A continuous, single-face wet texturing process for industrial multicrystalline silicon solar cells using a surfactant treated photoresist mask

In this paper, a high-throughput continuous, single-face texturing method was introduced into the fabrication process for industrial multicrystalline silicon solar cell production. With a patterned photoresist film as the mask for the wet etching, wafers without back protection were transported by rollers and only the masked face could contact the etching solution and be etched through the mask openings. The first etching results indicated that serious heat aggregation and poor wettability of the acid solution on the mask surface resulted in a seriously uneven and uncontrolled etching reaction. However, after applying a surfactant to the photoresist mask to improve the mask's hydrophility, a stable and uniform etching reaction could be achieved. A honeycomb-like textured surface with a pitch of 18 µm was fabricated successfully. The etched pits had a nearly smooth spherical segment surface and a surface occupancy of 70%. This regular textured surface had a low in-plane average reflectivity of approximately 20% and greatly increased the carrier lifetime. Compared with multicrystalline silicon solar cells textured by conventional acid etching, the average efficiency increased from 18.31% to 18.57%. In addition, this texturing technique is expected to promote the application of diamond-wire cut multicrystalline silicon wafers in the future.