Research method of AuCu14 photoluminescence mechanism

Abstract

The invention relates to the technical field of photoluminescence material research, in particular to a research method of an AuCu14 photoluminescence mechanism. An AuCu14 cluster, an AgCu14 cluster and a Cu14Au cluster are constructed, ground state structure optimization is carried out on the three clusters, excited state structure optimization is carried out on the basis of ground state optimization, charge transfer analysis is carried out on the three clusters, electron-hole analysis is carried out on the process from T1 to S0 in the aspect of configuration, optical property research is carried out, and the method has the advantages that the method is simple and easy to implement, and the application prospect is wide. And calculating a spin-orbit coupling constant and a wavelength, and explaining the reason of the high phosphorescence quantum yield. According to the invention, the research on the light-emitting mechanism of the AuCu14 cluster is developed, a theoretical support is provided for the research on the light-emitting mechanism of the AuCu14 cluster, the most important influence factor that the spin-orbit coupling constant is the light-emitting of the AuCu14 cluster is explored, and a theoretical guidance is provided for exploring mechanism light-emitting methods of other clusters.

Description

Technical Field

[0001] The present invention belongs to the technical field of photoluminescent material research, and specifically relates to an AuCu 14 Methods for studying the mechanism of photoluminescence. Background Art

[0002] Metal clusters have good physical properties, especially their photoluminescence properties. Compared with organic dyes and semiconductor quantum dots, metal nanoclusters have better biocompatibility, photostability and lower toxicity, so they have important applications in optical sensing and biomedicine. However, the luminescence quantum yield of metal nanoclusters is very low, generally around 20%. In recent years, people have been committed to synthesizing metal clusters with high quantum efficiency.

[0003] 2022Song Y, Li Y, Zhou M, et al.Ultrabright Au@Cu 14 nanoclusters: 71.3% phosphorescence quantum yield in non-degassed solution at room temperature[J]. Science advances, 2021, 7(2): eabd2091. et al. synthesized [AuCu 14 (SR) 12 (BCPP)6] + Cluster, AuCu 14 The clusters have a luminescence quantum yield of up to 74% and have important applications in OLEDs, but the theoretical mechanism of their luminescence mechanism and the reasons for their high quantum efficiency have not been theoretically studied. Theoretical calculations of the photoluminescence mechanism play an indispensable role in promoting the development of luminescent material science. It not only deepens our understanding of luminescence phenomena, but also provides a powerful tool for the design and application of new materials. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, the present invention provides an AuCu 14 The research method of photoluminescence mechanism, the present invention develops AuCu 14 The luminescence mechanism of AuCu 14 The study of the luminescence mechanism of the cluster provides theoretical support, and the spin-orbit coupling constant is found to be AuCu 14 The most important influencing factor of cluster luminescence provides theoretical guidance for exploring the luminescence mechanism of other clusters.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] AuCu 14 The method for studying the photoluminescence mechanism comprises the following steps:

[0007] In [AuCu 14 (SR) 12 (BCPP)6] + Based on this, Gaussianview was used to construct the AuCu 14 Clusters, Cu 14 Au clusters and AgCu 14 The structure of the clusters, using the PBE0 / def2svp basis set to perform ground state structure optimization and frequency vibration analysis on the three clusters until it is confirmed that the structure has no imaginary frequency, and three clusters with stable ground state structures are obtained, that is, the optimized ground state is obtained. The optimization of the ground state allows it to reach the lowest energy point, that is, the most stable state;

[0008] The orbital composition analysis program and state density analysis program in Multiwfn were used to obtain the AuCu 14 Clusters, AgCu 14 Clusters and Cu 14 The orbital composition and state density of Au clusters. The orbital composition analysis is used to discuss the electronic structure and analyze the charge transfer. The state density analysis can clearly and intuitively discuss the electronic structure of the system. The orbital localization program in Multiwfn is used to optimize the AuCu 14 Clusters, AgCu 14 Clusters and Cu 14 The electron localization analysis of Au clusters can well display the key electronic structure characteristics in the system through visualization, which is very helpful for analyzing bonding and electronic structure;

[0009] The electronic excitation analysis program in Multiwfn was used to obtain the AuCu 14 Clusters, AgCu 14 Clusters and Cu 14 The ultraviolet transition orbits of Au clusters, the ultraviolet corresponds to the orbital transitions at the absorption wavelength, to study which orbital transitions contribute to the ultraviolet absorption peak;

[0010] Multiwfn was used to perform electron-hole analysis on the excitation mode of the structure after TDDFT calculation. The distribution of "holes" perfectly describes the running path of excited electrons, while the distribution of "electrons" perfectly describes the destination of excited electrons, analyzing the process of photon excitation from the ground state to the excited state.

