A perovskite layer, its preparation method, and a perovskite solar cell using the same layer.

Abstract

This invention discloses a perovskite layer, its preparation method, and a perovskite solar cell. The invention utilizes sarcosine hydrochloride (SH) additive for front-interface doping and a Sn-Pb perovskite precursor solution. Sarcosine modulates the energy level at the buried interface, further increasing the degree of N-type doping, improving hole transport, and reducing non-radiative recombination. Simultaneously, the sarcosine at the bottom can stabilize cations, forming more nucleation sites, improving crystallinity, and enhancing the quality of the bottom interface of the perovskite film, thereby improving the photovoltaic performance of the device. This method is not only effective in single-junction narrow-bandgap perovskite solar cells but also shows great promise for application in tandem perovskite solar cells.

Description

Technical Field

[0001] This invention belongs to the field of perovskite solar cell technology, specifically relating to a perovskite layer, its preparation method, and a perovskite solar cell using the layer. Background Technology

[0002] All-perovskite tandem solar cells have shown great potential in breaking the Shockley-Quiselle limit of single-junction solar cells. Double-ended all-perovskite tandem solar cells (TSCs) have overcome the physical limitations of traditional single-junction solar cells, recently achieving power conversion efficiencies exceeding 30%. Such high photoelectric conversion efficiency (PCE) is achieved through a wide bandgap (E... g This level (~1.7-1.9 eV) was achieved through continuous improvements in the electronic performance of perovskite top cells. Improving propulsion efficiency remains a key priority for all-perovskite tandem solar cells, but progress in Pb-Sn hybrid narrow-bandgap subcells has limited the achievement of this goal.

[0003] Hybrid Sn-Pb narrow-bandgap perovskite solar cells (PSCs) can achieve bandgaps of approximately 1.2–1.3 eV, overcoming the theoretical efficiency of their lead analogues. However, this also introduces some problems, such as Sn… 2+ It is easily oxidized to Sn 4+ This leads to defect formation and increased nonradiative recombination. Furthermore, the reaction between SnI2 and MAI / FAI is much faster than that with PbI2, and noticeable pinholes easily appear when the Sn content exceeds 25%. The rapid and uncontrolled crystallization process of perovskite materials results in surface inhomogeneities and reduces carrier diffusion length. Moreover, the doping and energy states (intrinsic, n-type, or p-type) of perovskite semiconductors can be significantly influenced by the polarity of the underlying functional layer and the stoichiometry of the perovskite. In conclusion, improving the optoelectronic properties of narrow bandgap materials is extremely challenging.

[0004] At the perovskite / HTL interface, photogenerated holes can be readily extracted and transferred to the anode. Electrons generated near the perovskite / HTL interface need to traverse hundreds of nanometers of the perovskite film to reach the electron transport layer. This imbalanced charge transport is a significant factor degrading the photovoltaic performance of pin PSCs. To achieve high-efficiency pin PSCs, the doping level of the perovskite needs to be converted to a higher n-type doping level.

[0005] n-type doping is an important technique for studying electron transfer processes and enhancing the n-type properties of materials. In recent years, n-type additive engineering, including organic and inorganic dopants, has been widely used to bond with perovskite thin films and manipulate their electronic states. Furthermore, the wide-bandgap n-type semiconductor 4,6-bis(3,5-bis(pyridine-4))phenyl)-2-phenylpyrimidine (B4PyPPM) has been used to raise the Fermi level of perovskite thin films, promoting electron extraction to the electron transport layer (ETL), resulting in a PCE of 23.51% for p-in PSCs. Therefore, n-type doping of organic semiconductors is an attractive option due to their tunable molecular structures, good compatibility with perovskites, and passivation effects from specific functional groups.

[0006] Inorganic dopants such as Ba, Sb, or Bi cations have more valence electrons and exhibit n-type doping characteristics. They are used to partially replace Pb cations, but the incorporation of metal ions may lead to severe ion migration, which is detrimental to the performance and stability of the device. Summary of the Invention

[0007] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0008] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0009] Therefore, the object of the present invention is to overcome the shortcomings of the prior art and provide a perovskite layer.

[0010] To solve the above-mentioned technical problems, the present invention provides the following technical solution: including,

[0011] It consists of a bottom interface pre-doped with sarcosine hydrochloride and a perovskite material layer in bulk doped with sarcosine hydrochloride.

[0012] The bottom interface is obtained by spin-coating and annealing a passivation solution with a concentration of 0.1~0.5 mg / mL formed by dissolving sarcosine hydrochloride in DMF solution.

[0013] The perovskite material layer is made of sarcosine hydrochloride dissolved in FA. 0.6 MA 0.3 Cs 0.1 Sn 0.5 Pb 0.5The perovskite material solution with a concentration of 4-6 mg / mL was formed in the I3 narrow bandgap perovskite precursor solution and then subjected to spin coating, annealing, and back passivation treatment.

