Room-temperature continuous-wave perovskite lasers based on chiral amine ligands and preparation methods thereof

Abstract

The present invention discloses a room-temperature continuous-wave perovskite laser based on a chiral amine ligand and a preparation method thereof. By using a chiral amine ligand, a quasi-two-dimensional perovskite thin film with an ordered phase distribution, strong crystallization orientation and low lattice distortion degree is obtained. These characteristics endow the thin film with the following advantages: an excellent four-level material structure system, enhanced carrier pumping efficiency, which is beneficial to population inversion and reduces the laser threshold; enhanced energy transfer efficiency between the low two-dimensional phase (n = 1) and the high two-dimensional phase (n > 5); increased number and strength of hydrogen bonds with the perovskite octahedral framework, effectively suppressing the electroacoustic coupling effect and other advantages. The prepared chiral quasi-two-dimensional perovskite is used as a gain medium and combined with an optical resonator to prepare a laser, which can achieve room-temperature low-threshold continuous-wave or pulsed laser emission under the pumping of various coherent light sources. The threshold is 1-3 orders of magnitude lower than that of traditional semiconductor lasers, and the optimized threshold can reach 1.57 W / cm<supgt;2< / supgt;.

Description

Technical Field

[0001] The present invention relates to the technical field of optoelectronic devices, and particularly to a room-temperature continuous-wave perovskite laser based on chiral amine ligands and a preparation method thereof. Background Art

[0002] In the post-Moore era, micro-nano integrated photonic devices have become an indispensable core component in the process of information operation and transmission. With the increasing integration requirements, traditional electronic devices face various bottlenecks, such as limitations in response speed, energy consumption, modulation, and bandwidth. Due to the advantages of photons, including ultra-high-speed propagation, low loss, and diverse modulation methods, photonic-based circuits have the potential to overcome these limitations and enhance the functions of electronic devices. Macroscopic free optical paths (optical paths) have demonstrated capabilities in transmission and logic operations, including waveguide propagation, directional beam splitting, intensity modulation, and phase modulation. However, manufacturing highly integrated large-scale photonic circuits remains a challenge. Therefore, on-chip integrated photonic devices and circuits have become an ideal solution and have received extensive attention. Although significant progress has been made in the research of silicon-based integrated photonic devices, the efficient and low-cost heterogeneous integration based on group-IV and III-V coherent light sources remains a difficult problem. Therefore, active integrated photonic circuits using novel gain materials are crucial for future integrated photonics research. In the past decade, a class of emerging direct-bandgap semiconductor materials, metal halide perovskites, has received extensive attention due to their high gain coefficient, low defect state concentration, wide wavelength tuning, and easy silicon photon integration characteristics. In addition, single-crystalline perovskite microstructures with regular and special morphologies have demonstrated excellent laser and waveguide properties. Given these advantages, perovskite semiconductors are considered a promising platform for realizing micro-nano light sources and photonic devices at room temperature. In traditional lasers, the generation of laser must satisfy the following three basic conditions: population inversion, threshold phenomenon, and optical feedback. Population inversion means that the number of particles at a higher energy level must be greater than the number of particles at a lower energy level. Therefore, most low-threshold lasers usually have a four-level energy band structure. Pure two-dimensional (2D) and three-dimensional (3D) perovskites belong to single-phase substances, and their behavior is similar to a three-level laser system. In contrast, quasi-two-dimensional (quasi-2D) perovskites can be regarded as a four-level system, and their stability is increased. However, at present, the problem of uneven phase distribution easily occurs in quasi-two-dimensional perovskites, which leads to disordered states in space and energy, increases non-radiative recombination channels, reduces energy transfer efficiency, and is difficult to form a standard four-level structure state, which is not conducive to population inversion and the final emission of laser. In addition, due to the soft lattice structure characteristics of perovskites, the excited-state carriers (excitons) are prone to exciton-phonon coupling with lattice vibrations, which will greatly affect the carrier transport and the realization of final stimulated emission amplification. Summary of the Invention

[0003] In view of the deficiencies of the prior art, the present application proposes a room-temperature continuous-wave perovskite laser based on a chiral amine ligand and a preparation method thereof.