[0011] After determining the excitation modes of the three clusters, the IFCT program in Multiwfn was used to perform excited state charge transfer calculations and analysis to examine how electrons are transferred between any two fragments of the system during the electronic excitation process;

[0012] PBE0 / def2svp is used to optimize the excited state structure. The optimization of the excited state is based on the optimization of the ground state structure. The optimization of the excited state is to further analyze the electronic transition and reaction mechanism in the light reaction emission process, and obtain the optimized excited state. The optimized excited state is a triplet state.

[0013] For the three optimized excited state cluster configurations, electron-hole analysis was performed on the T1→S0 process in order to analyze the electron excitation mode during the emission process and understand the reasons for its optical properties;

[0014] Charge transfer analysis was performed on the three clusters in the optimized excited state to analyze the process of photons from the excited state to the ground state;

[0015] The optical properties of the three clusters in the excited state after optimization were studied to explain the electron transition mechanism in the emission process and explore how the ligands, structures and core metal atoms affect their optical properties through microscopic electronic structures;

[0016] The spin-orbit coupling constant and wavelength of the three clusters in the excited state after optimization were calculated. Spin-orbit coupling is crucial for phosphorescence, because the transition dipole moment between the triplet state and the singlet state is 0, which is a forbidden transition; the coupling of spin angular momentum and orbital angular momentum allows the transition dipole moment to be non-zero, so that the transition between the triplet state and the singlet state is no longer a forbidden transition. The larger the spin-orbit coupling constant, the faster the rate of photons from S1→T1. Therefore, the calculation of spin-orbit coupling can explain the reason for the high phosphorescence quantum yield. The calculation of theoretical wavelength can be used to predict and design new materials with specific emission wavelengths, which has important guiding significance for the development of new luminescent materials and fluorescent probes.

[0017] Preferably, the TDDFT method is used to optimize the AuCu 14 Clusters, AgCu 14 Clusters and Cu 14 The UV spectrum of Au clusters was calculated to confirm that the theoretical calculation of the UV spectrum is consistent with the experimental calculation. 14 (SR) 12 (BCPP)6] + The excited state of the cluster is difficult to calculate. The phenyl group on the experimentally synthesized cluster P ligand was replaced with a methyl group to obtain a simplified methyl ground state. The simplified methyl ground state was taken as the research object, and the excited state structure was optimized based on the simplified methyl ground state to analyze the electron transition and reaction mechanism in the photoreaction emission process.

[0018] Preferably, the method for performing electron-hole analysis on the process T1→S0 is: hole-electron analysis is a very powerful and extremely practical method for examining the characteristics of electron excitation supported by the Multiwfn program. It describes the electron excitation process as "hole→electron", thereby graphically and intuitively examining where the electrons leave and where they go, whether it is local excitation, overall excitation, electron transfer excitation or excitation of hybrid characteristics.

[0019] Preferably, the excited state of AuCu is optimized 14 Clusters, AgCu 14 Clusters and Cu 14 The charge transfer analysis method for Au clusters is as follows: the optimized triplet state is imported into the electronic excitation analysis module, and the three clusters are divided into five fragments: core atoms, first-layer Cu cages, second-layer Cu cages, external S-based ligands, and external P-based ligands for charge transfer analysis.

[0020] Preferably, the excited state of AuCu is optimized 14 Clusters, AgCu 14 Clusters and Cu 14 The method for studying the optical properties of Au clusters is: electron-hole analysis, charge transfer analysis and energy wavelength calculation of the three clusters.

