Local Solar Cell Efficiency Analysis Performed by Injection-dependent PL Imaging (ELBA) and Voltage-dependent Lock-in Thermography (Local I-V)

In this contribution two methods for performing local efficiency analysis of solar cells are compared with each other by applying them to a solar cell and a neighboring wafer. The first method called “ELBA” is based on injection-dependent photoluminescence (PL) imaging of a passivated wafer. The second method called “Local I-V” is based on voltage-dependent dark lock-in thermography (DLIT) on a solar cell. The results of both methods with respect to the influence of the bulk on the local solar cell parameters are comparable with each other. However, since only “Local I-V” is investigating a finished solar cell, it may image also local ohmic shunts, inhomogeneous front- and backside and depletion region recombination, and Rs effects, whereas “ELBA” is suited for assessing bulk-related efficiency losses in detail, which are not concealed by the aforementioned cell-related loss mechanisms in this method.