Research On Efficiency Improvement Of Photovoltaic And LED Device By Micro-nano Structure

The micro-nano structure,due to various optical properties,can be widely introduced into optoelectronic devices so as to realize its performance improvements.The research of this thesis focuses on efficient utilization of energy and takes photovoltaic and LED devices as research objects to improve efficiencies of thin-film silicon solar cells and integrated LED devices based on an overall consideration of main technical means for the current micro/nano fabrication.In addition to experimental researches of this thesis,the diffraction characteristics of various typical periodic gratings are analyzed and calculated under the rigorous coupled-wave analysis algorithm by using computer simulation calculation at first.This type of simulated diffraction phenomenon is introduced to the design of the thin-film silicon solar cell to improve the absorbing capacity of a photovoltaic device to sunlight.During simulation research of the solar cell,the design of a wavy grating is introduced into an amorphous silicon thin-film solar cell.When the period of the wavy grating is set at 0.5μm,a relatively smooth reference cell model is analyzed to have an improvement of maximum 46.44% on absorption on the basis that the absorbing characteristic of the amorphous silicon thin-film solar cell to an AM1.5 solar spectrum is obtained by simulation calculation under a two-dimensional model.Meanwhile a hexagonal close-packed dome array is introduced into a thin-film crystalline silicon solar cell under three-dimensional simulation to design a hexagonal close-packed dome array based thin-film crystalline silicon solar cell.The absorbing capacity of the hexagonal close-packed dome array based thin-film crystalline silicon solar cell is obtained by simulation calculation,and the maximum absorption improvement relative to that of the reference cell model is analyzed to be 45.13% when the optimal period value of the array is 0.70μm.The experimental research part of this thesis mainly focuses on implementing fabrication of micro array structures and introducing the fabricated micro arrays to related devices.The research of this part introduces in details the process for fabricating micro hemisphere hole arrays on a glass substrate,a PSS process and the process for casting micro array structures from the sapphires fabricated by the PSS process,and also introduces characterization,optical measurement and material surface performance measurement of the fabricated micro arrays.By introducing the micro hemisphere hole arrays fabricated on the glass substrate into the incident surface of the amorphous silicon thin-film solar cell,the performance improvement of the solar cell is realized,the short-circuit current is increased by 7.66%,and the maximum conversion efficiency is improved by 5.33%.The increase of 7.97% of short-circuit current and the improvement of 8.8% of the maximum conversion efficiency are realized by introducing a micro tapper hole array cast on PDMS into the amorphous silicon thin-film solar cell.In the research of a packaging technology of the integrated LED devices,the luminous efficiency of the devices is improved by introducing micro-arrays into packaging polymers of the devices.Under the same type of test condition,for the integrated LED devices packaged with micro-array structures on surfaces,compared with conventionally packaged devices,the luminous efficacy under different injection currents is improved by 23.41%-24.43% and the radiation efficiency is improved by 22.24%-23.94%.The research contents of the full thesis are closely related to the optical characteristics of the micro-nano structure,and the technologies used in experiments give priority to low-cost processes and take compatibility of the devices into consideration.The thesis comprise main innovation points as follows: two types of thin-film silicon solar cell models with micro-nano structures are designed by using computer simulation,and the absorbing capacity of the thin-film solar cells based on the micro-nano structures with low aspect ratio is analyzed;the micro-array structures are introduced into the incident surfaces of the solar cells according to structural characteristics of the amorphous silicon thin-film solar cells to ensure that the photovoltaic devices can absorb the sunlight more effectively and the conversion efficiency of the devices is improved;and the micro-array structures are introduced into the packaging polymers according to packaging characteristics of the integrated LED devices to improve the luminous efficiency.Along with the continuous improvement of the micro-nano processing technology and continuous promotion of the photovoltaic and LED devices,the application of newer and more mature technologies for improving the conversion efficiency of photoelectric devices will attract more attention.