Perovskite photoelectric device and preparation method thereof

Abstract

The application relates to a perovskite photoelectric device and a preparation method thereof, and belongs to the technical field of photoelectric detectors. The perovskite photoelectric device comprises a conductive substrate, a perovskite layer, an electron transport layer and a metal electrode in sequence, and a hole transport layer is omitted compared with a traditional photoelectric device; wherein the perovskite layer further comprises an additive, which can reduce thermal residual stress during annealing. The perovskite photoelectric device has high thermal stability and good application prospect.

Description

Technical Field

[0001] This invention relates to the field of photodetector technology, and in particular to a perovskite photoelectric device and its fabrication method. Background Technology

[0002] Near-infrared radiation has a huge demand in fields such as military reconnaissance, imaging and machine vision due to its advantages such as strong penetration and good concealment. Photodetectors are the key devices for converting it into electrical signals.

[0003] In recent years, tin-lead perovskite has become a highly anticipated near-infrared photosensitive material due to its advantages such as narrow bandgap, high light absorption coefficient, long carrier diffusion length, and solution processability. However, the stability and efficiency of tin-lead perovskite photodetectors remain significant issues, particularly stemming from the multilayer structure interfaces of the devices. Among these, the interface transport between the hole transport layer and the perovskite layer is considered a key factor in performance degradation. This interface, the site of nucleation, crystallization, and hole transport, is more prone to carrier transport obstruction, nonradiative recombination losses, and thermal residual stress. In particular, thermal residual stress can cause perovskite lattice distortion, generating local defects such as dislocations and vacancies. These defects, acting as nonradiative recombination centers, accelerate thin film degradation, significantly impairing the stability and thermal stability of the device, thus becoming a major obstacle to its commercialization.

[0004] Therefore, there is an urgent need to develop an optoelectronic device that can improve thermal stability. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a perovskite optoelectronic device based on additives and a hole transport layer and a method for its fabrication.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a perovskite optoelectronic device, comprising, in sequence, a conductive substrate, a perovskite layer, an electron transport layer, and a metal electrode; the perovskite layer comprises a perovskite material and an additive; the additive comprises one or more of 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline], cuprous thiocyanate, 4,4,4-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, N,N'-bis[4-(diphenylamino)phenyl]-N,N'-bis(1-naphthyl)benzidine, and N,N'-bis[4-(diphenylamino)phenyl]-N,N'-di-1-naphthyl-[1,1'-biphenyl]-4,4'-diamine.

[0007] The optoelectronic device of this invention incorporates additives into the perovskite precursor solution. By adding additives to the perovskite layer, stress accumulation during perovskite film annealing is reduced, promoting lattice matching between the perovskite layer and the conductive substrate. This enhances the crystallinity and strength of the perovskite film, reduces the defect density of the perovskite, and significantly improves the thermal stability of the device. Compared to existing technologies, the perovskite optoelectronic device of this invention does not require a hole transport layer, allowing direct contact between the perovskite layer and the conductive substrate. It also simplifies the vertical structure of the device and prevents issues such as carrier transport obstruction, non-radiative recombination loss, and residual thermal stress caused by the hole transport layer from affecting the device's thermal stability.

[0008] In a preferred embodiment of the perovskite optoelectronic device of the present invention, the conductive substrate includes any one of an ITO substrate and an FTO substrate; the electron transport layer comprises SnO2, TiO2, BCP, and PC. 61 One or more of BM and ZrAcac; the perovskite material includes tin-lead perovskite; the metal electrode includes one or more of Cu, Ag, Al, and Au.

[0009] Secondly, the present invention provides a method for fabricating the above-mentioned perovskite optoelectronic device, comprising the following steps: S1. The conductive substrate is ultrasonically cleaned in detergent, deionized water, acetone and ethanol in sequence, and then dried with nitrogen gas flow. S2. Treat the conductive substrate with ultraviolet ozone. S3. Spin-coat a perovskite precursor solution onto the surface of a conductive substrate. Add toluene to the substrate surface during the spin-coating process and anneal twice to obtain a perovskite layer. S4. Spin-coat an electron transport layer solution onto the surface of the perovskite layer to obtain an electron transport layer. S5. Deposit conductive metal onto the surface of the electron transport layer to obtain a perovskite optoelectronic device.

