Influence of surface texturing conditions on crystalline silicon solar cell performance

Abstract

We carried out the surface texturing of crystalline silicon in alkaline solutions via anisotropic etching. We achieved random pyramids of about 10 mu m in size. The size of these pyramids was then gradually reduced using a new solution. In this paper, we investigate the impact of the size of the pyramids on the emitter properties and the front electrode (Ag) contact. To make small (similar to 3.5 mu m) and large (similar to 9.0 mu m) pyramids, we controlled the texturing time and performed one-sided texturing using a silicon nitride film. We compared the formation and quality of a POCl3-diffused n(+) emitter in a furnace for small and large pyramids by using SEM images and emitter saturation current density (J(0e)) measured Quasi-Steady-State Photo-Conductance (QSSPC). For a comparison, we carried out to simulated using TCAD simulator software (SILVACO, the Athena module). After metallization, we measured the Ag contact resistance via the transfer length method (TLM). We observed the surface distributions of the Ag crystallites using SEM images. We used light I V to measure the performance of screen-printed solar cells. The efficiency of the solar cell in the case of the small and that in the case of the large pyramids improved by about 17.4% and 17.0%, respectively. We believe that differences in the emitter uniformity and the front Ag contact resistance resulted from this difference in the cell performance. Solar cells perform better when the pyramids are small. (C) 2013 Elsevier B.V. All rights reserved.