[0004] According to the first aspect of the embodiments of the present application, a room-temperature continuous-wave perovskite laser based on a chiral amine ligand is provided, including:

[0005] An optical microcavity, a gain medium, and a spacer layer, wherein the gain medium is sandwiched between the optical microcavity and the spacer layer, and a reflective layer is deposited on the spacer layer:

[0006] The gain medium is a hybrid material including a perovskite material, which is uniformly distributed in the optical microcavity in the form of a thin film with a thickness of 10 nm to 1 mm;

[0007] The composition of the perovskite material is A’ 2 A n-1 B n X 3n+1 , where A’ is an organic chiral amine ion, A is a monovalent cation, B is a divalent metal cation, X is an anion, and n is a positive integer; A’ is one or a combination of more of S / R-p-bromo-1-phenylethylamine s-Br-MBA, S-α-methylbenzylamine s-MBA, S / R-1-naphthylethylamine S / R-1-NEA, and S / R-2-aminobutane; A is cesium ion Cs + , methylammonium ion MA + , formamidinium ion FA + , ethylammonium ion EA + , guanidinium ion GA + , isopropylammonium ion IPA + in one or a combination of more; B is lead ion Pb 2+ , tin ion Sn 2+ , germanium ion Ge 2+ , indium ion In 2+ , bismuth ion Bi 2+ in one or a combination of more; X is chloride ion Cl - , bromide ion Br - , iodide ion I - in one or a combination of more.

[0008] Furthermore: The hybrid material includes one or more of organic small molecule materials, organic polymer materials, inorganic oxide materials, III-V group materials, II-VI group materials, rare earth materials, and the perovskite material, reducing the perovskite defect density.

[0009] Further: The type of the optical microcavity is a Distributed Bragg Reflector (DBR), a Distributed Feedback Laser (DFB), a Photonic Crystal (PC), a Bound states in the continuum (BIC), a Topological Photonic Crystal (TC), or a Whispering Gallery Mode (WGM) microcavity, which enhances the interaction between light and matter and promotes laser emission.

[0010] According to the second aspect of the embodiments of the present application, a method for preparing a room-temperature continuous-wave perovskite laser based on a chiral amine ligand is provided, which is used to prepare the room-temperature continuous-wave perovskite laser based on a chiral amine ligand as described in the first aspect, and specifically includes the following steps:

[0011] Prepare an optical microcavity as the bottom reflective layer;

[0012] Prepare a gain medium: Mix A’X, AX, and BX 2 in a solvent to obtain a perovskite precursor solution; spin-coat or drop-coat the perovskite precursor solution on the bottom reflective layer, and anneal and crystallize it to obtain the gain medium;

[0013] Spin-coat a polymer on the gain medium to form a spacer layer;

[0014] Evacuate the air, and form a top reflective layer on the spacer layer by thermal evaporation.

[0015] Further: On quartz, sapphire, or a flexible substrate polyethylene terephthalate (PET), deposit a dielectric layer of multi-layer silica / tantalum pentoxide by sputtering or electron beam evaporation to form a Distributed Bragg Reflector, that is, the bottom reflective layer; the thickness of each dielectric film is λ / 4n, where λ is the emission center wavelength of the gain medium, and n is the refractive index of the dielectric layer material.

[0016] Further: Before spin-coating or drop-coating the perovskite precursor solution on the bottom reflective layer, perform an oxygen plasma etching treatment on the bottom reflective layer to enhance the hydrophilicity of the substrate surface, which is beneficial to the complete spreading of the solution and the subsequent spin-coating process.

[0017] Furthermore: 0.5% mol molecular additives are also added to the perovskite precursor solution, and it is filtered through a polytetrafluoroethylene hydrophobic filter membrane. The solvent is any one or a mixture of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), γ-butyrolactone (GBL), and dimethylacetamide (DMA); the molecular additives are a mixture of one or more of polymers, small molecules, and oxides. The polymers are a mixture of one or more of polymethyl methacrylate (PMMA), polyethylene glycol (PEG), polyethylene oxide (PEO), and polyvinylpyrrolidone (PVP); the small molecules are a mixture of one or more of potassium bromide (KBr), potassium thiocyanate (KSCN), methylammonium chloride (MACl), and phenethylammonium bromide; the oxides are a mixture of one or more of NiOx, ZnO, and SnO 2 to reduce the defect density during the film formation process.

[0018] Furthermore: The molar ratio of A’X, AX, and BX 2 is 2:1:1 - 2:3:4. It is spin-coated into a film by the spin-coating method at a rotational speed of 2000 - 6000 rpm for 30 - 60 s, and a uniform gain layer film with high crystallinity and low roughness can be formed.

[0019] Furthermore: When the polymer is spin-coated on the gain medium, the rotational speed is 2000 - 6000 rpm and the time is 30 - 60 s, and a uniform spacer layer film with high crystallinity and low roughness can be formed.

[0020] Furthermore: Vacuum pumping is performed to reduce the metal evaporation temperature. When the vacuum degree reaches 5×10 -5 Pa, silver metal is evaporated onto the spacer layer to form a top reflective layer with a reflectivity > 99%.