[0021] Preferably, the excited state of AuCu is optimized 14 Clusters, AgCu 14 Clusters and Cu 14 The calculation method of the spin-orbit coupling constant of the Au cluster is: extract the optimized ground state structure coordinates, use the PBE0 functional in the quantitative software orca, and the DKH2 basis set to calculate the spin-orbit coupling constant between the singlet state and the triplet state of the three clusters. The spin-orbit coupling constant is very important for the phosphorescence process, and its size affects the quantum yield of phosphorescence. Molecules containing heavy atoms usually have a large spin-orbit coupling, which can enhance the efficiency of phosphorescence. Through calculation, we study the influence of heavy atoms on phosphorescence properties. We hope to be able to theoretically predict clusters with high phosphorescence quantum yields by comparing the size of the spin-orbit coupling constant.

[0022] Preferably, the calculation method of the wavelengths of the three clusters in the excited state after optimization is as follows: after optimizing the excited state structure, the wavelength is given using the output file of Gaussian16.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. In-depth understanding of the luminescence mechanism: Theoretical calculations can help scientists deeply understand the physical process of photoluminescence, including electronic transitions, excited state dynamics, energy transfer and non-radiative relaxation. For example, calculations can reveal the mechanism of restricted intramolecular motion (RIM) of aggregation-induced emission (AIE) molecules in the aggregated state and how it affects the luminescence efficiency.

[0025] 2. Predict and design new luminescent materials: Theoretical calculations can predict the photoelectric properties of new luminescent materials and guide experimental design and synthesis. For example, calculations can predict the fluorescence quantum efficiency of different molecular structures, thereby designing new materials with higher luminescence efficiency.

[0026] 3. Optimizing material performance: Theoretical calculations can be used to optimize the performance of existing luminescent materials, such as improving luminous efficiency, adjusting luminous color, and enhancing stability. Calculations can also be used to discover bottlenecks in material performance and propose improvement strategies.

[0027] 4. Explore new luminescence mechanisms: Theoretical calculations help explore and verify new luminescence mechanisms, such as upconversion luminescence and thermally activated delayed fluorescence (TADF). The discovery and understanding of these new mechanisms can promote innovative development in the field of luminescent materials.

[0028] 5. Interdisciplinary application: Theoretical calculations of photoluminescence mechanisms not only have important applications in the field of materials science, but can also be cross-integrated with other disciplines such as biology, medicine, and environmental science to promote research progress in related fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 In (a), [AuCu 14 (SR) 12 (BCPP)6] + The actual UV absorption spectrum of the cluster, (b) is [AuCu 14 (SR) 12 (BCPP)6] + Theoretical UV absorption spectrum of the cluster;

[0030] Figure 2 The AuCu constructed using Gaussianview in Example 1 14 Clusters, AgCu 14 Clusters and Cu 14 Schematic diagram of the structure of Au clusters;

[0031] Figure 3 The above figure shows the AuCu in Example 1. 14 Theoretically calculated UV absorption diagram of the cluster, and the figure below is the ks orbital energy level diagram;

[0032] Figure 4The figure above is the AgCu in Example 1 14 Theoretically calculated UV absorption diagram of the cluster, and the figure below is the ks orbital energy level diagram;

[0033] Figure 5 The above figure shows Cu in Example 1. 14 Theoretical calculation of the UV absorption of Au clusters. The figure below shows the ks orbital energy level.

[0034] Figure 6 is the AuCu in Example 1 14 Clusters, AgCu 14 Clusters and Cu 14 Theoretical calculation of the density of states of Au clusters;

[0035] Figure 7 is the AuCu in Example 1 14 Clusters, AgCu 14 Clusters and Cu 14 The electron localization analysis diagram of the YZ plane of Au cluster;

[0036] Figure 8 is the AuCu in Example 1 14 Transition molecular orbital diagram of the cluster at 297nm, 345nm, and 408nm of the UV absorption spectrum;

[0037] Fig. 9 is the AgCu in Example 1 14 Transition molecular orbital diagram of the cluster at 378nm, 419nm, and 505nm of the UV absorption spectrum;

[0038] Fig.10 is Cu in Example 1 14 Transition molecular orbital diagram of Au clusters at 375nm, 422nm and 480nm of UV absorption spectrum;

[0039] Fig.11 is the AuCu in the excitation process in Example 1 14 Clusters, AgCu 14 Clusters and Cu 14 Electron-hole analysis of Au clusters;

[0040] Fig.12 is AuCu in the emission process in Example 1 14 Clusters, AgCu 14 Clusters and Cu 14 Electron-hole analysis of Au clusters;

[0041] Fig.13 is AuCu in the emission process in Example 1 14 Clusters, AgCu 14 Clusters and Cu14 Heat map of atomic contributions of Au clusters. DETAILED DESCRIPTION

[0042] The specific embodiments of the present invention are described in detail below, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention. The experimental methods described in the embodiments of the present invention are conventional methods unless otherwise specified.