[0014] As a preferred embodiment of the perovskite layer of the present invention, the spin coating speed of the passivation solution is 1500~3000 rpm and the time is 20~30s.

[0015] In a preferred embodiment of the perovskite layer of the present invention, the annealing temperature of the passivation solution is 100~110℃ and the annealing time is 3~5min.

[0016] As a preferred embodiment of the perovskite layer of the present invention, the spin coating of the perovskite material solution is a two-step spin coating. The first step spin coating speed is 1000~2000 rpm and the time is 10~20s; the second step spin coating speed is 3000~5000 rpm and the time is 40~50s.

[0017] As a preferred embodiment of the perovskite layer described in this invention, chlorobenzene, the anti-solvent, is added dropwise during the second spin coating process.

[0018] As a preferred embodiment of the perovskite layer of the present invention, the annealing temperature of the perovskite material solution is a two-step annealing, first annealing on a hot stage at 100~110℃ for 8~10 min, and then annealing on a hot stage at 65~70℃ for 5~8 min to obtain a perovskite film.

[0019] Another object of the present invention is to provide a perovskite solar cell.

[0020] To solve the above-mentioned technical problems, the present invention provides the following technical solution: including using the perovskite layer as a narrow bandgap perovskite absorber layer to prepare a narrow bandgap perovskite solar cell.

[0021] In a preferred embodiment of the perovskite solar cell described in this invention, its structure comprises, from bottom to top, the following components:

[0022] ITO conductive glass layer with a thickness of 800~1000 nm;

[0023] Hole transport layer, 30~50 nm;

[0024] Narrow bandgap perovskite absorber layer with a thickness of 800~1000 nm;

[0025] Electron transport layer, 20~30 nm;

[0026] Hole blocking layer, 20~30 nm;

[0027] Metal electrode layer, 100~200 nm;

[0028] The narrow bandgap perovskite absorber layer material is the aforementioned perovskite layer.

[0029] In a preferred embodiment of the perovskite solar cell of the present invention, the hole transport layer is made of PEDOT:PSS material, and the electron transport layer is made of C. 60 The hole blocking layer material is BCP, and the metal electrode layer material is copper.

[0030] Another object of the present invention is to provide a tandem perovskite solar cell.

[0031] To solve the above-mentioned technical problems, the present invention provides the following technical solution: applying the above-mentioned narrow bandgap perovskite solar cell with a 1.77 eV wide E... g -FA 0.8 Cs 0.2 Pb(I) 0.6 Br 0.4 By combining the top sub-cells, a 2T all-perovskite TSCs tandem perovskite solar cell is obtained.

[0032] Beneficial effects of this invention:

[0033] (1) Developing efficient N-type molecular dopants is an urgent need for preparing high-performance pi-nPSCs, because the doping efficiency of N (electron) doping is very low and more difficult than that of P (hole) doping. The proposed method in this application achieves a high degree of n-type doping in perovskite films through SH, which leads to the expansion of the quasi-Fermi level splitting (QFLS) in the perovskite and increases the VOC to 0.894V. In the bulk, the interaction between the ammonium group, the carboxyl group of the dopant and the uncoordinated Sn atom suppresses Sn. 2+ The oxidation effectively passivates the trapped states, which helps reduce carrier recombination and increases the fill factor (FF) to 80.3%.

[0034] (2) In this invention, sarcosine hydrochloride (SH) additive is used to dope the Sn-Pb perovskite precursor solution at the front interface. Sarcosine is used to modulate the energy level of the buried interface, further increasing the degree of N-type doping, improving the transport with the hole transport layer, and reducing non-radiative recombination. At the same time, the sarcosine at the bottom can also stabilize cations, form more nucleation sites, improve crystallization, and improve the film quality of the bottom interface of the perovskite film, thereby improving the photovoltaic performance of the device.

[0035] (3) The method of the present invention is not only effective in single-junction narrow bandgap perovskite solar cells, but also has good application prospects in tandem perovskite solar cells. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0037] Figure 1 This is a schematic diagram of the structure of the solar cell prepared in Example 1 of the present invention.

[0038] Figure 2 This is a passivation schematic diagram of the solar cells prepared in Embodiment 1 and Comparative Examples 1 and 2 of the present invention.

[0039] Figure 3 Sn in the X-ray photoelectron spectra obtained in Embodiment 1 and Comparative Examples 1 and 2 of the present invention 2+ and Sn 4+ Peak fitting plot.

[0040] Figure 4 The image shows the 3d peak shift of Sn in the X-ray photoelectron spectra obtained in Example 1 and Comparative Examples 1 and 2 of this invention.

[0041] Figure 5 The images shown are SEM images of narrow bandgap perovskite sections obtained in Embodiment 1 and Comparative Examples 1 and 2 of the present invention.

