Abstract
A simple technique is described for selective observation of those grain boundaries in polycrystalline Si that would be most harmful to the properties of a solar cell if a cell were to be made from that material. The technique is based on the alteration of the optic axis of liquid crystals by fringing fields at the surface of polycrystalline Si. It is found that the pattern of boundaries seen this way correlates well with the pattern of the most active boundaries as seen in a light‐spot scan of a solar cell. This technique has revealed that in p‐type Wacker ’’Silso’’ material, the electrical properties of grain boundaries are strongly affected by heat treatment.