[0043] The following experimental methods and detection methods, unless otherwise specified, are conventional methods; the following reagents and raw materials, unless otherwise specified, are commercially available.

[0044] Example 1

[0045] AuCu 14 The method for studying the photoluminescence mechanism comprises the following steps:

[0046] S1. Calculation of UV spectra using TDDFT method

[0047] First, we used the TDDFT method to analyze the experimentally synthesized [AuCu 14 (SR) 12 (BCPP)6] + Clusters (hereinafter referred to as Cu 14 ben) calculated the theoretical spectrum, such as Figure 1 As shown, we found that the theoretical UV spectrum is highly consistent with the experiment, thus verifying the reliability of the theoretical calculation.

[0048] Considering [AuCu 14 (SR) 12 (BCPP)6] + The excited state of the cluster is difficult to calculate. To simplify the calculation, and considering that both methyl and phenyl groups are weak electron-donating groups with similar electron-donating abilities, we replaced the phenyl group on the experimentally synthesized cluster P ligand with a methyl group. We discussed the effects of core doping and structural changes on its optical properties after replacing the ligand.

[0049] S2. Use Gaussianview to 14 (SR) 12 (BCPP)6] + AuCu clusters 14 Clusters, AgCu 14 Clusters and Cu 14 Au cluster structure, AuCu in this example 14 The cluster is [AuCu14 (SR) 12 (BCPP)6] + The phenyl group of the cluster is replaced by a methyl group, e.g. Figure 2 As shown, AuCu 14 The cluster is composed of Au atoms as the core and 8 Cu atoms forming a cube. The Cu8 cage forms the first shell layer, and the Cu atoms at the center of the Cu8 cage form the Cu6 cage, which is the second shell layer. The Cu8 is connected to the s atom, and the Cu6 is connected to the neutral p group to form a rigid structure. 14 The Au cluster is just the opposite, with the central Au atom as the core, the Cu6 cage as the first shell, and the outer second shell as the Cu8 cubic cage. The Cu atoms are tightly connected by s atoms and p atoms. 14 Core doping with Ag atoms to form AgCu 14 Clusters.

[0050] S3, using the PBE0 / def2svp basis set to analyze AuCu 14 Clusters, AgCu 14 Clusters and Cu 14 The Au cluster was subjected to structural optimization and frequency vibration analysis, confirming that the structure had no imaginary frequencies, indicating that it had reached the most stable state and obtained an optimized ground state.

[0051] S4, orbital composition, density of states (DOS) and electron localization analysis (ELF)

[0052] The orbital composition analysis program and state density analysis program in Multiwfn were used to obtain the orbital composition and state density of the three clusters, and the orbital localization program in Multiwfn was used to perform electron localization analysis on the three clusters. The results are as follows Figure 3-5 As shown, in the optimized ground state, AuCu 14 The HOMO orbital of the cluster is mainly composed of the d orbitals of Au atoms and Cu atoms, and the LUMO orbital is mainly composed of the sp orbitals of Au and Cu. 14 The HOMO orbital of Ag is mainly contributed by Ag atoms, and the LUMO orbital is mainly composed of the sp orbitals of Ag and Cu. 14 In the HOMO orbital of Au, the d orbital of Cu occupies a larger proportion than the first two.

[0053] After the core is doped with Ag, H-Lgap decreases, and after changing its structure, H-Lgap also decreases, indicating that changes in structure and core atoms have a significant impact on their orbital components. From the ELF image, we can see that the Cu atoms of the three clusters are highly delocalized near the core atoms. Figure 6It can also be seen from the DOS diagram that when it is close to -7ev, Cu(d) contributes the most to the total state density, and the M(d) orbital is hybridized with the sp orbital. Therefore, it is determined that there is a very strong electronic force between the core Au atom and the surrounding Cu cage, which also leads to the AuCu 14 The structure has strong rigidity.

