Efficient Ice-Bath Texturing Route for Multi-Crystalline Silicon Solar Cell Application

Abstract

To minimize reflection from the flat surface, the multicrystalline silicon (mc-silicon) wafers were textured by low-temperature acid etching technique, which was optimized etching parameters (e.g. temperature and time) in HF-HNO₃-H₂O system. The textured surfaces and the light trapping property of wafers were analyzed by 3D microscope and reflection spectrum, respectively. It is found the low temperature etching process is more effective in controlling the reaction speed and obtaining favorable textured structure compared with the room temperature etching process. Moreover, the large difference exists for reaction rate affected by temperature with different etching environments. It shows the ice-bath etched wafers give rise to many deep pit textures in a short time, and was good at light trapping. The reflectance is 31% lower than that obtained from the RT etching environment. By ice-bath etching step, we achieved conversion efficiency, open circuit voltage, short circuit and fill factor as high as 17.24%, 0.617V, 8.529A and 0.81, respectively. This work establishes that it is possible to fabricate the multicrystal silicon solar cells of low cost and high efficiency using low-temperature acid etching technique.