Analysis of grain structure evolution via image processing based on optical measurements of mc Si wafers

Abstract

A fast and thorough characterization of grain structure in multicrystalline silicon (mc-Si) is crucial to improve crystal growth and thus bulk lifetime in solar cells. The presented characterization techniques are based on simple optical measurements on as-cut mc-Si wafers. An insight into the entire brick is gained by connecting 2D-information, computed via advanced pattern recognition techniques, over brick height. We identify robust statistical key parameters. Their development within typical bricks of different cast-Si techniques is compared and it is found that the distinct behavior of different materials in the lower part of the brick subsides towards the brick top where grain size distribution is similar

Printing technologies for silicon solar cell metallization: A comprehensive review

“…To ensure an adequate statistical evaluation, a certain amount of local measurements of finger segments per cell should be performed, ideally at similar position on each cell using standardized illumination conditions. The exact quantification of the relevant finger geometry parameters should be determined with adequate image analysis algorithms 243,244 to avoid subjective influences and measurement errors of manual measurements and ensure a reproducibility. Recommended three‐dimensional geometry parameters are shown in Figure 4A–D.…”

Engineering Manufacturing Education: Solar Cell Analysis and Diagnostics Using Scanning and Imaging Techniques

“…Multicrystalline solar cells are particularly interesting due to the intricate grain structures [2][3][4][5][6] which results from the details of the casting process used to solidify silicon ingots from which the silicon wafers are cut. The silicon wafers are processed into solar cells using emitter junction phosphorus diffusion step, screen printing of front and back metal contacts, and coating with an anti-reflection layer.…”