Interfacial Property Regulation And Photoelectric Properties Of CsPbBr₃ Nanorod-Zinc Porphyrin Composites

Porphyrin molecules are highly conjugated macromolecular heterocyclic organic compounds composed of numerousπelectrons.Porphyrins and their derivatives have good light absorption,plane property and electron transport property.Porphyrins themselves can adjust their molecular properties by surface modification and changing the metal in the cavity,and because of their conjugated structure and good thermal stability,they can be used to manufacture photoelectric devices with excellent performance.However,although porphyrins have strong absorption in Q band,the absorption between Q band and Soret band is very small.The light in this band is the main part of the solar spectrum and the full use of the light in this band can effectively improve the efficiency of photoelectric conversion.It is an effective method to improve the efficiency of light capture by selecting the material with excellent optical properties as the"antenna"of light capture and combining with porphyrin.In order to improve the efficiency of light capture,the"antenna"must have efficient energy transfer ability to porphyrin.CsPbX₃ nanomaterial has the advantages of strong light absorption,high carrier mobility,adjustable luminescence,wide color gambit and high color purity.It has a good application prospect in solar cells,photoelectric detection,light-emitting diodes and other fields,and is an excellent"antenna"for light capture.However,CsPbX₃generally has long chain ligands such as oleic acid and oleamine on its surface.As the epitaxial structural layer of nanomaterials,it directly affects the surface properties of nanomaterials and the energy and material conversion process with the surrounding space,which is the key to the subsequent application problems.In recent years,researchers have been trying to design a stable and efficient energy transfer system to improve the photoelectric conversion performance of porphyrins.By replacing the surface ligand of"antenna",the stability and energy transfer efficiency can be improved,which is of great significance for the realization of efficient photoelectric conversion devices and one of the hot topics in the research.In this paper,the energy transfer between CsPbBr₃ nanords（NRs）and 2,3,7,8,12,13,17,18-octaethyl-21h,23H-Porphine zinc（II）（zinc porphyrin）improved the light capture effect of ZnP by CsPbBr₃ nanords（NRs）as light capture antenna.A variety of ligands（mercaptopropionic acid（MPA）,anthracic acid（ACA）,glutamic acid（GA）,succinic acid（SA））were used to replace the original long chain ligands of CsPbBr₃ NRs.Steady state fluorescence and fluorescence lifetime tests proved that the CsPbBr₃NRs with MPA as the ligand had efficient resonance energy transfer between ZnP and NRs.Photoelectric performance test further confirmed that MPA-NRs significantly improved the photoresponse characteristics of ZnP.The main research conclusions of this paper include:（1）CsPbBr₃ NRs with high quantum yield was directly synthesized by one-step ultrasonic assisted method.The diameter and length of CsPbBr₃ NRs were about 5 nm and 13 nm,and the size was uniform and the dispersion was good.The changes of absorption and fluorescence peaks of CsPbBr₃ NRs provide evidence of strong interaction between light and matter at different excitation powers.At the same time,this paper also studied the factors influencing the stability of CsPbBr₃ NRs.The results showed that compared with temperature,strong polar reagent had a more significant effect on the stability of CsPbBr₃NRs.（2）The fluorescence spectrum of donor CsPbBr₃ NRs overlapped with the absorption spectrum of recipient ZnP,theoretically satisfying the condition of energy transfer from CsPbBr₃ NRs to ZnP,which provided a theoretical basis for energy transfer from CsPbBr₃ NRs to ZnP.In this paper,the overlap of fluorescence spectrum of CsPbBr₃ NRs and absorption spectrum of ZnP reached 1.91×10^-12dm³mol^-1cm³by calculation,which provides theoretical support for the realization of energy transfer.（3）The fluorescence spectra of CsPbBr₃ NRs were analyzed by adding ZnP into toluene solution with a certain concentration of CsPbBr₃ NRs.The results showed that the fluorescence intensity of CsPbBr₃ NRs decreased with the increase of ZnP concentration,indicating that there was a strong interaction between CsPbBr₃ NRs and ZnP.The fluorescence lifetime of CsPbBr₃ NRs also showed that the fluorescence lifetime of CsPbBr₃ NRs decreased with the increase of ZnP.The above two points fully prove that the fluorescence resonance energy transfer is generated between CsPbBr₃ NRs and ZnP.The calculated energy transfer efficiency is above 50%,and the fluorescence quenching efficiency and energy transfer efficiency of CsPbBr₃ NRs are very close numerically.（4）A variety of ligands（succinic acid（SA）,anthracic acid（ACA）,mercaptopropionic acid（MPA）,glutamic acid（GA））were used for surface ligand replacement of toluene solution with the same concentration of CsPbBr₃ NRs.NRs with different surface ligands and different optical properties（SA-NRs,MPA-NRs,ACA-NRs,Ga-NRs）were obtained,and then ZnP was gradually added into toluene solution.The fluorescence and fluorescence lifetime were also measured and analyzed.The results showed that the fluorescence intensity and fluorescence lifetime decreased with the increase of ZnP,and there was more efficient energy transfer between single MPA-NRs and ZnP,and the energy transfer efficiency reached more than 60%.（5）ZnP,CsPbBr₃ NRs,NRs of different ligands and different NRs and ZnP composite optoelectronic devices were prepared,and the photoelectric properties were tested.The results show that when the illumination output power is 150 m W/cm² and the illumination band is 420-780 nm,photoelectric conversion effect of MPA-NRs and ZnP composites is better than other composites.When the incident light source is 458 nm monochromatic light,the MPA-NRs+ZnP composite optoelectronic device with the concentration of 5×10^-5mo L/L ZnP has good light response characteristics.Further analysis results show that the photocurrent intensity of the device increases with the increase of power,and the relationship between the two is linear,which proves the good photoelectric response characteristics of the device.In this paper,CsPbBr₃ NRs is first used as the"antenna"of light capture,and the energy transfer between NRs and ZnP is used to increase the light capture effect of ZnP,thus improving the light response characteristics of ZnP device.Then,the surface ligands of CsPbBr₃ were replaced by a variety of ligands.Through fluorescence spectrum and fluorescence lifetime,it was proved that the fluorescence resonance energy transfer efficiency between CsPbBr₃ and ZnP could reach 60%after mercaptopropionic acid（MPA）replaced the surface ligands of CsPbBr3 NRs.At the same time,compared with the single ZnP photodetector,the composite structure of CsPbBr₃ NRs and ZnP shows higher photocurrent,larger switching ratio and other advantages.The composite structure of ZnP and CsPbBr₃ NRs after replacement ligand also brings new thinking to the research of visible light photoelectric technology.