[0054] Figure 7 The results show that there is bonding between the P and S atoms and their connected methyl groups, but the core metal cages of the three clusters are highly electronically delocalized, indicating strong interactions between the core metals.

[0055] like Figure 8-10 As shown in Figure 2, we found that after replacing the phenyl group on the p-ligand with a methyl group, AuCu 14 The positions of the UV absorption peaks were significantly blue-shifted at 297nm, 345nm and 408nm. 14 There is strong absorption at 378nm, 419nm, and 505nm. After the central atom is doped, the position of the ultraviolet peak undergoes a significant red shift. 14 The Au clusters absorb at 375nm, 422nm and 480nm respectively.

[0056] S6. Computational analysis of ultraviolet transition orbits

[0057] We further used the electronic excitation analysis program in Multiwfn to study the AuCu 14 Clusters, AgCu 14 Clusters and Cu 14 The orbital transitions corresponding to the absorption peaks of the three types of Au clusters' UV spectra are as follows: Figure 8-10 As shown, AuCu 14 The cluster mainly transitions from H-6 to L+3 at 297nm, and the electron density is transferred from the ligand S group to the P group, which corresponds to LLCT. At 345nm, the main transitions occur from H-4 to L+1 and from H-3 to LUMO. The transition from HOMO to LUMO at 408nm is a core transition, which corresponds to MMCT. 14 At 378nm, the main orbital transitions occurred were from H-5 to L and from H to L+4, corresponding to LMCT and MLCT, respectively, and at 505nm, it was also MMCT. 14 Au mainly undergoes LMCT at 375nm, and transitions from HOMO to LUMO at 480nm, which is manifested as a transition of the metal core.

[0058] S7. Electron-hole analysis during excitation

[0059] To further explore the optical properties, we used Multiwfn to perform electron-hole analysis on the excitation modes of the structure calculated by TDDFT. The distribution of "holes" perfectly describes the path of excited electrons, while the distribution of "electrons" perfectly describes the destination of excited electrons. Sr represents the overlap between holes and electrons, and D represents the distance between the center of mass of holes and electrons. Fig.11 As shown, we see AuCu 14 and AgCu 14 The electron-hole overlap is large, both at 73%, and the distance between the hole and the electron center is very small, which again shows that they are LE (local excitation), while Cu 14 The Au cluster is different from the previous two. The overlap between holes and electrons is moderate, and the center distance between holes and electrons is 1.286 angstroms. It is dominated by LE (local excitation) and accompanied by CT (charge transfer excitation).

[0060] S8. Excited state charge transfer (IFCT) calculation analysis

[0061] Determined AuCu 14 Clusters, AgCu 14 Clusters and Cu 14 We further performed IFCT charge transfer analysis on the excitation modes of the three Au clusters. Core represents the core atom, Shell 1 and Shell 2 represent the first shell and the second shell, respectively, and R1 and R2 represent the external S-based ligand and P-based ligand, respectively. From Table 1, we can see that when the AuCu 14 Only Cu8 transfers 0.02 electrons to the Au core, and the main electron transfer occurs from the Cu8 cage to the S-based ligand. 14 Less electron transfer occurs in AuCu 14 The difference is that a small amount of electron transfer occurs from the P group to the S group. 14 Au underwent a reverse electron transfer of 0.028 from the S group to the core Au atom, indicating that changing its structure has an impact on the electron transfer during the excitation process.

[0062] Table 1AuCu 14 Clusters, AgCu 14 Clusters and Cu 14 Excitation mode table of Au clusters

[0063]

[0064]

[0065] S9. Use PBE0 / def2svp to optimize the excited state structure based on the optimized ground state: put the optimized ground state structure into Gaussianview, extract the structural coordinate information, use the TDDFT method and the same functional basis set, and use Gaussian16 software to calculate the excited state structure.