[0042] Figure 6 The images shown are SEM images of the narrow bandgap perovskite buried interface obtained in Embodiment 1 and Comparative Examples 1 and 2 of the present invention.

[0043] Figure 7 The image shows the FTIR spectra of sarcosine hydrochloride (SH) and formamidinium hydroiodide (FAI) dissolved in deuterated DMSO solution in Example 1 of this invention.

[0044] Figure 8 This is the nuclear magnetic resonance (NMR) image of sarcosine hydrochloride (SH) and formamidinium hydroiodide (FAI) dissolved in deuterated DMSO solution in Example 1 of the present invention.

[0045] Figure 9 The XRD diffraction patterns of the narrow bandgap perovskite thin films prepared in Example 1 and Comparative Examples 1 and 2 are shown.

[0046] Figure 10 The full width at half maximum (FWHM) of the 100 diffraction peak is shown in the XRD diffraction patterns of the narrow bandgap perovskite thin films prepared in Example 1 and Comparative Examples 1 and 2.

[0047] Figure 11 The above are UPS diagrams of the narrow bandgap perovskite thin films prepared in Example 1 and Comparative Examples 1 and 2.

[0048] Figure 12 The JV curves are for the narrow bandgap perovskite solar cells prepared in Example 1 and Comparative Examples 1 and 2.

[0049] Figure 13 The EQE curves of narrow bandgap perovskite solar cells prepared in Example 1 and Comparative Examples 1 and 2 are shown.

[0050] Figure 14 This is a cross-sectional SEM image of the all-perovskite tandem solar cell device prepared in Example 4.

[0051] Figure 15 The JV curve is shown for the all-perovskite tandem solar cell device prepared in Example 4.

[0052] Figure 16 The EQE curve is shown for the all-perovskite tandem solar cell device prepared in Example 4.

[0053] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0054] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0055] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0056] Unless otherwise specified, all raw materials used in this invention are commercially available.

[0057] In this invention, the product performance is tested according to the following method:

[0058] Power conversion efficiency: Under 100 mW cm-2AM 1.5G solar simulator illumination (SS-F5-3A, Enlitech), light intensity was measured using a Keithley 2400 source meter and calibrated with a standard silicon solar cell.

[0059] Open-circuit voltage: Under 100 mW cm-2AM 1.5G solar simulator illumination (SS-F5-3A, Enlitech), the light intensity was measured using a Keithley 2400 source meter and calibrated with a standard silicon solar cell.

[0060] EQE testing: EQE measurements were performed using the EQE system (QE-R, Enlitech) under near-dark testing conditions.

[0061] X-ray photoelectron spectroscopy (XPS) analysis was performed on the perovskite thin film using an ESCALAB 250Xi (Thermal Fisher Scientific) spectrometer.

[0062] Nuclear magnetic resonance (NMR) test: The solution was tested by dissolving the material in deuterated DMSO using a Bruker 400MHz laser from Germany.

[0063] Fourier transform infrared (FTIR) spectroscopy: The material was dissolved in deuterated DMSO and analyzed using a Perkin-Elmer Spectrum GX spectrometer.

[0064] XRD testing: X-ray diffraction of the perovskite thin film was performed using an X'Pert PRO MPD to analyze its diffraction pattern.

[0065] UPS testing: Using a Thermo ESCALAB 250XI, flat perovskite thin films were tested to obtain the valence band top, work function, and corresponding energy level diagrams.

[0066] Scanning electron microscopy (SEM) tests: The top view of the perovskite thin film was characterized using field emission scanning electron microscopes (Hitachi S-4800 and ZEISS Sigma 300).

[0067] Example 1

[0068] Reference Figure 1 This is a schematic diagram of a narrow bandgap perovskite solar cell. This embodiment provides a method for fabricating a narrow bandgap perovskite solar cell doped with sarcosine hydrochloride. Specifically:

[0069] 1) Clean the ITO conductive glass layer. Select ITO conductive glass with sheet resistance of 15Ω, average transmittance >85%, and thickness of 0.7 mm as the substrate material. Clean it in an ultrasonic cleaner for 20 minutes in sequence with detergent, deionized water, acetone, and ethanol. Then, dry the cleaned ITO conductive glass with a nitrogen gun and treat it with ultraviolet ozone for 25 minutes to remove surface organic matter and obtain a clean ITO conductive glass layer.

[0070] 2) The hole transport layer material PEDOT:PSS solution was spread on the ITO conductive glass layer and then spin-coated at a speed of 6000 rpm for 40 s. After spin-coating, the substrate was placed on a hot plate at 150 ℃ for annealing for 20 minutes to obtain a hole transport layer with a thickness of 30 nm.

