on the FTO conductive glass substrate preheated in step (4) at a speed of 4000 revolutions per minute for 45 seconds, and then immediately placed on a 250 °C heating plate for annealing for 5 minutes.

[0043] (6) Characterization of the product: As Figure 2 As shown in [[a]], the obtained Cs2AgBiBr6 semiconductor thin film doped with 0.5 mg / mL dye molecule Z907 has a grain size distribution ranging from 100 to 150 nm. As Figure 2 As shown in [[b]], the maximum value of SPV of the obtained Cs2AgBiBr6 semiconductor thin film doped with 0.5 mg / mL dye molecule Z907 is 250 μV.

[0044] Example 3: Cs2AgBiBr6 semiconductor thin film doped with 1 mg / mL dye molecule Z907.

[0045] (1) The FTO conductive glass substrate was cleaned with acetone and isopropanol in ultrasonic waves, rinsed with deionized water and ethanol, and cleaned with ultraviolet ozone for 30 minutes;

[0046] (2) Dissolve 1.1 mmol of CsBr, 0.55 mmol of AgBr, and 0.55 mmol of BiBr3 in 1 mL of dimethyl sulfoxide to form 1 mL of a Cs2AgBiBr6 precursor solution;

[0047] (3) Add 1 mg of dye molecule Z907 to the obtained precursor solution. The 1 mL of Cs2AgBiBr6 precursor solution obtained in step (2) is stirred on a heating stage at 110 °C for 1 hour in a nitrogen glove box to obtain a dye molecule Z907-doped Cs2AgBiBr6 precursor solution;

[0048] (4) Cool and filter the FTO conductive glass substrate obtained in step (1) and the precursor solution obtained in step (3) in the glove box, and then preheat it to 75 °C on a glove box hot plate and hold for 10 minutes;

[0049] (5) Spin-coat the preheated precursor solution in step (4) onto the preheated FTO conductive glass substrate in the glove box at a rotation speed of 4000 revolutions per minute for 45 seconds, and then immediately place it on a 250 °C hot plate for annealing for 5 minutes.

[0050] (6) Characterization of the product: As Figure 3 shown, for the obtained 1 mg / mL dye molecule Z907-doped Cs2AgBiBr6 semiconductor thin film, the grain size distribution is in the range of 150 - 200 nm. As Figure 3 shown in b, the maximum value of SPV of the obtained 1 mg / mL dye molecule Z907-doped Cs2AgBiBr6 semiconductor thin film is 700 μV.

[0051] Example 4: 2 mg / mL dye molecule Z907-doped Cs2AgBiBr6 semiconductor thin film.

[0052] (1) The FTO conductive glass substrate is cleaned with acetone and isopropanol in ultrasonic waves, rinsed with deionized water and ethanol, and cleaned with ultraviolet ozone for 30 minutes;

[0053] (2) Dissolve 1.1 mmol of CsBr, 0.55 mmol of AgBr, and 0.55 mmol of BiBr3 in 1 mL of dimethyl sulfoxide to form 1 mL of a Cs2AgBiBr6 precursor solution;

[0054] (3) Add 2 mg of dye molecule Z907 to the obtained precursor solution. The 1 mL of Cs2AgBiBr6 precursor solution obtained in step (2) is stirred on a heating stage at 110 °C for 1 hour in a nitrogen glove box to obtain a dye molecule Z907-doped Cs2AgBiBr6 precursor solution;

[0055] (4) Cool and filter the FTO conductive glass substrate obtained in step (1) and the precursor solution obtained in step (3) in a glove box, and then preheat it to 75 °C on a glove box heating plate and hold for 10 minutes;

[0056] (5) Spin-coat the precursor solution preheated in step (4) on the FTO conductive glass substrate preheated in step (4) in a glove box at a speed of 4000 revolutions per minute for 45 seconds, and then immediately anneal it on a 250 °C heating plate for 5 minutes.

[0057] (6) Characterization of the product: As Figure 4 shown in a, for the obtained Cs2AgBiBr6 semiconductor thin film doped with 2 mg / mL dye molecule Z907, the thin film becomes very rough and is composed of many small grains. This is because when the dye concentration is too high, they will form an overly thick covering layer at the crystal nuclei and grain boundaries, thus hindering the further diffusion of ions and the merging of grains, resulting in a smaller grain size. As Figure 4 shown in b, the SPV of the obtained Cs2AgBiBr6 semiconductor thin film doped with 2 mg / mL dye molecule Z907 is significantly weakened, and its maximum value is 75 μV. The excessive doping of Z907 on the surface is not conducive to charge separation.

[0058] Example 5: Use the Cs2AgBiBr6 products in Examples 1-4 to prepare a self-powered photodetector and conduct photoelectric response characterization and summary comparison.

[0059] 1. The preparation steps of the self-powered photodetector are as follows:

[0060] (1) Dissolve 10 mg of the organic hole transport layer material poly(3-hexylthiophene-2,5-diyl) in chlorobenzene solvent;

[0061] (2) Place the Cs2AgBiBr6 samples in Examples 1-4 in a nitrogen glove box, spin-coat the above poly(3-hexylthiophene-2,5-diyl) solution onto the Cs2AgBiBr6 samples at a speed of 1500 rpm, and then anneal it on a heating stage at 150 °C for 10 minutes.