[0066] S10, Electron-hole analysis of the T1→S0 process on the optimized excited state configuration

[0067] After optimizing the excited state structure, we used Multiwfn to perform electron-hole analysis on its emission mode, such as Fig.12 As shown, we see AuCu 14 and AgCu 14 The electron and hole density overlap is very large, which is a typical LE emission mode, while Cu 14 The hole-electron center-of-mass distance of Au is 1.7 Å, which is much larger than the former, corresponding to the HLCT (mixed LE and CT) emission mode, which is also consistent with the previous excitation mode. Therefore, for phosphorescence, a larger electron-hole overlap is better, that is, LE is more conducive to phosphorescence emission.

[0068] S11. Charge transfer analysis based on optimized excited state structure

[0069] We further studied the charge transfer during the emission process. The analysis method was as follows: the triplet structure was imported into the electronic excitation analysis module, and the three clusters were divided into five fragments: core atoms, first-layer Cu cages, second-layer Cu cages, external S-based ligands, and external P-based ligands for charge transfer analysis. The results are shown in Table 2. 14 In the process from cluster T1 to S0, the excited state charge transfer is less, and in AgCu 14 In the cluster, the main thing that happens is the transfer of Ag core to Cu8 cage, which is about 0.2. 14 The main charge transfer that occurs in the Au cluster is from the S base to the Cu8 cage. In contrast, the charge transfer from the Cu8 and Cu6 cages to the metal core occurs. From the above, we can see that doping significantly increases the charge transfer from the Cu cage to the metal core, changes the structural configuration, and causes a reverse charge transfer from the core to the Cu cage, thereby changing the different optical properties of the three clusters.

[0070] Table 2AuCu 14 Clusters, AgCu 14 Clusters and Cu 14 Charge transfer table during Au cluster emission

[0071] IFCT Aucu14 Agcu14 Cu14Au T1-S0 T1-S0 T1-S0 Core→Shell1 0.006 0.28 -0.01 Core→Shell2 0.00 0.004 -0.013 Core→R1 0.002 0.017 -0.02 Core→R2 0.00 0.003 -0.008 Shell1 → Shell2 -0.003 0.002 -0.03 Shell1→R1 -0.006 -0.006 -0.04 Shell1→R2 0.00 0.00 -0.02 Shell2→R1 0.002 -0.002 0.004 Shell2 → R2 0.00 0.00 -0.007 R1→R2 0.00 0.00 -0.01

[0072] S12. Heat map of atomic contributions during emission

[0073] In order to further understand the influence of core atoms on their optical properties, electron-hole analysis, charge transfer analysis and energy wavelength calculation were performed on the three clusters. We also performed heat map analysis on them. The results are as follows: Fig.13 As shown. 14 The Au atom number in the cluster is 1, the Cu atoms are 2-8, 18-24, and the AgCu 14 The atomic number of Ag in the cluster is 153, Cu is 1-7, 17-23, Cu 14 The atomic number of Au in Au is 21, and that of Cu is 22-27, 28-35. 14 During the emission process, the core Au atoms account for up to 15% of their electrons and holes; 14 In the case of Cu, the core Ag atoms contribute 18% to holes and 13% to electrons. 14 The electrons and holes in the Au emission process are mainly contributed by the core Au atoms and Cu atoms. The core metal atoms of the three clusters contribute greatly to the electron-hole emission process, indicating that their core atoms are highly involved in the emission process, resulting in high phosphorescence quantum efficiency.

[0074] S13. Calculate the spin-orbit coupling constant (SOC) and wavelength

[0075] The optimized ground state structure coordinates were extracted, and the PBE0 functional and DKH2 basis set were used in the quantitative software orca to calculate the spin-orbit coupling constants between the singlet state and the triplet state of the three clusters. 14 The high yield of ben is due to the fact that the core Au atoms greatly enhance the S1→T1 spin-orbit coupling constant (SOC). 14 Clusters, AgCu 14 Clusters, Cu 14 Au clusters and Cu 14 SOC of four clusters of ben cluster. As shown in Table 3, after replacing the benzene on the P and S groups with methyl groups, the SOC constant between S1→T1 increased significantly, and after doping the core Ag, the SOC decreased to 10.1, while the SOC constant of Au atoms is the largest among transition metal atoms, which once again proves that the core Au atoms can greatly increase the SOC of the structure. After changing its structure, the SOC also decreased to 15.7, indicating that AuCu 14 The unique rigid structure of the nanostructured carbon also affects its optical properties.