[0010] In a preferred embodiment of the perovskite optoelectronic device fabrication method of the present invention, in step S3, the solute in the perovskite precursor solution includes CsI2, PbI2, FAI, SnI2, additives, Sn powder, and SnF2; the solvent in the perovskite precursor solution includes DMSO and DMF. Using a mixed solvent system of DMSO and DMF can yield a dense, uniform, high-quality perovskite thin film.

[0011] In a preferred embodiment of the perovskite optoelectronic device fabrication method of the present invention, the concentration of the additive is ≥0.5 mg / mL.

[0012] In a preferred embodiment of the perovskite optoelectronic device fabrication method of the present invention, the volume ratio of DMSO to DMF in the precursor solution is (7~7.5):(3~2.5). Within this volume ratio range, the intermediate phase complex formed by DMSO and the solute can synergize well with the rapid volatilization characteristics of DMF, which is beneficial for forming a uniform and dense perovskite thin film.

[0013] In a preferred embodiment of the perovskite optoelectronic device fabrication method of the present invention, in step S3, the spin-coating speed of the perovskite precursor solution is 1900~2100 rpm, the time is 35~45 s, and after adding toluene, spin-coating is performed for another 5~15 s. This spin-coating parameter range can effectively control the solvent evaporation rate and ensure the uniformity of film thickness; toluene, as an anti-solvent, its addition and subsequent spin-coating time setting are conducive to rapid nucleation, resulting in a perovskite film with moderate grain size and a smooth surface.

[0014] In a preferred embodiment of the perovskite optoelectronic device fabrication method of the present invention, the annealing in step S3 includes primary annealing and secondary annealing; the primary annealing temperature is 50~60℃ and the time is 1~2 min; the secondary annealing temperature is 120~130℃ and the time is 5~6 min. By employing a step-by-step annealing process, the low-temperature primary annealing can slowly remove most of the residual solvent, avoiding thin film porosity and cracking caused by excessively rapid solvent evaporation; the subsequent high-temperature secondary annealing can promote further grain growth and fusion, improving the crystallinity and optoelectronic properties of the thin film.

[0015] In a preferred embodiment of the perovskite optoelectronic device fabrication method of the present invention, in step S5, the deposition includes vacuum thermal evaporation; the mass of the conductive metal in the vacuum thermal evaporation is 0.8~1 g; and the vacuum degree during the vacuum thermal evaporation is 4×10⁻⁶. -4 ~6×10 -4 Pa, time 0.9~1.1 h. Vacuum thermal evaporation process can obtain a metal electrode layer with high purity, uniform thickness and density, which is conducive to forming good electrical contact.

[0016] In a preferred embodiment of the perovskite optoelectronic device fabrication method of the present invention, the ultrasonic cleaning time in step S1 is 15-25 min; and the ultraviolet ozone treatment time in step S2 is 35-45 min. Within the above-mentioned ultraviolet ozone treatment time, the wettability of the substrate surface can be sufficiently improved and organic residues can be further removed, which is beneficial to the uniform deposition of the subsequent electron transport layer and the quality of interface contact.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: The perovskite optoelectronic device of the present invention eliminates the perovskite hole transport layer by adding additives to the perovskite precursor solution, thus alleviating thermal residual stress and overcoming the problem of poor thermal stability of organic-inorganic hybrid perovskite vertical structure photodetectors in the prior art. In imaging and other fields, it can transmit signals completely and stably and take clear pictures, and has broad application prospects. Attached Figure Description

[0018] Figure 1 The graph shows the thermal stability test results of Example 1 at 80°C. Figure 2 The graph shows the thermal stability test results of Example 1 at 100°C. Figure 3 The graph shows the thermal stability test results of Comparative Example 1 at 80℃. Figure 4 The graph shows the thermal stability test results of Comparative Example 2 at 80℃. Figure 5 The figure shows the thermal stability test results of Example 2 at 80°C. Detailed Implementation

[0019] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0020] Unless otherwise specified, all other materials and reagents used in the examples are commercially available.

[0021] Example 1 One embodiment of the perovskite optoelectronic device of the present invention, wherein the conductive substrate of this embodiment is an ITO substrate and the electron transport layer is composed of PC. 61 BM (50nm), ZrAcac (100nm), the perovskite layer composition is FA 0.85 Cs 0.15 Sn 0.5 Pb 0.5 I3 (1000nm), the metal electrode is a Cu electrode (140nm).