[0021] The technical solutions provided by the embodiments of the present application may include the following beneficial effects:

[0022] 1. This method uses solution methods and other low-cost methods to prepare high-quality quasi-two-dimensional perovskite films (i.e., gain media) based on chiral amine ligands. By using chiral amine ligands, a highly ordered phase distribution, strong crystallization preferred orientation, and low lattice distortion degree are obtained; these characteristics enable the film to have: an excellent four-level material structure system, enhanced carrier pumping efficiency, which is beneficial for population inversion; enhanced energy transfer efficiency between the low two-dimensional phase (n = 1) and the high two-dimensional phase (n > 5); increased number and strength of hydrogen bonds with the perovskite octahedral framework, effectively suppressing the electroacoustic coupling effect and other advantages. Combining the prepared perovskite film with a high-quality optical microcavity, its threshold is 1 - 3 orders of magnitude lower than that of traditional semiconductor lasers. The laser threshold under continuous optical pumping is 1.57 mW / cm 2 , which is the lowest threshold in current perovskite single-mode / multimode lasers;

[0023] 2. The perovskite lasers prepared by this method can be combined with various incoherent or coherent light sources (such as commercial III-V light-emitting diodes (LEDs), organic light-emitting diodes (OLEDs), quantum dot light-emitting diodes (QD-LEDs), perovskite light-emitting diodes (PeLEDs), micro light-emitting diodes (micro-LEDs), laser diodes (LDs), tungsten halogen lamps, etc.) to construct an electrically pumped perovskite laser chip.

[0024] 3. The laser devices prepared by this method have good temporal and spatial coherence and good polarization characteristics, and can be further used in fields such as low-threshold coherent light sources, slow light devices, quantum computing, optical computing, photonic chips, optoelectronic integration, etc.

[0025] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit this application. Description of the Drawings

[0026] The drawings herein are incorporated into the specification and constitute a part of this specification, showing embodiments consistent with this application, and are used together with the specification to explain the principles of this application.

[0027] Figure 1 Schematic diagram of the mechanism of the quasi-two-dimensional perovskite laser based on chiral amine and achiral ligand prepared in Example 1;

[0028] Figure 2 Schematic diagram of the comparison characterization of the absorption and emission spectra and emission quantum efficiency of the quasi-two-dimensional perovskite based on chiral amine and achiral ligand prepared in Example 1;

[0029] Figure 3 Schematic diagram of the comparison characterization of the stimulated emission amplification and threshold of the quasi-two-dimensional perovskite based on chiral amine and achiral ligand prepared in Example 1;

[0030] Figure 4 Schematic diagram of the comparison characterization of the transient absorption spectrum and energy transfer efficiency of the quasi-two-dimensional perovskite based on chiral amine and achiral ligand prepared in Example 1;

[0031] Figure 5 Schematic diagram of the preparation of a continuous-wave perovskite laser based on chiral amine ligand and the characterization of laser threshold and laser coherence in Example 1;

[0032] Figure 6 Schematic diagram of the comparison characterization of the stimulated emission amplification of the quasi-two-dimensional perovskite based on chiral amine and achiral ligand prepared in Example 2;

[0033] Figure 7Schematic diagram of comparative characterization of amplified stimulated emission of quasi-two-dimensional perovskites based on chiral amines and achiral ligands prepared in Example 3;

[0034] Figure 8 Schematic diagram of comparative characterization of amplified stimulated emission of quasi-two-dimensional perovskites based on chiral amines and achiral ligands prepared in Example 4. Detailed implementation manners

[0035] Here, the exemplary embodiments will be described in detail, and the examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation manners described in the following exemplary embodiments do not represent all implementation manners consistent with the present application.

[0036] The terms used in the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The singular forms "a", "the" and "said" used in the present application are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0037] The present invention will be further explained and described below with reference to the accompanying drawings.

[0038] Example 1

[0039] This example introduces a preparation method of a room-temperature continuous-wave quasi-two-dimensional perovskite laser based on a chiral amine ligand. The specific steps are as follows:

[0040] Step 1: Place a 1.1-mm-thick quartz glass substrate in an ultrasonic machine and clean it successively with deionized water and ethanol for 10 minutes. After cleaning and drying the glass substrate in a vacuum oven, place it on a sample holder; Place the sample holder with the glass substrate in an electron beam evaporation coater and perform a vacuum pumping process. When the vacuum degree reaches 4×10 -4 Pa, successively evaporate SiO 2 , Ta 3 O 5 onto the quartz glass substrate for 7 groups, control the evaporation rate at 0.4 nm / s, the thickness of each layer of SiO 2 is 63.21 nm, and the thickness of each layer of Ta 3 O 5 is 93.57 nm to form a DBR bottom reflection layer with a high reflectivity (>98%).

