Structural Design And Optimization Of Optical Frequency Nano-rectenna

As one of the solar energy collection methods,the optical frequency nano-rectenna has a wider absorption spectrum and higher theoretical photoelectric conversion efficiency than traditional solar energy collection methods,so it has important theoretical research significance and broad industrial development prospects.The entire antenna system includes a receiving antenna and a rectifier.First,the optical nano-antenna is used to collect sunlight,and then the alternating current is converted into direct current through the tunneling rectifier diode to supply the load.In this paper,starting from the metal nano-antenna,a highly efficient conversion optical frequency nano-rectenna is designed,and it is processed,tested and optimized.The main research results are as follows:1.Taking metal materials as the object,a double-layer orthogonal nano-bow tie rectenna structure for receiving sunlight in different polarization directions was designed and optimized.First,based on the optical simulation software FDTD solution,a nano-bow-tie antenna unit with a wavelength of 400nm～1600nm was designed and simulated,and the influence of the four core parameters of the bow-tie tip distance,bow-tie angle,single-layer bow-tie thickness and medium on the total radiation efficiency of the antenna was analyzed.The overall structure parameters of the antenna are determined,and through simulation analysis,the total radiation efficiency of the antenna in vacuum is obtained as73.38%.Secondly,by mounting a rectifier diode made of Ag-Si O₂-Au on the double-layer orthogonal nano-bow tie antenna,the maximum current density on the secondary electrode after rectification is 4.728×10⁴A/m².2.In view of the difficulty in processing and preparation of nano-bow tie rectennas,this thesis takes non-metallic materials as the object to design and optimize multi-wall carbon nanotube rectennas that are easy to process and prepare,and are easy to commercialize.First,based on the particularity of the carbon nanotube material,the basic parameters of the material are equivalent,and the electromagnetic simulation software CST is used to design and simulate carbon nanotube antenna elements and arrays with a wavelength of400nm～1600nm.Through simulation analysis,the vacuum is obtained.The total radiation efficiency of the array antenna is 98.92%.Secondly,according to the quantum tunneling theory,a multi-wall carbon nanotube rectenna model was designed and built,and the basic parameters of the model were determined.3.The multi-wall carbon nanotube rectenna designed in this research is prepared,tested and optimized for system experiment.First,the carbon nanotube antenna is prepared by the chemical vapor deposition method,and the rectifier layer and the metal electrode are processed by the atomic layer deposition method and magnetron sputtering technology.Secondly,an innovative test platform for carbon nanotube rectennas was built to test the photoelectric conversion efficiency of the rectennas under laser irradiation with wavelengths of 532nm and 1064nm,and the radiation of the carbon nanotube antennas was calculated based on the equivalent circuit model and semi-classical theory.effectiveness.Finally,the radiation efficiency of the processed sample is 40.52%,and the reasons for the difference between the experimental test results and the simulation design results are analyzed.4.By comparing the test and simulation results,further optimize the carbon nanotube rectenna model,light source path and test plan.First,the local electric field of the carbon nanotube antenna model is enhanced by adding metal particles and optimizing their size.Secondly,change the light source path of the carbon nanotube rectenna,replace the substrate medium and bottom electrode with sapphire and indium tin oxide（ITO）with strong light transmission,and use the back feed method to enter the light source to enhance the photoelectric conversion efficiency.Finally,replace the two-wire connection with the four-wire system to eliminate the internal resistance of the triaxial cable and reduce the test error.