Investigation Of The Optical Properties For Nanorod-Grating Assembly Structure And The Near-Field Radiative Heat Transfer For Disks

Global warming,environmental pollution,fossil energy depletion and other issues are increasingly becoming serious threat to human survival.The utilization of solar energy can effectively solve problems of environment and energy.Solar cells are widely used in the world.In order to improve the absorptance of solar cells,two kinds of assembly structures are proposed,which can be applied to absorption layer of solar cells.In addition,the effective management of the heat flux can also relieve problems of environment and energy.And the heat flux rectification is an important way of heat management.A heat flux rectification scheme is proposed,which can be applied to the micro/nanometer thermal rectifier.An assembly structure I is presented,which is composed of silicon nanorods and one-dimensional silicon gratings on a semi-infinite silicon substrate.The finite-difference time-domain method is used to calculate the absorptance of the assembly structure I in the 300-1100 nm wavelength region.The average absorptance of assembly structure I is greater than those of grating structure and nanorod structure.The average absorptance of assembly structure I can reach 0.955,and the conversion efficiency can reach 25.75%.This high absorptance is attributed to guided mode resonance and microcavity effect.In order to further improve the absorptance,the assembly structure II is proposed,which incorporates germanium nanorods and two-dimensional silicon gratings.The absorptance and the conversion efficiency of assembly structure II are 0.983 and 26.45%,respectively.The high absorptance of assembly structure II is mainly attributed to the guided mode resonance and Fabry–Perot resonance identified by analyzing the electromagnetic field.A micro/nanometer scale heat flux rectification scheme is proposed,which is composed of two disks.The radiative heat transfer varies with the rotation of the low temperature disk.The radiative heat transfer of thermal rectifier in silicon and n-doped silicon is calculated by the fluctuating-surface-current formulation.The radiative heat transfer is directly affected by the flux spectrum.The thermal rectification performance is effected by the heat absorption area of low temperature and the near-field effect of two disks.The influence of the non-parallelism of two disks on the radiative heat transfer is illustrated by the investigation of the thermal rectifying coefficient at different angles.