[0071] 3) Dissolve sarcosine hydrochloride powder in DMF solution to obtain a passivation solution with a concentration of 0.3 mg / mL. Drop 80 μL of the passivation solution onto the hole transport layer for one-step spin coating. The spin coating speed is 2000 rpm and the time is 30 s. After spin coating, place it on a hot stage at 100℃ for annealing for 5 min to obtain a perovskite passivation layer. This step is named Buried.

[0072] 4) FA was prepared by dissolving 0.9 mmol lead iodide, stannous iodide, 1.08 mmol formamidin hydroiodate, 0.54 mmol methylamine hydroiodate, 0.18 mmol cesium iodide, 5 mmol% stannous fluoride, and 3.5 mmol% lead thiocyanate in a DMF / DMSO mixed solvent at a volume ratio of 3:1. 0.6 MA 0.3 Cs 0.1 Sn 0.5 Pb 0.5 I3 perovskite material solution;

[0073] The perovskite material solution was filtered through a 0.22 μm polytetrafluoroethylene (PTFE) membrane, and the solution was stirred at room temperature to obtain a clear and transparent FA solution. 0.6 MA 0.3 Cs 0.1 Sn 0.5 Pb 0.5 I3 narrow bandgap perovskite precursor solution, this step is named Bulk;

[0074] Sarcosine hydrochloride powder dissolved in FA 0.6 MA 0.3 Cs 0.1 Sn 0.5 Pb 0.5 In the I3 narrow bandgap perovskite precursor solution, a perovskite material solution with a doping concentration of 4.5 mg / mL of sarcosine hydrochloride was obtained.

[0075] 5) Drop 70 μL of perovskite material solution doped with sarcosine hydrochloride onto the perovskite passivation layer prepared in step 4) and perform a two-step spin coating. The first spin coating speed is 1000 rpm and the time is 10 s.

[0076] The second spin coating process involves a spin coating speed of 4000 rpm and a time of 50 s. In the 20th second of the second spin coating process, 600 μL of chlorobenzene is dropped onto the substrate as an anti-solvent.

[0077] After spin coating, the substrate was placed on a hot stage at 100°C for annealing for 10 min, and then placed on a hot stage at 65°C for annealing for 7 min to obtain a perovskite film with a thickness of 800 nm.

[0078] 6) Dissolve ethylenediamine iodine powder in IPA solution to obtain a back passivation solution with a concentration of 1 mg / mL. Drop 80 μL of the back passivation solution onto the perovskite film prepared in step 5), and then spin-coat at 4000 rpm for 20 s. Immediately afterward, anneal at 100 ℃ for 5 minutes to form a narrow bandgap perovskite back passivation layer.

[0079] 7) Place the product obtained in step 6) in a thermal evaporation chamber, and heat it at 4 × 10⁻⁶ ℃. -4 Under a high vacuum of Pa, 25 nm of C60 material was sequentially deposited as an electron transport layer, 6 nm of BCP was deposited as a hole blocking layer, and 100 nm of copper was deposited as a metal electrode layer to obtain the narrow bandgap perovskite solar cell doped with sarcosine hydrochloride in this embodiment, denoted as SH(Buried+Bulk).

[0080] Figure 1 This is a schematic diagram of the narrow bandgap single-junction solar cell fabricated in this embodiment. As can be seen from the figure, the fabricated perovskite solar cell is an inverted nip structure. Comparative Example 1

[0081] The difference between this comparative example and Example 1 is that step 3 is omitted. All other steps and processes are the same as in Example 1. The perovskite thin film, narrow bandgap perovskite absorber layer and narrow bandgap perovskite solar cell of this comparative example are obtained and are denoted as SH(Bulk). Comparative Example 2

[0082] The difference between this comparative example and Example 1 is that step 3) is omitted, and sarcosine hydrochloride is not doped in step 4). The remaining steps are the same as in Example 1. The perovskite thin film, narrow bandgap perovskite absorber layer and narrow bandgap perovskite solar cell of this comparative example are obtained and are referred to as Control.

[0083] The narrow bandgap perovskite solar cells prepared in Example 1 and Comparative Examples 1-2 were subjected to relevant performance tests, and the results are shown in Table 1.

[0084] Table 1

[0085] PCE / % <![CDATA[ V OC / V]]> FF / % <![CDATA[ J SC / mA / cm 2 ]]> Control 20.45 0.862 75.7 31.35 SH(Bulk) 22.68 0.885 80.4 31.88 SH (Buried + Bulk) 23.26 0.893 80.3 32.44

[0086] It can be seen that the addition of sarcosine hydrochloride to the perovskite material allows sarcosine to coordinate with uncoordinated metal cations, passivating bulk defects and suppressing nonradiative recombination. Due to the addition of sarcosine at the bottom interface, SH at the interface acts as a bridge, connecting the bottom interface and enhancing hole extraction. Simultaneously, SH can modulate the perovskite energy levels to promote carrier transport at the interface. Furthermore, SH has the ability to regulate perovskite layer growth, which is beneficial for forming large grain sizes and high-quality films. This modulation effectively reduces defects and mitigates nonradiative charge recombination.

