Black Silicon Solar Cell and Its Preparation Method

Abstract

A black silicon solar cell includes a metal back electrode, the crystal silicon, a black silicon layer, a passivation layer and a metal gate; wherein, the metal back electrode is located on the back surface of the crystal silicon, the black silicon layer is located on the crystal silicon, the passivation layer is located on the black silicon layer, the metal gate is located on the passivation layer. The fabrication method includes: carrying out pretreatment of the silicon wafer; preparing the black silicon layer on the surface of the pretreated silicon wafer by using plasma immersion ion implantation technology; preparing an emitter on the black silicon layer, and carrying out passivation treatment on the emitter to form the passivation layer; respectively preparing the metal back electrode and the metal gate on the back surface of the single crystal silicon wafer and the passivation layer, respectively.

What is claimed is: 
     
         1 . A black silicon solar cell, wherein, is comprised of a metal back electrode, crystalline silicon, black silicon layer, passivation layer and metal gate electrode, said metal back electrode is located on the back of the crystal silicon, the black silicon layer is located on the crystal silicon, the passivation layer is located on the black silicon layer, and the metal gate electrode is located on the passivation layer. 
     
     
         2 . The black silicon solar cell of  claim 1 , wherein, said crystal silicon is monocrystalline silicon or polysilicon, said metal back electrode is made of aluminum, cuprum, silver, gold or platinum, and said metal gate electrode is made of aluminum, cuprum, silver, gold or platinum. 
     
     
         3 . The black silicon solar cell of  claim 2 , wherein, said thickness of the metal back electrode is 10-15 microns. The thickness of the monocrystalline silicon or polysilicon is 100-300 microns. The thickness of the black silicon layer is 0.1-10 microns. The thickness of the passivation layer is 50-200 nanometers. The thickness of the metal gate electrode is 2-10 microns. The gate width of which is 30-150 micro, and the distance is 2-3 millimeters. 
     
     
         4 . A fabrication method of a black silicon solar cell, wherein, includes:
 pretreating the silicon wafer;   fabricating the black silicon layer on the surface of the pretreated silicon wafer by using plasma immersion ion implantation technology;   fabricating emitter on the black silicon layer, and carrying out passivation treatment to the emitter to form the passivation layer; and   fabricating the metal back electrode and metal gate electrode on the back of the monocrystalline silicon wafer and the passivation layer respectively.   
     
     
         5 . The fabrication method of the black silicon solar cell of  claim 4 , wherein, said step of pretreating the silicon wafer includes:
 immersing the silicon wafer into the hydrofluoric acid solution, and then washing it with deionized water;   immersing the silicon wafer which has been washed with deionized water into sodium hydroxide solution to remove damaged layer of the silicon layer; and   washing the silicon wafer whose damaged layer has been removed, and drying it with nitrogen gas.   
     
     
         6 . The fabrication method of the black silicon solar cell of  claim 4 , wherein, in said plasma immersion ion implantation technology, the step of fabricating black silicon layer on the surface of the pretreated silicon wafer includes:
 placing the silicon wafer in the implantation chamber of the plasma immersion ion implantation device;   adjusting craft parameters of said plasma immersion ion implantation device into the range of value set beforehand;   said plasma immersion ion implantation device generates plasma, and said reacting ions in the plasma are implanted into said silicon wafer; and   said reactive ions react with said silicon wafer, and the black silicon layer is formed.   
     
     
         7 . The fabrication method of the black silicon solar cell of  claim 6 , wherein, said step of placing the silicon wafer in the implantation chamber of the plasma immersion ion implantation device further includes: connecting said silicon wafer with a power supply electric which can apply bias voltage; said art parameters include base pressure and work pressure of the implantation chamber, and component and volume ratio of mixed gas implanted into the implantation chamber; the range of the base pressure is 10 −5 ˜10 −3  pa, and the range of the work pressure is 0.1 pa˜50 pa; said mixed gas is comprised of gas with etching function and gas with passivation function, and said gas with etching function includes SF 6 , CF 4 , CHF 3 , C 4 F 8 , NF 3 , SiF 4 , C 2 F 6 , HF, BF 3 , PF 3 , Cl 2 , HCl, SiH 2 Cl 2 , SiCl 4 , BCl 3  or HBr, and said gas with passivation function includes: O 2 , N 2 O or N 2 , and the range of the volume ratio of said gas with etching function and said gas with passivation function is 0.01˜100. 
     
     
         8 . The fabrication method of the black silicon solar cell of  claim 4 , wherein, said step of fabricating emitter on said black silicon layer includes:
 placing said silicon wafer into quartz container of a tubular of diffusion furnace;   bringing phosphorus oxychloride into said quartz container with nitrogen gas at a high temperature;   said phosphorus oxychloride reacts with the silicon wafer, and phosphorus atoms are formed; and   said atoms penetrating and diffusing to the inside of said silicon wafer, thus PN junction is formed.   
     
     
         9 . The fabrication method of the black silicon solar cell of  claim 4 , wherein, the step between the step of fabricating emitter on the black silicon layer and the step of passivation treatment to the emitter includes:
 placing the silicon wafer into hydrofluoric acid solution to be immersed; and   performing etching to the silicon wafer after been immersed to remove its edge.   
     
     
         10 . The fabrication method of the black silicon solar cell of  claim 4 , wherein, said passivation treatment is surface oxidation vegetating SiO 2  passivation treatment, or PECVD vegetating SiN x  or SiO 2  passivation treatment.