[0041] Step 2: Etch the dried DBR bottom reflection layer with oxygen plasma for 8 - 15 minutes.

[0042] Step 3: Dissolve the material with a molar ratio of S-Br-MBABr / Rac-Br-MBABr : FABr: PbBr 2  = 2:1:2 in a mixed solvent of DMF and DMSO with a concentration of 1 mL to form a perovskite precursor solution with a concentration of 0.5 mol L -1 , where the ratio of DMF to DMSO is 1:4.

[0043] Step 4: Filter 50 μL of the perovskite precursor solution through a PTFE hydrophobic filter membrane and evenly drop-coat it on the bottom reflective layer of the DBR; adjust the spin-coating time of the spin coater to 60 s, control the spin-coating speed at 5000 rpm / min, and drop the chlorobenzene solution from the top small hole at the 45th second after starting the spin-coating; place the DBR bottom reflective layer coated with the perovskite precursor solution on a hot stage for annealing, anneal at 100 °C for 10 minutes to form a 100-nm-thick perovskite light-emitting layer, that is, a gain medium in the form of a perovskite thin film.

[0044] Step 5: Weigh 10 - 200 mg of polymethyl methacrylate (PMMA) powder and dissolve it in solvents such as chlorobenzene or toluene for later use.

[0045] Step 6: Spin-coat a spacer layer of PMMA optical microcavity on the perovskite thin film to enhance the cavity length. The concentration of the PMMA solution is 220 mg / ml, the spin-coating speed is 5000 rpm, and it is cured by heating on a hot stage at 120 °C for 10 min after spin-coating.

[0046] Step 7: Load the sample obtained in Step 4 into a thermal evaporation coating machine for vacuum pumping. When the vacuum degree reaches 5×10 -5 Pa, evaporate metal silver on the sample with a thickness of 320 nm to form a top reflective layer with a reflectivity > 99%. After waiting for the thermal evaporation to complete, take the device out of the evaporation chamber, and the laser is fabricated.

[0047] Place the laser on an upright microscope stage, focus the continuous laser with a wavelength of 405 nm through a 10X objective lens onto the gain medium layer of the device, place a wheel-type neutral density filter in front of the laser to adjust the excitation intensity. Place a polarizer in front of the spectrometer detector and rotate the angle of the polarizer to measure the polarization of the generated laser beam. The emitted light beam of the quasi-two-dimensional laser based on chiral amine ligands is split into two beams by a beam splitter. One part passes through the beam splitter and continues to move forward (reference arm), and the other part is reflected (signal arm). These two beams of light reach the mirror on the other side through different paths, are reflected back again and recombine through the beam splitter to measure the temporal and spatial coherence of the light beam.

[0048] Figure 1Schematic diagram for comparing the mechanisms of achieving amplified stimulated emission in quasi-two-dimensional perovskite films based on chiral and achiral amine ligands. As can be seen from the schematic diagram, in the quasi-two-dimensional perovskite film, under excitation with energy higher than the bandgap, excitons in the valence band absorb energy and jump to the conduction band. The high-energy hot excitons gradually cool to the band-edge energy level through scattering collisions and electron-phonon coupling. In addition, both quasi-two-dimensional perovskites prepared based on chiral and achiral amine ligands can form a four-level structure. However, compared with chiral amines, although the quasi-two-dimensional perovskite film prepared with achiral amines can also form a four-level structure, due to the weaker strength and smaller number of hydrogen bonds between the achiral amine and the perovskite octahedron, the overall lattice structure stability is worse, and the excited-state carriers are prone to strong coupling with the lattice, resulting in lower energy transfer efficiency and difficulty in achieving population inversion. After excitation with energy higher than the bandgap, only fluorescence signals of radiative recombination appear, and no amplified stimulated emission signal is observed.

[0049] Figure 2 In a, it is a schematic diagram of the phase distribution of the quasi-two-dimensional film. The prepared perovskite film has an n-value distribution of n = 1 and a three-dimensional phase. Figure 2 In b, it is the absorption spectrum and fluorescence spectrum of the quasi-two-dimensional films based on chiral and achiral amines. The absorption spectrum shows that both have only two absorption peaks at n = 1 and the three-dimensional phase, indicating an ordered phase distribution. The fluorescence spectrum shows only the fluorescence emission peak of the three-dimensional phase, indicating effective energy transfer from the two-dimensional to the three-dimensional phase. However, the fluorescence intensity of the chiral one is stronger than that of the achiral one, indicating a more rapid and efficient energy transfer mechanism, which is the key to achieving low-threshold amplified stimulated emission. Figure 2 In c, it is the fluorescence quantum yield of the corresponding quasi-two-dimensional film. This result is consistent with the fluorescence spectrum, also indicating that the quasi-two-dimensional film based on chiral amines has higher energy transfer efficiency.

