Study Of Low Reflectance Light Trap And Processing Technic In The Photovoltaic Crystal Silicon Surface

Solar energy is a kind of infinite and green energy for human beings,silicon serve as a dominant and significant material of solar cells,decreasing the reflectance in surface and increasing optical path of light in active layer of silicon cells to improve photoelectric conversion efficiency have been the focus of research in the world.As a kind of widely used texture preparation method,traditional alkali corrosion could form pyramidal microstructure in the surface of silicon,but the reflectance is difficult to decrease further as the top angle of the pyramidal structure is an inherent 70°.Currently,a rapidly developing method MAEE(Metal-Assisted Electro-less Etching)could arbitrarily distributed SiNWs(Si Nanowires)surfaces with dimension ranging from tens of microns to hundreds microns in polycrystalline silicon,which appear to completely absorb lights of all wavelengths in wide range of incidence.However,A high ratio of surface to volume of SiNW arrays could initiate higher surface recombination velocity,which decay the PCE(Power Conversion Efficiency)of silicon solar cells.At present,the need to prepare miniature components with complicated structures and high accuracy with features or dimensions ranging from several microns to several millimeters has driven the researches on micro manufacture process,especially for silicon,which play a significant role in necessary area of applications such as MEMS and optoelectronics.Mechanical texturization of silicon surface emerges this background,as a clean a method the waste of silicon is easy to recycle,the mechanical texturization research in the surface of silicon is very meaningful.The major work in this paper is following:Matlab was used to program the mathematical algorithm which involves a utilization of Fresnel equations,to simulate the propagation path of light in arc-shaped,rectangular,semicircle-based rectangular micro trap formed by mills in the surface of silicon solar cells,and the reflectance of each structures were calculated and analyzed.Besides,the reflection ruler of rectangular groove was obtained by rigorously geometrical derivation,the result of an optimized structure could guide the subsequent mechanical texturization.By reviewing the ductile mode cutting theory of single crystal silicon,formulas enable to achieve ductile mode cutting of single crystal silicon was derived,and the corresponding width of the uncut chip and feed speed were analyzed and calculated, in addition,FEA model of single crystal silicon was developed,and the influence of overhang value of tools on natural frequencies was considered to keep subsequent experiment proceeding in a safe condition.Guided by ductile mode machining theory of single crystal silicon,two types of diamond coated cemented carbide micro mills in different diameters were used to carry out the study of rectangular microstructure machining along different crystal orientations,to achieve corresponding low reflectance structure,feasibility and steps of rectangular groove machining were researched,the worn tools were observed and reflectance of rectangular groove formed in experiment was analyzed at last.