[0087] Figure 2 The diagram shows the passivation of narrow bandgap perovskite films prepared in Example 1 and Comparative Examples 1 and 2. As can be seen from the figure, in the perovskite body, the functional group amino of the dopant passivates the defects of the perovskite film by combining with the negatively charged defects, and adjusts the energy level structure of the perovskite. Moreover, it mainly acts on the front interface. Therefore, we added a sarcosine interface layer to the front interface, and further modulate the energy level by sarcosine at the bottom interface, and provide nucleation sites to improve subsequent crystallization.

[0088] Figure 3 X-ray photoelectron spectroscopy (Sn) of the narrow bandgap perovskite thin films prepared in Example 1 and Comparative Examples 1 and 2 2+ and Sn 4+ (Peak fitting diagram) shows that, after bulk doping with SH, the effect of Sn on Sn was reduced to a certain extent. 4+ The peak value indicates that Sn was suppressed. 2+ The oxidation was further suppressed when added to the bottom interface, possibly due to the reduction of tin vacancies at the bottom interface, which suppressed defect states at the bottom and improved device performance.

[0089] Figure 4 The X-ray photoelectron spectroscopy (XPS) spectra of the narrow bandgap perovskite films prepared in Example 1 and Comparative Examples 1 and 2 (3d peak shift diagrams of Sn) show that the 3d peak of Sn shifts towards lower binding energies, indicating an increase in electron cloud density around the Sn atom. This is attributed to the interaction between the carboxyl group in sarcosine and the uncoordinated Sn atoms in the perovskite. 2 + The COO-Sn interaction between them.

[0090] Figure 5The images show SEM cross-sectional images of the narrow bandgap perovskite films prepared in Example 1 and Comparative Examples 1 and 2. As can be seen, the introduction of sarcosine into the perovskite mass improved the crystallinity to some extent. However, the cross-sectional SEM images reveal numerous pores at the buried interface of the perovskite. These undesirable pores are attributed to the incomplete evaporation of non-volatile solvent additives, such as dimethyl sulfoxide (DMSO), resulting in a defect density approximately two orders of magnitude higher than at the center of the perovskite film. These defects can negatively impact the subsequent crystallization process. Therefore, we introduced sarcosine into the buried interface to improve the subsequent crystallization process by increasing the number of anchoring points.

[0091] Figure 6 The images show SEM buried cross-sectional images of the narrow bandgap perovskite films prepared in Example 1 and Comparative Examples 1 and 2. It can be seen that there are obvious voids at the bottom grain boundaries of the control group film. After bulk doping, the crystallization of perovskite is improved to a certain extent, and the perovskite grains are enlarged, but there are still some pores. After the bottom interface is treated, we found that the grains are more compact and the film quality is significantly improved.

[0092] Figure 7 Fourier transform infrared (FTIR) spectroscopy analysis of sarcosine hydrochloride (SH) and formamidine hydroiodide (FAI) dissolved in deuterated DMSO solution in Example 1 characterized the interaction between sarcosine and perovskite. After the addition of sarcosine to FAI, the stretching vibration of the C=O double bond shifted to a lower wavenumber by 13 cm⁻¹. -1 We attribute this transformation to the formation of a coordinate bond between the carboxyl group and FAI. The change in strength is due to the interaction between the lone pair electrons of the oxygen atom and the ammonium group of FAI. The strong electron-withdrawing effect of the ammonium group transfers some of the electron density to FAI.

[0093] Figure 8 The nuclear magnetic resonance (NMR) measurements of sarcosine hydrochloride (SH) and formamidine hydroiodide (FAI) dissolved in deuterated DMSO solution in Example 1 were performed to investigate the interaction between sarcosine and the major A-site formamidine (FA) cation. As shown in the figure, the signal of NH protons in FAI appeared at 8.8 ppm. After the addition of SH, the signal showed a slight shift and splitting at 7.8 ppm and 8.8 ppm. We believe that the introduction of sarcosine can enable its carboxyl group to form a strong hydrogen bond with FAI. The carboxyl group of SH can limit FA by forming non-covalent hydrogen bonds. + The dynamic movement of ions. Therefore, multiple active nucleation sites are formed on the buried interface of perovskite, which is conducive to the precise and controllable growth of perovskite, and plays a crucial role in promoting the growth of larger perovskite grains.

[0094] Figure 9 The XRD diffraction patterns of the narrow bandgap perovskite films prepared in Example 1 and Comparative Examples 1 and 2 are shown. All films exhibit significant diffraction peaks at (110) and (220). SH doping enhances the diffraction peak at 110, and this enhancement is further amplified when combined with treatment of the bottom interface. This indicates an increase in perovskite crystallinity, consistent with the improved crystal quality observed in the SEM images.