[0050] Figure 3 In a and Figure 3 In b, it is the photoluminescence spectra of the quasi-two-dimensional perovskite films prepared based on chiral and achiral amines as a function of the pump energy. For the film sample based on chiral amines, under ultraviolet excitation, as the pump energy increases, the amplified stimulated emission signal peak gradually appears. Then, for the achiral film, only fluorescence signals are always observed, indicating that its threshold is very high or it is difficult to achieve population inversion and thus no amplified stimulated emission can occur. Figure 3 In c, it is a schematic diagram of the characterization of the change in luminescence intensity and full width at half maximum as a function of the pump energy drawn according to Figure 3 In a. From the figure, the amplified stimulated emission threshold of the chiral amine quasi-two-dimensional perovskite film can be calculated to be 7.95 μj / cm 2To further determine the energy transfer efficiency, we characterized two thin film samples by transient absorption spectroscopy, extracted the n = 1 exciton absorption peak and the carrier dynamics curve at the three-dimensional phase, and quantitatively calculated the energy transfer efficiency. Figure 4 a in Figure 4 and b in Figure 4 are the 2D maps of the measured transient absorption spectra. It can be clearly seen that compared with the achiral amine sample, the absorption at the exciton peak of the chiral amine-based two-dimensional thin film hardly disappears, and the carrier energy is quickly transferred to the three-dimensional phase. Additionally, according to

[0051] Based on the amplified stimulated emission achieved in the quasi-two-dimensional perovskite thin film prepared with the above chiral amine ligand, we spin-coated the perovskite thin film on the bottom distributed Bragg reflector (DBR) mirror, then spin-coated PMMA on the perovskite thin film, and finally evaporated a silver mirror (320 nm) on the top to fabricate a vertical cavity surface emitting (VCSEL) green laser ( Figure 5 a in 2 / Ta 2 O 5 dielectric layers to ensure a high reflectivity (>98%). The bottom DBR mirror and the top silver mirror show high reflectivities (98.50% and 99.93%) at a wavelength of about 550 nm ( Figure 5 b in Figure 5 ). Since the thickness of the perovskite thin film is only about 100 nm, a layer of polymethyl methacrylate (PMMA) spacer layer is added to increase the cavity length. 2 Figure 5 c in Figure 5 shows the characterization of the laser intensity and the full width at half maximum as a function of the pump power density intensity. It can be calculated that the laser threshold is 1.57 W / cm Figure 5 d in

[0052] Example 2

[0053] This example introduces a preparation method of a room-temperature continuous-wave quasi-two-dimensional perovskite laser based on a chiral amine ligand. The specific steps are as follows:

[0054] ​Step 1: Place a 1.1-mm-thick quartz glass substrate in an ultrasonic cleaner and clean it successively with deionized water and ethanol for 10 minutes. After cleaning and wiping it dry, place the glass substrate in a vacuum oven for drying, and then put the dried glass substrate into a sample holder. Load the sample holder with the glass substrate into an electron beam coating machine and perform a vacuum pumping process. When the vacuum degree reaches 4×10 -4 Pa, successively evaporate SiO 2 , Ta 3 O 5 onto the quartz glass substrate for 7 sets. Control the evaporation rate at 0.4 nm / s. The thickness of each layer of SiO2 is 63.21 nm, and the thickness of each layer of Ta 3 O 5 is 93.57 nm to form a DBR bottom reflective layer with a high reflectivity (>98%).

[0055] Step 2: Subject the dried DBR bottom reflective layer to oxygen plasma etching treatment for 8 - 15 minutes.

[0056] Step 23: Dissolve the material with a molar ratio of S-MBABr / Rac-MBABr : FABr: PbBr 2  = 2:1:1 in a mixed solvent of DMF and DMSO with a concentration of 1 mL to form a 0.5 mol L -1 perovskite precursor solution, where the ratio of DMF to DMSO is 1:4.