[0022] The perovskite optoelectronic device fabrication method described in this embodiment is as follows: S1. The conductive substrate is ultrasonically cleaned in detergent, deionized water, acetone and ethanol for 20 min in sequence, and then dried with nitrogen gas flow. S2. Treat the conductive substrate with ultraviolet ozone for 40 minutes. S3. Dissolve 77.8 mg CsI2, 461 mg PbI2, 282 mg FAI, 378 mg SnI2, 1 mg 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline], 12 mg Sn powder and 0.78 mg SnF2 powder in a mixed solution of 1 mL DMSO and DMF to obtain a perovskite precursor solution; S4. Spin-coat the perovskite precursor solution onto the conductive substrate surface at 2000 rpm for 40 s, then add toluene to the substrate surface and spin-coat for 10 s. Anneal twice under a nitrogen atmosphere: first at 60°C for 1 min, then at 130°C for 5 min, to obtain FA. 0.85 Cs 0.15 Sn 0.5 Pb 0.5 I3 perovskite thin films; S5, PC is applied to the surface of the perovskite layer. 61 BM solution was spin-coated at 1200 rpm for 60 seconds onto PC. 61 A ZrAcac solution was spin-coated onto the surface of the BM layer at 3000 rpm for 30 s to obtain an electron transport layer. S6. Using a single-chamber high-vacuum resistance coating apparatus, place the sample obtained in step S5 into the sample chamber, prepare 1.15 g of metallic Cu, and set the apparatus vacuum degree to 5 × 10⁻⁶. -4 The perovskite optoelectronic device was obtained by depositing copper onto the sample through thermal evaporation at a temperature of 1200℃ for 1 hour.

[0023] Example 2 An embodiment of the perovskite optoelectronic device of the present invention differs from Example 1 only in that: in step S3 of Example 1, the 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline additive is replaced with N,N'-bis[4-(diphenylamino)phenyl]-N,N'-di-1-naphthyl-[1,1'-biphenyl]-4,4'-diamine, while the other steps are the same as in Example 1.

[0024] Comparative Example 1 The present invention provides a comparative example of a perovskite optoelectronic device, which differs from Example 1 only in that: after step S2 in Example 1, three drops of PEDOT:PSS are spin-coated at 3000 rpm for 40 s, and then annealed at 140°C for 20 min to obtain a hole transport layer.

[0025] Comparative Example 2 The present invention provides a comparative example of a perovskite optoelectronic device, which differs from Example 1 only in that: in step S3 of Example 1, 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline additive is not added, while the other steps are the same as in Example 1.

[0026] Example of effect 1 This example examines the thermal stability of the perovskite device of the present invention. Specifically, the perovskite optoelectronic device was connected to a resistor to form a circuit, and an LED was used to continuously illuminate the device. Stability tests were conducted on the perovskite device at different temperatures, and the voltage across the resistor was continuously measured using an oscilloscope. The test results are shown in Tables 1-3. Figures 1-5 As shown.

[0027] Table 1 Table 2 Table 3 As can be seen from Tables 1-3, perovskite optoelectronic devices with the additives of the present invention can maintain stability at high temperatures, while perovskite optoelectronic devices without the additives of the present invention have poor stability at lower operating temperatures.

[0028] Figure 1 The results of the thermal stability test of Example 1 at 80°C show that when there is no hole transport layer and 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline] is added to the perovskite precursor solution, the thermal stability of the perovskite optoelectronic device provided by the present invention is more than 3 hours longer than that of the comparative example, from the minute level to the hour level. After working continuously at 80°C for 3 hours, its thermal stability drops to about 15% of the initial value.

[0029] Figure 2 The results of the thermal stability test of Example 1 at 100°C show that when there is no hole transport layer and 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline is added to the perovskite precursor solution, the thermal stability of the perovskite optoelectronic device provided by the present invention decreases by approximately 15% of its initial value after operating continuously at 100°C for 3 hours. Figure 3 In the thermal stability test results of Comparative Example 1 at 80℃, when there is a hole transport layer and no additives are added to the perovskite precursor solution, its thermal stability reaches the highest point of 80% after heating at 80℃ for only 1 minute, and then drops to 50% after 4 minutes, indicating that the device has basically failed.

