Characterization of 2-D reflection pattern from textured front surfaces of silicon solar cells

• 2-D reflected light distributions from various front textures are characterised.
• Patterns with rich features for inverted pyramids are explained.
• Smeared out patterns with peak intensity at 25° for random pyramids are reported.
• Differences in the reflection pattern are correlated to the surface morphology.
• Impact of the encapsulant's index on the amount of total internal R is reported.

Reflected light from textured front surfaces of a solar cell contains useful information about the surface geometry as well as the optical properties of the cell. In this study, the 2-D reflected light distributions from front surfaces of silicon cells textured in various ways are characterised by an appropriate optical setup. The results are compared to those of conventional ray tracing. For surfaces with regular inverted pyramids, we identified reflected light diffraction patterns that can be explained by the principles of geometrical optics. These reflected light patterns can be used to extract details of surface morphologies and hence be used as a tool to fine tune and monitor fabrication processes. Surfaces with random pyramids reflect light without diffraction patterns but with other distinctive features. Their reflections lie primarily in the angular range between 0° and 50°, with a maximum intensity at about 25°. The impact of the encapsulant's refractive index on the amount of total internal reflection is discussed for various types of textured surface. For both random and regularly textured surfaces, it appears possible to achieve higher total internal reflection ratio when the encapsulant's index increases from conventional 1.5 to 1.6.