[0057] Step 34: Filter 50 μL of the perovskite precursor solution through a polytetrafluoroethylene hydrophobic filter membrane and then uniformly drop-coat it on the DBR bottom reflective layer. Adjust the spin-coating time of the spin coater to 60 s, control the spin-coating speed at 5000 rpm / min, and drop chlorobenzene solution from the top small hole at the 45th second after starting spin-coating. Place the DBR bottom reflective layer coated with the perovskite precursor solution on a hot stage for annealing at 100 °C for 10 minutes to form a 100-nm-thick perovskite light-emitting layer, that is, a gain medium in the form of a perovskite thin film.

[0058] Step 5: Weigh 10 - 200 mg of polymethyl methacrylate (PMMA) powder and dissolve it with solvents such as chlorobenzene or toluene for later use;

[0059] Step: 6: Spin-coat a PMMA optical microcavity spacer layer on the perovskite thin film to enhance the cavity length. The concentration of the PMMA solution is 220 mg / ml, the spin-coating speed is 5000 rpm, and after spin-coating, heat it on a hot stage at 120 °C for 10 minutes for curing.

[0060] Step 57: Load the sample obtained in Step 4 into a thermal evaporation coating machine and perform a vacuum pumping process. When the vacuum degree reaches 5×10-5 At 4×10⁻⁴ Pa, silver metal is evaporated onto the sample with a thickness of 320 nm to form a top reflective layer with a reflectivity > 99%. After the thermal evaporation is completed, the device is taken out of the evaporation chamber, and the laser is fabricated.

[0061] Place the fabricated device on an upright microscope stage. Focus the femtosecond laser with a wavelength of 343 nm onto the gain medium layer of the device through a 10X objective lens. Place a wheel-type attenuator in front of the laser to adjust the excitation intensity. Place a polarizer in front of the spectrometer detector and rotate the angle of the polarizer to measure the polarization of the generated laser beam. Figure 6 a in Figure 6 b in Figure 6 is the photoluminescence spectrum of the quasi-two-dimensional perovskite thin film prepared based on chiral and achiral amines as a function of the pump energy. For the thin film sample based on chiral amines, under the excitation of ultraviolet light, as the pump energy increases, the amplified spontaneous emission signal peak gradually appears, and then the achiral thin film is always a fluorescence signal, indicating that its threshold is very high or it is difficult to achieve population inversion and thus the amplified spontaneous emission cannot occur. Figure 6 c in 2 is a schematic diagram showing the variation of the emission intensity and the full width at half maximum as a function of the pump energy plotted according to b in

[0062] Example 3

[0063] This example introduces a preparation method of a room-temperature continuous-wave quasi-two-dimensional perovskite laser based on chiral amine ligands. The specific steps are as follows:

[0064] Step 1: Place a 1.1-mm-thick quartz glass substrate in an ultrasonic cleaner and clean it successively with deionized water and ethanol for 10 minutes. After cleaning and wiping, put the dried glass substrate into a vacuum oven and then place it on a sample holder. Load the sample holder with the glass substrate into an electron beam evaporation machine and perform a vacuum pumping process. When the vacuum degree reaches 4×10⁻⁴ -4 Pa, successively evaporate SiO 2 , Ta 3 O 5 onto the quartz glass substrate for 7 groups, controlling the evaporation rate at 0.4 nm / s. The thickness of each layer of SiO 2 is 63.21 nm, and the thickness of each layer of Ta 3 O 5 is 93.57 nm to form a DBR bottom reflective layer with a high reflectivity (> 98%).

[0065] Step 2: Treat the dried DBR bottom reflector layer by oxygen plasma etching for 8 - 15 min.

[0066] Step 23: Dissolve the material with a molar ratio of S-2-BABr / Rac-2-BABr : FABr: PbBr 2  = 2:1:1 in a mixed solvent of DMF and DMSO with a concentration of 1 mL to form a 0.5 mol L -1 perovskite precursor solution, where the ratio of DMF to DMSO is 1:4.

[0067] Step 34: After filtering 50 μL of the perovskite precursor solution through a polytetrafluoroethylene hydrophobic filter membrane, evenly drop-coat it on the DBR bottom reflector layer; adjust the spin-coating time of the spin coater to 60 s, control the spin-coating speed at 5000 rpm / min, and drop chlorobenzene solution from the top small hole at the 45th s after starting spin-coating; place the DBR bottom reflector layer spin-coated with the perovskite precursor solution on a hot plate for annealing, anneal at 100 °C for 10 minutes to form a 100-nm-thick perovskite light-emitting layer, that is, a gain medium in the form of a perovskite thin film.

[0068] Step 5: Weigh 10 - 200 mg of polymethyl methacrylate (PMMA) powder and dissolve it in a solvent of chlorobenzene or toluene for later use;

[0069] Step 6: Spin-coat a spacer layer of PMMA optical microcavity on the perovskite thin film to enhance the cavity length. The concentration of the PMMA solution is 220 mg / ml, the spin-coating speed is 5000 rpm, and after spin-coating, heat it on a hot plate at 120 °C for 10 min for curing.

