Design And Fabricate All-Back-Contact Thin-Film Silicon Solar Crll

The all-back-contact thin-film crystalline silicon solar cell has a coplanar PN junction and a fully exposed light receiving surface.All-back-contact electrode can avoids the optical loss completely that caused by the shadow of the upper electrode,which is particularly important for thin film solar cell.In addition,the coplanar PN junction can reduces the surface recombination and improves the utilization rate of incident light with short wavelength by changing the transport path of the carrier and separating the short wavelength absorption region from the surface “dead layer”.This thesis studied all-back-contact thin-film solar cells including the contents as follows:Firstly,the optical losses and electrical losses that affect the performance of conventional solar cells were analyzed.We elaborated the influence of using this all-back electrode structure in the thin-film solar cell.Elaborated the influence of using this electrode structure to the thin-film solar cell.Then,we analyzed the optical and electrical characteristics of all-back contact solar cell which is superior to the front-rear electrode solar cell by using semiconductor simulation tool TC AD.The factor that affect the performance of solar cell,such as the contact width between electrode and P+/N+ region,doping concentration and the width of electrode contact,were studied respectively and the optimized solar cell parameters were obtained.Furthermore,on the basis of the optimized structure parameters,we carried on the research of the fabrication technology for all-back contact thin-film crystalline silicon solar cell.The principle of thermal oxidation,diffusion,photolithography,electron beam evaporation and silicon wafer thinning were introduced respectively.All the processing conditions were determined and consequently the all-back contact thin-film crystalline silicon solar cell were prepared.Finally,the J-V curve of all-back contact thin-film solar cell with silicon nitride antireflection coating and random pyramid light-trapping structures were tested and analyzed respectively.The silicon nitride thin-film was deposited by PECVD and pyramid light-trapping structure was prepared by using the anisotropic etching characteristics of silicon,the J-V curve were measured.Compare to the flat solar cell,the conversation efficiency of solar cell with silicon nitride ARC and pyramid textures have 31% and 41.4% improvement respectively.