[0076] Table 3AuCu 14 Clusters, AgCu 14 Clusters, Cu14 Au clusters and Cu 14 SOC table of ben cluster

[0077] <![CDATA[SOC(cm -1 )]]> S1→T1 S2→T1 S3→T1 S1→T2 S2→T2 S3→T2 <![CDATA[AuCu 14 ]]> 137.8 1327.5 1327.1 1327.3 85.1 1331.2 <![CDATA[AgCu 14 ]]> 10.1 81.1 151.0 170.8 17.0 11.4 <![CDATA[Cu 14 To]]> 15.7 631.0 307.6 992.3 54 263.0 <![CDATA[Cu 14 ben]]> 54.3 1175.4 1123.2 1171 40 1134.4

[0078] We further calculated the AuCu 14 Clusters, AgCu 14 Clusters and Cu 14 The singlet-triplet energy gap and wavelength of the three Au clusters are shown in Table 4. When the phenyl group is replaced by the methyl group, the emission wavelength is 705 nm, which is a small red shift of about 18 nm. The emission wavelength after doping with Ag is 1101 nm, which is a large red shift. At the same time, the emission wavelength also undergoes a significant red shift when the structure is changed. 14 The single-triplet gap of the cluster is 0.69ev, which increases to 1.1ev after doping. The smaller single-triplet gap is beneficial to the inter-gap crossing of S1-T1, thereby improving the phosphorescence quantum yield. Therefore, after doping with Ag, the decrease in its soc constant and the increase in the single-triplet gap will hinder the inter-gap crossing rate of S1-T1, and theoretically reduce its luminescence quantum yield, which is unfavorable. We also calculated the soc of its initial structure after doping with Pt, Ir and Pb, intending to try to improve the quantum yield theoretically. Unfortunately, its structure was severely deformed during optimization. We calculated the SOC of replacing the Cu cage with the Au cage and the Ag cage. Unfortunately, their SOCs were relatively small and no further research was conducted on them.

[0079] Table 4AuCu 14 Clusters, Cu 14 Au clusters and AgCu 14 Table of singlet-triplet energy gap and wavelength of clusters

[0080] NC <![CDATA[ΔE S1 (this)]]> <![CDATA[F S1 ]]> <![CDATA[ΔE T1 (this)]]> <![CDATA[ΔE ST (this)]]> λ(nm) <![CDATA[AuCu 14 ]]> 2.12 0.22 1.427 0.693 868.8 <![CDATA[AgCu 14 ]]> 2.141 0.314 0.968 1.173 1279.3 <![CDATA[Cu 14 To]]> 1.307 0.015 0.859 0.448 1442.9

[0081] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and variations. The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and their protection scope is not limited thereto. Equivalent substitutions or changes made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention, and the protection scope of the present invention shall be subject to the claims.

Claims

1. AuCu 14 A method for studying the mechanism of photoluminescence, characterized in that: The steps include: In [AuCu 14 (SR) 12 (BCPP)6] + Based on the AuCu 14 Clusters, AgCu 14 Clusters and Cu 14 The structure of Au clusters, the ground state structure optimization and frequency vibration analysis of the three clusters were performed to obtain three clusters with stable ground state structures, that is, to obtain the optimized ground state structure; After optimizing the ground state, AuCu 14 Clusters, AgCu 14 Clusters and Cu 14 The orbital composition analysis, state density analysis and electron localization analysis of Au clusters were performed to obtain the electronic structure and charge transfer of the three clusters; After obtaining the optimized ground state, AuCu 14 Clusters, AgCu 14 Clusters and Cu 14 UV transition orbits of Au clusters; After optimizing the ground state, AuCu 14 Clusters, AgCu 14 Clusters and Cu 14 The excitation modes of Au clusters were analyzed by electron-hole analysis. After the excitation modes of the three clusters were determined, the excited state charge transfer calculation analysis was performed to examine the transfer of electrons during the electron excitation process. On the basis of optimizing the ground state, the excited state structure is optimized to obtain the optimized excited state, which is a triplet state, so as to analyze the electronic transition and reaction mechanism in the light emission process; After optimization, the excited state of AuCu 14 Clusters, AgCu 14 Clusters and Cu 14 Au cluster configuration, electron-hole analysis of the T1→S0 process, and the optimized excited state of AuCu 14 Clusters, AgCu 14 Clusters and Cu 14 Au clusters were subjected to charge transfer analysis to analyze the electronic excitation mode during emission; After optimizing the excited state of AuCu 14 Clusters, AgCu 14 Clusters and Cu 14 The optical properties of Au clusters were studied to analyze the process of photons from excited state to ground state; The spin-orbit coupling constants and wavelengths of the optimized excited states of the three clusters are calculated to explain the high phosphorescence quantum yield.