[0070] Step 57: Load the sample obtained in Step 4 into a thermal evaporation coating machine and perform vacuum pumping. When the vacuum degree reaches 5×10 -5 Pa, evaporate metal silver on the sample with a thickness of 320 nm to form a top reflector layer with a reflectivity > 99%. After waiting for the thermal evaporation to complete, take the device out of the evaporation chamber, and the laser is fabricated.

[0071] Place the fabricated device on an upright microscope stage, focus the femtosecond laser with a wavelength of 343 nm through a 10X objective lens on the gain medium layer of the device, place a wheel-type attenuator in front of the laser to adjust the excitation intensity. Place a polarizer in front of the spectrometer detector and rotate the angle of the polarizer to measure the polarization of the generated laser beam. Figure 7 in a and Figure 7In this case, b is the photoluminescence spectrum of quasi-two-dimensional perovskite thin films prepared based on chiral and achiral amines as a function of pump energy. For the thin film sample based on chiral amines, under the excitation of ultraviolet light, as the pump energy increases, the amplified spontaneous emission signal peak gradually appears. Then, for the achiral thin film, it is always a fluorescence signal, indicating that its threshold is very high or it is difficult to achieve population inversion and thus the amplification of stimulated emission cannot occur. The pattern observed in this system is the same as that in Example 1. Other laser proof test steps are omitted, and mainly Example 1 is used for detailed description.

[0072] Example 4

[0073] This example introduces a preparation method of a room-temperature continuous-wave quasi-two-dimensional perovskite laser based on chiral amine ligands. The specific steps are as follows:

[0074] Step 1: Place a 1.1-mm-thick quartz glass substrate in an ultrasonic cleaner and clean it successively with deionized water and ethanol for 10 minutes. After cleaning and wiping it dry, put the glass substrate into a vacuum oven for drying, and then place the dried glass substrate on a sample holder; Put the sample holder with the glass substrate into an electron beam coating machine and perform a vacuum pumping process. When the vacuum degree reaches 4×10 -4 Pa, successively evaporate SiO 2 , Ta 3 O 5 onto the quartz glass substrate for 7 groups, control the evaporation rate at 0.4 nm / s, the thickness of each layer of SiO 2 is 63.21 nm, and the thickness of each layer of Ta 3 O 5 is 93.57 nm to form a DBR bottom reflection layer with a high reflectivity (>98%).

[0075] Step 2: Dissolve S-1-NEABr / Rac-NMABr : FABr: PbBr 2  = 2:1:1 in a mixed solvent of DMF and DMSO with a concentration of 1 mL to form a 0.5 mol L -1 perovskite precursor solution, where the ratio of DMF to DMSO is 1:4.

[0076] Step 3: Uniformly drop 50 μL of the perovskite precursor solution onto the DBR bottom reflection layer; Adjust the spin coating time of the spin coater to 60 s, control the spin coating speed at 5000 rpm / min, and drop chlorobenzene solution from the top small hole at the 45th s after starting the spin coating; Place the DBR bottom reflection layer coated with the perovskite precursor solution on a hot stage for annealing, anneal at 100 °C for 10 minutes, and process to form a 100-nm-thick perovskite light-emitting layer, that is, a gain medium in the form of a perovskite thin film.

[0077] Step 4: Weigh 10 - 200 mg of polymethyl methacrylate (PMMA) powder, dissolve it with chlorobenzene or toluene solvent for later use;

[0078] Step 5: Spin - coat a spacer layer of PMMA optical microcavity on the perovskite film to enhance the cavity length. The concentration of the PMMA solution is 220 mg / ml, the spin - coating speed is 5000 rpm, and after spin - coating, it is cured by heating on a hot stage at 120 °C for 10 min.

[0079] Step 6: Load the sample obtained in Step 4 into a thermal evaporation coating machine and perform vacuum pumping. When the vacuum degree reaches 5×10 -5 Pa, evaporate silver metal on the sample with a thickness of 320 nm to form a top reflective layer with a reflectivity > 99%. After waiting for the thermal evaporation to complete, take the device out of the evaporation chamber, and the laser is fabricated.

