Multi-layer antireflection coatings for silicon solar cells using a sol-gel technique

Abstract

In order to improve the opto-electronic conversion efficiency of solar cells, antireflection coatings (ARCs) have been drew a great attention for the application in the terrene. Generally, the coating is obtained by vacuum processing such as thermal evaporation, reactive sputtering and plasma-enhanced chemical vapor deposition (PECVD). In this work, multi-layer antireflection coatings have been performed by a modified sol-gel technique, which is low-cost and simple. The multi-layer films consisted of SiO₂ and TiO₂. The physical phase and morphology of each layer were characterized by atomic force microscopy (AFM). The TiO₂ single-layer and SiO₂/TiO₂ double-layer antireflection coatings were respectively annealed at 150°C, 350°C and 550°C. The sols of TiO₂ and SiO₂ were aged for 24 hours and then were spin coated on the Si substrate. It was found that the reflectance of double-layer ARCs was generally lower than that of single-layer ones. The reflectance of films without being aged was lower than that of sols were aged for 24 hours. In all samples, the SiO₂/TiO₂ double-layer film which was annealed at 150°C and which sols were not aged for 24 hours had the lowest reflectance.