Reducing the parasitic loss of c-Si solar cells

Parasitic loss in monocrystalline silicon (mc-Si) solar cell significantly degrades the cell´s electrical performance. However, surface contamination due to the presence of organic residues and non-optimized silicon nitride properties (SiNx), and deposits by plasma- enhanced chemical vapor deposition (PECVD), lead to higher parasitic loss. In this research work, a cleaning process by using sodium hypo chlorate (NaOCl) and potassium hydroxide (KOH) is introduced before the anisotropic texturization by sodium/potassium hydroxide (NaOH/KOH) and Isopropyl alcohol (IPA) solutions. The surface morphology, reflectance factor (RF) are investigated and compared. Furthermore, SiNx layer properties have been optimized and the effect of process parameters on shunt resistance (R_SH) has been analyzed. A batch of 156 mm pseudo square (PSQ) mc-Si solar cells are fabricated with the optimized process where electrical properties are analyzed and compared with the standard one. R_SH, fill factor (FF) and efficiency are found to be higher by 40%, 1.6% (absolute) and 0.37% (absolute) respectively for the optimized process.