[0095] Figure 10 The image shows the full width at half maximum (FWHM) of the 100 diffraction peak in the XRD diffraction patterns of the narrow bandgap perovskite films prepared in Example 1 and Comparative Examples 1 and 2. It can be seen that the crystallinity of the film is significantly improved.

[0096] Figure 11 The ultraviolet photoelectron spectroscopy (UPS) spectra of the narrow bandgap perovskite films prepared in Example 1 and Comparative Examples 1 and 2 are shown to further verify the n-type doping effect of SH dopant and to investigate the influence of sarcosinate on the valence electron structure of the perovskite films. The cutoff and eonset were observed in the UPS spectra of the control group and films with different SH passivation methods. The cutoff showed a shift from 16.53 eV to 16.22 eV. The energy level diagram shown in the figure was constructed using UPS and relevant references. After modification, both the conduction band bottom (CBM) and valence band top (VBM) of the perovskite shifted upwards, with an overall bias towards n-type semiconductor. The perovskite modified with the buried interface exhibited the energy level arrangement most favorable for hole extraction from the hole transport layer.

[0097] Figure 12 The graphs shown are the optimal JV performance curves for the narrow bandgap perovskite solar cells prepared in Example 1 and Comparative Examples 1 and 2. It can be seen that the turn-on voltage (TUV) of the device was improved when only bulk doping was performed. Subsequently, the TCV was further improved after adding dopant at the bottom interface. This is attributed to the improved film quality at the bottom interface.

[0098] Figure 13 The graphs show the optimal EQE performance of the narrow bandgap perovskite solar cells prepared in Example 1 and Comparative Examples 1 and 2. It can be seen that the current of the device was improved, and the current was further improved after the addition of a film at the bottom interface, which is attributed to the improved film quality at the bottom interface.

[0099] Example 2

[0100] The difference between this embodiment and Embodiment 1 is that step 3) is omitted, and the doping concentration of the perovskite material solution doped with sarcosine hydrochloride in step 4) is adjusted to 0, 1.5, 3.0, 4.5, and 6 mg / mL, respectively. The remaining steps are the same as in Embodiment 1, resulting in narrow bandgap perovskite solar cells with different sarcosine hydrochloride doping concentrations in this embodiment.

[0101] The narrow bandgap perovskite solar cells prepared in this embodiment were subjected to relevant performance tests, and the results are shown in Table 2.

[0102] Table 2

[0103] SH concentration (mg / mL) PCE / % <![CDATA[ V OC / V]]> FF / % <![CDATA[ J SC / mA / cm 2 ]]> 0 20.45 0.862 75.7 31.35 1.5 21.52 0.872 78.5 31.44 3 22.13 0.879 79.7 31.60 4.5 22.68 0.885 80.4 31.88 6 22.29 0.881 79.2 31.95

[0104] As shown in Table 2, adjusting the sarcosine concentration has a significant impact on the performance of solar cells. This is because the adjustment of additives affects the morphology and conductivity of the perovskite film. Appropriate additives can promote effective crystallization in the perovskite film, forming a more ordered structure and improving carrier mobility and transport performance. Excessive concentration leads to the introduction of too many sarcosine hydrochloride molecules into the crystal lattice, generating impurity-level energy levels that affect carrier transport and lifetime; insufficient concentration results in no effective effect. According to the results in Table 1, the optimal sarcosine concentration of 4.5 mg / mL achieves the best technical results in this invention.

[0105] Example 3

[0106] The difference between this step and Example 1 is that the concentration of sarcosine hydrochloride in the passivation solution in step 3) is adjusted to 0, 0.1, 0.3, and 0.5 mg / mL, respectively. The remaining steps are the same as in Example 1, resulting in narrow bandgap perovskite solar cells with different concentrations of sarcosine hydrochloride doped in the passivation solution of this example.

[0107] The narrow bandgap perovskite solar cells prepared in this embodiment were subjected to relevant performance tests, and the results are shown in Table 3.

