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Light‐induced degradation in quasi‐monocrystalline silicon PERC solar cells: Indications on involvement of copper

High‐efficiency solar cell designs such as the passivated emitter and rear cell (PERC) raise the quality requirements for silicon substrates, favoring monocrystalline materials. Seed‐cast quasi‐monocrystalline silicon (qm‐Si) is a promising alternative for Czochralski (Cz) Si with potential benefits of lower cost and reduced energy footprint. However, the purity and crystalline quality of qm‐Si is not on par with Cz‐Si, which can cause efficiency losses for example in the form of light‐induced degradation (LID). In this contribution, we study the LID phenomena that can be present in qm‐Si PERC solar cells, and compare them to the Cz‐Si PERC. Degradation and regeneration are analyzed especially from the viewpoint of Cu impurity, which has until very recently been omitted as a source of LID for this device type. Subsequently, differences in LID behavior between qm‐Si and Cz‐Si are investigated considering the density of dislocations in the bulk. The results imply that slurry‐based wafer slicing may introduce contamination that is capable of causing considerable LID in PERC devices fabricated of Si with inherently high defect density.