Development of High-Efficiency n-Type Front and Back Contact Passivated Emitter and Rear Locally Diffused Solar Cells Using Atmospheric Pressure Chemical Vapor Deposition of Phosphosilicate Glass and Laser Processing

摘要

Industrial bifacial n-type front and back contact (nFAB) silicon solar cells, consistingof a boron-doped pþ emitter and a phosphorus-doped n~+ back surfacefield (BSF), are known to give good bifaciality, high and stabilized efficiency. Onepossible approach to further enhance the cell efficiency is to convert conventionalpassivated emitter and rear totally diffused (PERT) into rear locally diffused(PERL) structure. Herein, bifacial nFAB PERT and PERL cells are fabricated bycombining atmospheric pressure chemical vapor deposition (APCVD) of phosphosilicateglass (PSG) as doping source and laser processing. For PERL cells,two approaches are studied to locally form phosphorus-doped BSF: 1) laserdoping, and 2) laser ablation of a diffusion barrier layer. For ablation approach, analkaline treatment is introduced immediately after laser process, which leads tothe formation of locally textured BSF. Due to this locally textured contact, theresultant fill factor (FF) and series resistance (Rs) loss of the PERL cells are evenless than that of the reference PERT cells. As a result, the champion cell of PERLshows a good efficiency of 21.3% with open-circuit voltage (V_(oc)) of 662 mV, shortcircuitcurrent density (J_(sc)) of 39.6 mA cm~(-2), and a high FF of 81.1%.