[0108] Table 3

[0109] Buried concentration (mg / mL) PCE / % <![CDATA[ V OC / V]]> FF / % <![CDATA[ J SC / mA / cm 2 ]]> 0 22.68 0.885 80.4 31.88 0.1 22.51 0.884 79.6 31.98 0.3 23.26 0.893 80.3 32.44 0.5 22.70 0.886 79.4 32.27

[0110] As shown in Table 3, due to the addition of sarcosine at the bottom interface, SH at the interface acts as a bridge, connecting the bottom interface and enhancing hole extraction. Simultaneously, SH can modulate the perovskite energy levels to promote carrier transport at the interface. Furthermore, SH has the ability to regulate perovskite layer growth, which is beneficial for forming large grain sizes and high-quality films. This modulation effectively reduces defects and mitigates non-radiative charge recombination. Comparative Example 3

[0111] The difference between this comparative example and Example 1 is that SH in steps 3) and 4) is adjusted to cysteine ​​salt (Cys), which has a similar structure. The remaining steps are the same as in Example 1. The resulting solar cell is denoted as Cys(Buried+Bulk). Comparative Example 4

[0112] The difference between this comparative example and Example 1 is that SH in steps 3) and 4) is adjusted to glycine hydrochloride (Gly), an amino acid salt with a similar structure. The remaining steps are the same as in Example 1. The resulting solar cell is denoted as Gly(Buried+Bulk). Comparative Example 5

[0113] The difference between this comparative example and Comparative Example 1 is that SH is adjusted to be cysteine ​​salt (Cys), an amino acid salt with a similar structure. The remaining steps are the same as those in Comparative Example 1, and the solar cell of this comparative example is obtained, which is denoted as Cys(Bulk). Comparative Example 6

[0114] The difference between this comparative example and Comparative Example 1 is that SH is adjusted to glycine hydrochloride (Gly), an amino acid salt with a similar structure. The remaining steps are the same as those in Comparative Example 1, and the solar cell of this comparative example is obtained and denoted as Gly(Bulk).

[0115] The narrow bandgap perovskite solar cells prepared in Comparative Examples 3 to 6 were subjected to relevant performance tests and compared with Example 1 and Comparative Examples 1 and 2. The results are shown in Table 4.

[0116] Table 4

[0117] PCE / % <![CDATA[ V OC / V]]> FF / % <![CDATA[ J SC / mA / cm 2 ]]> Control 20.45 0.862 75.7 31.35 SH (Buried + Bulk) 23.26 0.893 80.3 32.44 Cys(Buried+Bulk) 22.14 0.882 78.5 31.98 Gly (Buried+Bulk) 22.67 0.884 79.7 32.18 SH(Bulk) 22.68 0.885 80.4 31.88 Cys(Bulk) 21.53 0.875 77.2 31.88 Gly (Bulk) 21.99 0.881 78.3 31.89

[0118] As can be seen from Table 4, these amino acids with similar structures can improve the photovoltaic performance of devices by regulating the growth of perovskite, reducing defects, and inhibiting non-radiative recombination, under the premise of in vivo passivation and passivation of the bottom interface. However, SH has a significant advantage in regulating the effect. Comparative Example 7

[0119] The difference between this comparative example and Example 1 is that the SH in steps 3) and 4) is adjusted to formamidine sulfinate (FSA), which has reducing properties. The remaining steps are the same as in Example 1, and the solar cell of this comparative example is obtained, denoted as Cys(Buried+Bulk). Comparative Example 8

[0120] The difference between this comparative example and Comparative Example 1 is that SH is adjusted to formamidine sulfinate (FSA), which has reducing properties. The remaining steps are the same as those in Comparative Example 1, and the solar cell of this comparative example is obtained, denoted as Cys(Bulk).

[0121] The narrow bandgap perovskite solar cells prepared in Examples 7-8 were subjected to relevant performance tests and compared with Example 1 and Comparative Examples 1 and 2. The results are shown in Table 5.

[0122] Table 5

[0123] PCE / % <![CDATA[ V OC / V]]> FF / % <![CDATA[ J SC / mA / cm 2 ]]> Control 20.45 0.862 75.7 31.35 SH(Bulk) 22.68 0.885 80.4 31.88 FSA (Bulk) 22.27 0.881 79.2 31.91 SH (Buried+Bulk) 23.26 0.893 80.3 32.44 FSA (Buried + Bulk) 21.56 0.863 78.4 31.86

[0124] As shown in Table 5, replacing the in-vivo additive with formamidine sulfinate (FSA) has strong reducing properties and can effectively coordinate with metal cations, thus effectively passivating in-vivo defects. Therefore, it can improve device performance under in-vivo additive conditions. However, when treated with a method similar to sarcosine, the device performance actually decreases. It is speculated that the interaction site of FSA with perovskite is not focused on the bottom interface. Instead of strong interaction with perovskite at the bottom interface, it leads to recombination at the interface, thereby deteriorating the photovoltaic performance of the device.

[0125] Example 4

[0126] This embodiment provides a 2T all-perovskite TSCs tandem perovskite solar cell based on Embodiment 1, specifically:

[0127] The narrow bandgap perovskite solar cell prepared in Example 1 was compared with a 1.77 eV wide E-bandgap solar cell. g -FA 0.8 Cs 0.2 Pb(I) 0.6 Br 0.4 By combining the top sub-cells, a 2T all-perovskite TSCs tandem perovskite solar cell is obtained.

