A novel additive for rapid and uniform texturing on high-efficiency monocrystalline silicon solar cells

Abstract

The wet etching process that produces the textured surface consisting of pyramid structures has been a mature technology for mono-crystalline silicon (mono-Si) solar cells due to the advantages of its low fabrication cost as well as the excellent light trapping effect of such textured surface. Chemical additives such as hazardous solvents like isopropanol are commonly used to effectively assist the fabrication of pyramid structures in addition to the main alkali solution. In this paper, a novel additive that does not contain the hazardous solvents like isopropanol has been developed. The wet etching process using this additive can produce uniform pyramid structures on Si surface in just 7 min, which is at least 3 min shorter than the conventional wet etching process. The composition of this additive is systematically studied and analyzed in terms of the cell performance. We also compare the surface morphology, reflectivity, minority carrier lifetime, quantum efficiency and electroluminescence (EL) of the Si wafers with different textured surface produced by wet etching process using different additives. The results show that such novel additive contributes to the rapid formation of homogeneous small pyramid structures on the Si surface. The open circuit voltage, short circuit current density, fill factor and conversion efficiency of the corresponding passivated emitter and rear cell (PERC) solar cells using such wet etching process are greatly improved, reaching 680 mV, 40.1 mA/cm2, 81.3% and 22.18%, respectively.