Research And Application Of Reaction-diffusion Etching Process

In the case of thin-film solar cells,efficient fabrication of light trapping array structure with less cost on the glass substrate is hot research issues in the photovoltaic industry.The traditional lithography,laser direct writing and reaction ion etching process can accurately fabricate the light trapping array structure,but it requires expensive device,and complex processes also increase the costs and production cycles.Although Micro-contact printing can form self-assembled monolayer on metal surface through silicon-oxygen bond,this self-assembly process is mostly Confined to a chemical reaction between mercaptan and gold.More importantly,the flexible stamp provides few chemical reagents at the reaction interface,and it can not get effective supplement in the reaction process.This limitation makes the micro-contact printing method can not get a relatively deep etching to the substrate.At present,it is mainly used for lithography of the micro-nano structure.A fabrication method for light trapping array structure via reaction-diffusion etching is presented.Cr/Cu seed layer on the glass substrate is microstructured and then the tub-shape micro-pit array structure glass is obtained by wet etching with Cr/Cu as the mask.Firstly,a mixture solution of Ce?NH₄?₂?NO₃?₆ and C₂H₅OH is studied and prepared.Secondly,A stamp with array structure have sufficient absorption of the reaction etching agent,and this PDMS is used as the reaction-diffusion etching mould.The agent from the internal diffusion of the flexible stamp can microstructure the substrate on the contact interface.Then the Cr/Cu seed layer on the quartz glass substrate is used as the mask of wet etching.Finally,a two-dimensional periodic tub-shape micro-pit array structure on this quartz glass substrate can be obtained by use of HF solution etching it.Incident photon-to-electron conversion efficiency of the micromorph tandem solar cells is enhanced when this tub array structure with the above process is served as a antireflection.Study shows that the efficiency of the micromorph tandem solar cells with the tub array structure glass can be enhanced up to 10.08%,which is relatively 3.07%larger than that with smooth glass.The tub array glass can also reduce the average surface reflectance from 9.13%to 8.87%with wavelengths of 300¹100 nm.The average transmission haze of the tub light trapping array structure on the glass is up to 49.45%.The average surface reflectance of this tub-shape micro-pit array structure by covering crystalline silicon is 22.28%while the smooth glass is 27.15%.Incident photon-to-electron conversion efficiency of the micromorph tandem solar cells is enhanced when this tub-shape micro-pit array structure is served as a antireflection.This fabrication method for light trapping array structure on the glass via reaction-diffusion etching can be widely used as a antireflection of the micromorph tandem solar cells to enhance the solar cells efficiency.