[0128] Figure 14 The cross-sectional SEM structure of the all-perovskite tandem solar cell fabricated in this embodiment shows that the device structure is glass / ITO / 4PDCB / wide Eg perovskite / C 60 / SnO2 / ITO / PEDOT:PSS / EDADI+HM low E g Perovskite / C 60 / BCP / Cu.

[0129] Figure 15The JV curves for the all-perovskite tandem solar cell fabricated in this embodiment show that the SH-doped all-perovskite tandem solar cell achieved an optimal PCE of 29.02% (28.79%) during the reverse (forward) voltage scan, with a voltage rating of 2.154 (2.147) V. V OC 16.38 (16.31) mA / cm 2 of J SC The FF was 82.2% (82.2%), and the hysteresis factor was 0.79. This indicates that SH doping can further improve the performance of tandem perovskite solar cells by enhancing the performance of single-junction narrow bandgap cells, and has great application prospects.

[0130] Figure 16 The EQE spectrum of the all-perovskite tandem solar cell prepared in this embodiment shows the EQE integrals of the corresponding top and bottom sub-cells. J SC The values ​​were 15.82 and 15.83 mA / cm, respectively. 2 This indicates that the current density matching between the two sub-cells is good after SH doping;

[0131] In summary, this invention discloses a perovskite material doped with sarcosine hydrochloride, its preparation method, and a perovskite solar cell, used as a perovskite absorber layer. Simultaneous treatment at both the bulk and buried interface introduces an efficient N-type doping method, improving the energy level arrangement of the perovskite to promote transport relative to the hole transport layer. This also improves the crystallization of the narrow bandgap and the film quality at the buried interface. Furthermore, applying this method to amino acid hydrochloride with a similar structure demonstrates that it can further improve photovoltaic performance and achieve optimal passivation.

[0132] 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 it. 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 spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A perovskite layer, characterized in that: include, It consists of a bottom interface pre-doped with sarcosine hydrochloride and a perovskite material layer in bulk doped with sarcosine hydrochloride. The bottom interface is obtained by spin-coating and annealing a passivation solution with a concentration of 0.1-0.5 mg / mL formed by dissolving sarcosine hydrochloride in DMF solution. The perovskite material layer is made of sarcosine hydrochloride dissolved in FA. 0.6 MA 0.3 Cs 0.1 Sn 0.5 Pb 0.5 The perovskite material solution with a concentration of 4-6 mg / mL was formed in the I3 narrow bandgap perovskite precursor solution and then subjected to spin coating, annealing, and back passivation treatment.

2. The perovskite layer as described in claim 1, characterized in that: The passivation solution was spin-coated at a speed of 1500–3000 rpm for 20–30 s.

3. The perovskite layer as described in claim 2, characterized in that: The annealing temperature of the passivation solution is 100–110°C, and the annealing time is 3–5 min.

4. The perovskite layer as described in claim 1, characterized in that: The spin coating of the perovskite material solution is a two-step spin coating. The first step spin coating speed is 1000-2000 rpm and the time is 10-20 s. The second step spin coating speed is 3000-5000 rpm and the time is 40-50 s.

5. The perovskite layer as described in claim 4, characterized in that: In the second step of spin coating, the anti-solvent chlorobenzene is added dropwise.

6. The perovskite layer as described in any one of claims 1, 4, or 5, characterized in that: The annealing temperature of the perovskite material solution is a two-step annealing process: first, annealing on a hot stage at 100-110°C for 8-10 minutes, and then annealing on a hot stage at 65-70°C for 5-8 minutes to obtain a perovskite film.

7. A perovskite solar cell, characterized in that: Narrow bandgap perovskite solar cells are prepared by using the perovskite layer described in any one of claims 1 to 6 as a narrow bandgap perovskite absorber layer.

8. The perovskite solar cell according to claim 7, characterized in that: Its structure, from bottom to top, includes the following: The ITO conductive glass layer has a thickness of 800–1000 nm; Hole transport layer, 30–50 nm; Narrow bandgap perovskite absorber layer with a thickness of 800–1000 nm; Electron transport layer, 20–30 nm; Hole blocking layer, 20–30 nm; Metal electrode layer, 100–200 nm; The narrow bandgap perovskite absorber layer material is the perovskite layer described in any one of claims 1 to 6.

9. The perovskite solar cell as described in claim 8, characterized in that: The hole transport layer is made of PEDOT:PSS, and the electron transport layer is made of C. 60 The hole blocking layer material is BCP, and the metal electrode layer material is copper.

10. A tandem perovskite solar cell, characterized in that: Applying the perovskite solar cell of claim 7, the narrow bandgap perovskite solar cell is combined with a 1.77 eV wide E... g -FA 0.8 Cs 0.2 Pb(I 0.6 Br 0.4 By combining the top sub-cells, a 2T all-perovskite TSCs tandem perovskite solar cell is obtained.

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