[0062] (3) Finally, scrape the carbon paste on the surface of poly(3-hexylthiophene-2,5-diyl) and dry it on a heating stage at 150 °C for 1 hour to make a carbon electrode. The obtained structure is as Figure 1 shown.

[0063] 2. Photoelectric response characterization and summary comparison

[0064] The characterization results of the photocurrent-time response performance, responsivity, and detectivity curves of the Cs2AgBiBr6 self-powered photodetector are shown in Figure 6. The results show that the self-powered photodetectors prepared by doping Cs2AgBiBr6 with 0.5 mg / mL and 1 mg / mL of the dye molecule Z907 have significantly improved photocurrent responses under zero bias without power supply compared to the undoped Cs2AgBiBr6 device. Among them, for the Cs2AgBiBr6 device doped with 1 mg / mL of the dye molecule Z907, the photocurrent magnitude, responsivity, and detectivity have all increased by about 50% compared to the undoped device. This indicates that the dye molecule Z907 can promote the growth of Cs2AgBiBr6 grains and passivate grain boundaries, which reduces its grain boundary defects and trap states, decreases the non-radiative recombination of carriers, and thus improves the carrier lifetime and mobility. This improvement is conducive to the efficient separation and collection of photo-generated electrons and holes ( Figure 1 b, Figure 2 b, and Figure 3 the SPV spectra of b are also confirmed), thereby improving the overall performance of the self-powered device under zero external bias conditions. However, when the doping amount of the dye molecule Z907 is excessive (2 mg / mL), the photocurrent response of the device decreases significantly. The reasons may include: First, the accumulation of dye molecules at grain boundaries may lead to interface defects and local phase separation, forming a discontinuous or disordered interface layer, thus affecting the overall charge transport and device performance; Second, too many dye molecules may cause an imbalance in the interaction between the solvent and the precursor, changing the originally controlled crystallization process, making the crystallization process too fast or uneven, and then generating more defects and non-ideal crystal phases, ultimately weakening the overall device performance.

Claims

1. Application of Z907 dye in enhancing optoelectronic properties of Cs2AgBiBr6 semiconductor thin film.

2. Use of the Z907 dye as described in claim 1 in enhancing the optoelectronic properties of the Cs2AgBiBr6 semiconductor thin film, characterized in that: The Z907 dye is doped in the Cs2AgBiBr6 semiconductor thin film.

3. The application of the Z907 dye according to claim 2 in enhancing the optoelectronic performance of the Cs2AgBiBr6 semiconductor thin film, characterized in that: The Z907 dye is doped in the precursor solution for preparing the Cs2AgBiBr6 semiconductor thin film, and 0.5 - 2 mg of Z907 dye is added to every 1 mL of the Cs2AgBiBr6 precursor solution.

4. Preparation method of Cs2AgBiBr6 semiconductor thin film, including the following steps Step S1: Clean the FTO conductive glass substrate. Step S2: Dissolve CsBr, AgBr, and BiBr3 together in dimethyl sulfoxide to form a Cs2AgBiBr6 precursor solution. Step S3: Add the Z907 dye to the Cs2AgBiBr6 precursor solution obtained in Step S2, and add 0.5 - 2 mg of Z907 dye to every 1 mL of the Cs2AgBiBr6 precursor solution. Then stir at 110 °C for 1 hour on a heating stage in a nitrogen glove box to obtain a Z907 dye - doped Cs2AgBiBr6 precursor solution. Step S4: Cool the FTO conductive glass substrate obtained in Step S1 and the precursor solution obtained in Step S3 to room temperature in the glove box, filter, and then preheat to 75 °C on a glove box heating plate and hold for 10 minutes. Step S5: Spin - coat the pre - heated precursor solution in Step S4 on the pre - heated FTO conductive glass substrate in the glove box at a speed of 4000 revolutions per minute for 45 seconds, and then immediately place it on a 250 °C heating plate for annealing for 5 minutes.

5. The preparation method of the Cs2AgBiBr6 semiconductor thin film according to claim 4, characterized in that: In Step S1, the FTO conductive glass substrate is cleaned with acetone and isopropanol in ultrasonic waves, then rinsed with deionized water and ethanol, and cleaned with ultraviolet ozone for 30 minutes.

6. The preparation method of the Cs2AgBiBr6 semiconductor thin film according to claim 4, wherein: In Step S2, 1.1 mmol of CsBr, 0.55 mmol of AgBr, and 0.55 mmol of BiBr3 are dissolved together in 1 mL of dimethyl sulfoxide to form 1 mL of Cs2AgBiBr6 precursor solution.

7. The preparation method of the Cs2AgBiBr6 semiconductor thin film according to claim 4, characterized in that: In Step S3, 1 mg of Z907 dye is added to every 1 mL of the Cs2AgBiBr6 precursor solution.

8. Self-powered detector, characterized in that: It is composed of a glass substrate, an FTO layer, a TiO2 electron - transport layer, a Z907 - dye - doped Cs2AgBiBr6 thin film, and a carbon electrode. The Z907 - dye - doped Cs2AgBiBr6 thin film is prepared by the preparation method of the Cs2AgBiBr6 semiconductor thin film as described in Claim 4.

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