[0030] Figure 4To compare the thermal stability test results of Example 2 at 80℃, when there is no hole transport layer and no 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline] is added to the perovskite precursor solution, its thermal stability reaches the highest point of 80% after heating at 80℃ for only 1 minute, and then drops to 50% after 4 minutes, indicating that the device has basically failed.

[0031] Figure 5 The results of the thermal stability test at 80°C for Example 2 show that when there is no hole transport layer and N,N'-bis[4-(diphenylamino)phenyl]-N,N'-di-1-naphthyl-[1,1'-biphenyl]-4,4'-diamine is added to the perovskite precursor solution, the thermal stability of the perovskite optoelectronic device provided by the present invention reaches the hour level. After working continuously at 80°C for 120 minutes, its performance did not decrease. However, after working continuously at 80°C for 150 minutes, the performance decreased by about 19% of the initial value.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A perovskite optoelectronic device, characterized in that, The material comprises, in sequence, a conductive substrate, a perovskite layer, an electron transport layer, and a metal electrode; the perovskite layer comprises perovskite material and additives; the additives comprise one or more of the following: 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline], cuprous thiocyanate, 4,4,4-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, N,N'-bis[4-(diphenylamino)phenyl]-N,N'-bis(1-naphthyl)benzidine, and N,N'-bis[4-(diphenylamino)phenyl]-N,N'-di-1-naphthyl-[1,1'-biphenyl]-4,4'-diamine.

2. The perovskite optoelectronic device as described in claim 1, characterized in that, The conductive substrate includes either an ITO substrate or an FTO substrate; the electron transport layer comprises SnO2, TiO2, BCP, and PC. 61 The perovskite material comprises one or more of BM and ZrAcac, including tin-lead perovskite; the metal electrode comprises one or more of Cu, Ag, Al, and Au.

3. A method for fabricating a perovskite optoelectronic device as described in any one of claims 1 to 2, characterized in that, Includes the following steps: S1. The conductive substrate is ultrasonically cleaned in detergent, deionized water, acetone and ethanol in sequence, and then dried with nitrogen gas flow. S2. Treat the conductive substrate with ultraviolet ozone. S3. Spin-coat a perovskite precursor solution onto the surface of a conductive substrate. Add toluene to the substrate surface during the spin-coating process and anneal twice under a nitrogen atmosphere to obtain a perovskite layer. S4. Spin-coat an electron transport layer solution onto the surface of the perovskite layer to obtain an electron transport layer. S5. Deposit conductive metal onto the surface of the electron transport layer to obtain a perovskite optoelectronic device.

4. The method for fabricating the perovskite optoelectronic device as described in claim 3, characterized in that, In step S3, the solutes in the perovskite precursor solution include CsI2, PbI2, FAI, SnI2, additives, Sn powder, and SnF2; the solvents in the perovskite precursor solution include DMSO and DMF.

5. The method for fabricating the perovskite optoelectronic device as described in claim 4, characterized in that, The concentration of the additive is 0.52 mg / mL.

6. The method for fabricating the perovskite optoelectronic device as described in claim 4, characterized in that, The volume ratio of DMSO to DMF in the precursor solution is (7~7.5):(3~2.5).

7. The method for fabricating the perovskite optoelectronic device as described in claim 3, characterized in that, In step S3, the spin coating speed of the perovskite precursor solution is 1900~2100 rpm, the time is 35~45 s, and after adding toluene, spin coating is performed for another 5~15 s.

8. The method for fabricating the perovskite optoelectronic device as described in claim 3, characterized in that, The annealing in step S3 includes primary annealing and secondary annealing; the temperature of primary annealing is 50~60℃ and the time is 1~2 min; the temperature of secondary annealing is 120~130℃ and the time is 5~6 min.

9. The method for fabricating the perovskite optoelectronic device as described in claim 3, characterized in that, In step S5, the deposition includes vacuum thermal evaporation; the mass of the conductive metal in the vacuum thermal evaporation is 0.8~1 g; and the vacuum degree during the vacuum thermal evaporation is 4×10⁻⁶. -4 ~6×10 -4 Pa, time is 0.9~1.1 h.

10. The method for fabricating the perovskite optoelectronic device as described in claim 3, characterized in that, The ultrasonic cleaning time in step S1 is 15-25 min; the ultraviolet ozone treatment time in step S2 is 35-45 min.

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