Study On Electronic And Optical Properties Of Silver-copper Clusters As Dye Sensitizers

To solve the energy crisis and environmental pollution,China has put forward the proposal of“carbon peak”and“carbon neutralization”,focusing on clean energy such as solar energy.The solar cell is one of the main measures of massive-scale utilization of solar energy.Dye-sensitized solar cells have good application prospects because of their low cost,extensive materials,non-toxic,non-pollution,etc.At present,there are poor stability and low photoelectric conversion efficiency in dye-sensitized solar cells.In recent years,the Ag-Cu clusters are designed as sensitizers for dye-sensitized solar cells due to their excellent optical absorption.However,the current researches on the structural stability,electronic,and optical properties of the Ag-Cu clusters are not enough to apply them to practice.Therefore,it is necessary to further study the properties and applications of the Ag-Cu clusters.We first study the structure,electronic,and optical properties of the Ag-Cu clusters by using the first principle.Then,we prepared the Ag-Cu clusters sensitized solar cells and studied their photoelectric performance.The main conclusions are as follows:Firstly,the effects of composition changes on their structure,electronic,and optical properties of 9-atomAg-Cu clusters are investigated.The results show that in 9-atomAg-Cu clusters,the lowest energy structures of the Ag₈Cu₁,Ag₇Cu₂,Ag₂Cu₇,and Ag₁Cu₈clusters are similar to pure Ag₉cluster.They are all composed of two pentahedrons and one tetrahedron,and the shapes of other clusters are different from pure clusters.The Ag₅Cu₄and Ag₂Cu₇clusters are magic clusters,and the Ag₅Cu₄cluster shows the highest electronic stability.Compared with the Ag₉-? and Cu₉-? clusters,the optical absorption peaks of all clusters(except Ag₂Cu₇-? and Ag₁Cu₈-?)appear blue-shift.The Raman and infrared spectra of the Ag-Cu clusters provide some important vibration peaks,which can be used to determine the composition and structure of these clusters.Secondly,the effects of size changes on the structure,electronic,and optical properties of the Ag-Cu clusters with equal atomic ratios are studied.The results indicate that the stabilities of the Ag-Cu clusters are closely related to the formation of the icosahedral core.As n is 9,the structures of the Ag_nCu_nclusters begin to appear the icosahedral core.With the increase of the atomic numbers,the Ag-Cu clusters are easy to form the icosahedral core,and the Ag₁₀Cu₁₀clusters are more stable among these clusters.There are unpaired electrons in the electron spin-orbit of the Cu₁₆-? cluster,showing that the Cu₁₆-? cluster is magnetic.Through the research on the excited state spectrum,it is found that the absorption performance in the visible region of the Ag-Cu clusters is better than pure clusters.With the size increase,the absorption spectra of all clusters are red-shift.Finally,the properties of the Ag-Cu clusters and sensitized solar cells prepared with different proportions are studied.The results indicate that the light absorption intensity and range of the Ag-Cu clusters are better than pure Ag and Cu clusters.The photovoltaic performance of the Ag-Cu cluster sensitized solar cells shows that the photoelectric conversion efficiency and stability of the Ag-Cu clusters sensitized solar cells are significantly higher than pure Ag and Cu clusters sensitized solar cells.Among them,the Ag₁Cu₂cluster sensitized solar cells achieve good performance,with the open-circuit voltage of 515 mV,the short-circuit current density of 0.246 mA/cm²,the photoelectric conversion efficiency of 0.077%and shows good photocurrent stability.