[0080] Place the fabricated device on an upright microscope stage. Focus the femtosecond laser with a wavelength of 343 nm onto the gain medium layer of the device through a 10X objective lens. Place a wheel - type attenuator in front of the laser to adjust the excitation intensity. Place a polarizer in front of the spectrometer detector and rotate the angle of the polarizer to measure the polarization of the generated laser beam. Figure 8 a in Figure 8 and b in are the photoluminescence spectra of quasi - two - dimensional perovskite films prepared based on chiral and achiral amines as a function of pump energy. For the thin - film sample based on chiral amine, under the excitation of ultraviolet light, as the pump energy increases, the amplified spontaneous emission signal peak gradually appears. Then, for the achiral thin film, it is always a fluorescence signal, indicating that its threshold is very high or it is difficult to achieve population inversion and thus the amplified spontaneous emission cannot occur. The law observed in this system is the same as that in Example 1. Other laser proof - testing steps are omitted, and mainly Example 1 is described in detail.

[0081] Those skilled in the art will readily conceive of other embodiments of the present application after considering the specification and practicing the content disclosed herein. The present application is intended to cover any variations, uses, or adaptations of the present application that follow the general principles of the present application and include known common knowledge or conventional technical means in the technical field not disclosed in the present application.

Claims

1. A room temperature continuous wave perovskite laser based on chiral amine ligands, comprising an optical microcavity, a gain medium, and a spacer layer, wherein the gain medium is sandwiched between the optical microcavity and the spacer layer, and a reflective layer is plated on the spacer layer, characterized in that: The gain medium is a mixed material including a perovskite material, which is uniformly distributed in the optical microcavity in the form of a thin film with a thickness of 10nm to 1mm. When the two-dimensional phase in the gain medium is excited with an energy higher than the band gap, the excitons in the valence band absorb energy and transition to the conduction band, and the high-energy hot excitons gradually cool to the band edge energy level through scattering collision and electroacoustic coupling. The components of the perovskite material are (S-Br-MBA)2FAPb2Br7, where S-Br-MBA is S-p-bromo-1-phenylethylamine; The mixed material includes one or more of organic small molecule materials, organic polymer materials, inorganic oxide materials, III-V materials, II-VI materials, rare earth materials, and perovskite materials; The optical microcavity type is a distributed Bragg reflector, a distributed feedback Bragg grating, a photonic crystal, a continuous bound state structure, a topological photonic crystal or a whispering gallery mode.

2. A method for preparing a room temperature continuous wave perovskite laser based on a chiral amine ligand, characterized in that: The method for preparing the room temperature continuous wave perovskite laser based on chiral amine ligand as claimed in claim 1 specifically comprises the following steps: preparing an optical microcavity as a bottom reflective layer; Preparation of a gain medium: dissolving a material having a molar ratio of S-Br-MBABr: FABr: PbBr2 = 2:1:2 in a solvent to obtain a perovskite precursor solution; spin coating or drop coating the perovskite precursor solution on a bottom reflective layer, annealing, and crystallizing to obtain a gain medium; Spin coating the polymer on the gain medium to form a spacer layer; The layer is vacuumed and a top reflection layer is formed on the spacer layer by thermal evaporation.

3. The method for preparing a room temperature continuous wave perovskite laser based on a chiral amine ligand according to claim 2, characterized in that: On quartz, sapphire or flexible substrate polyethylene terephthalate, a multilayer silicon dioxide / tantalum pentoxide dielectric layer is deposited by sputtering or electron beam evaporation to form a distributed Bragg reflector, i.e., a bottom reflection layer; the thickness of each dielectric film is λ / 4n, where λ is the central wavelength of the gain medium light emission and n is the refractive index of the dielectric layer material.

4. The method for preparing a room temperature continuous wave perovskite laser based on a chiral amine ligand according to claim 2, characterized in that: Before the perovskite precursor solution is spin-coated or drop-coated on the bottom reflective layer, the bottom reflective layer is subjected to oxygen plasma etching treatment.

5. The method for preparing a room temperature continuous wave perovskite laser based on a chiral amine ligand according to claim 2, characterized in that: 0.5 mol% molecular additives are also added to the perovskite precursor solution, and filtered through a polytetrafluoroethylene hydrophobic filter membrane, wherein the solvent is a mixture of any one or more of N,N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, and dimethylacetamide; and the molecular additives are a mixture of one or more of polymers, small molecules, and oxides.

6. The method for preparing a room temperature continuous wave perovskite laser based on a chiral amine ligand according to claim 2, characterized in that: When the polymer is spin-coated on the gain medium, the rotation speed is 2000-6000 rpm and the time is 30-60 s.

7. The method for preparing a room temperature continuous wave perovskite laser based on a chiral amine ligand according to claim 2, characterized in that: Vacuum treatment was performed. When the vacuum degree reached 5×10 -5 Pa, metallic silver is evaporated on the spacer layer as the top reflective layer.

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