2. The AuCu according to claim 1 14 A method for studying the mechanism of photoluminescence, characterized in that: Considering [AuCu 14 (SR) 12 (BCPP)6] + There are too many atoms in the cluster and the excited state is difficult to calculate. 14 (SR) 12 (BCPP)6] + The phenyl group on the P ligand in the cluster was replaced by a methyl group to obtain AuCu 14 The structure of the cluster is based on AuCu 14 Clusters, AgCu 14 Clusters and Cu 14 Au clusters are taken as the research object. The ground state is optimized first, and then the excited state structure is optimized to analyze the electronic transition and reaction mechanism during the photoreaction emission process.

3. The AuCu according to claim 2 14 A method for studying the mechanism of photoluminescence, characterized in that: For [AuCu 14 (SR) 12 (BCPP)6] + The UV spectrum of the cluster was theoretically calculated using the TDDFT method. After confirming that the theoretical calculation was consistent with the experimental calculation, the [AuCu 14 (SR) 12 (BCPP)6] + The phenyl group on the P ligand in the cluster is replaced by a methyl group.

4. The AuCu according to claim 1 14 A method for studying the mechanism of photoluminescence, characterized in that: AU 14 Clusters, AgCu 14 Clusters and Cu 14 Au clusters were constructed using Gaussianview.

5. The AuCu according to claim 1 14 A method for studying the mechanism of photoluminescence, characterized in that: The orbital composition analysis program, state density analysis program and electron localization analysis in Multiwfn were used to obtain the AuCu 14 Clusters, AgCu 14 Clusters and Cu 14 The orbital composition, state density and electronic localization characteristics of Au clusters were obtained by using the electronic excitation analysis program in Multiwfn to optimize the AuCu 14 Clusters, AgCu 14 Clusters and Cu 14 Ultraviolet transition orbits of Au clusters.

6. The AuCu according to claim 1 14 A method for studying the mechanism of photoluminescence, characterized in that: The excitation mode was analyzed by electron-hole using Multiwfn, and the T1→S0 emission process was analyzed by Multiwfn.

7. The AuCu according to claim 1 14 A method for studying the mechanism of photoluminescence, characterized in that: Optimized excited state AuCu 14 Clusters, AgCu 14 Clusters and Cu 14 The charge transfer analysis method of Au clusters is as follows: the triplet structure is imported into the electronic excitation analysis module, and the three clusters are divided into five fragments: core atoms, first-layer Cu cages, second-layer Cu cages, external S-based ligands, and external P-based ligands for charge transfer analysis.

8. The AuCu according to claim 1 14 A method for studying the mechanism of photoluminescence, characterized in that: Optimized excited state of AuCu 14 Clusters, AgCu 14 Clusters and Cu 14 The method for studying the optical properties of Au clusters is: electron-hole analysis, charge transfer analysis and energy wavelength calculation of the three clusters.

9. The AuCu according to claim 1 14 A method for studying the mechanism of photoluminescence, characterized in that: Optimized excited state AuCu 14 Clusters, AgCu 14 Clusters and Cu 14 The calculation method of the Au cluster spin-orbit coupling constant is as follows: extract the optimized ground state structure coordinates, use the PBE0 functional in the quantification software orca, and the DKH2 basis set to calculate the spin-orbit coupling constants between the singlet state and the triplet state of the three clusters.

10. The AuCu according to claim 1 14 A method for studying the mechanism of photoluminescence, characterized in that: The calculation method of the wavelengths of the three clusters after optimizing the excited state is as follows: after optimizing the excited state, the output file of Gaussian16 is used to give the wavelength.

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