An optimized textured structure is a key for high efficiency multi-crystalline silicon solar cell. In this work, black silicon wafers with various structures have been successfully produced by plasma immersion ion implantation. The surface morphology, reflectance and internal quantum efficiency have been investigated by atomic force microscope, spectrophotometer and quantum efficiency measurement system, respectively. Results show that nanohillocks with average height of 150-600 nm have been generated on black silicon surfaces by different texturing conditions, and the reflectance over the wavelength from 300 nm to 1100 nm decreases with increasing the height of nanohillocks, whereas the internal quantum efficiency worsens. The solar cell based on the optimized nanohillocks height of 300 nm yeilds efficiency of 15.99% with short circuit current of 34.0 mA/cm(2). (C) 2012 Elsevier B.V. All rights reserved.