Electrical Characterization of CIGS Thin Film Solar Cells by Two and Four-Wires Probe Technique

The characterization of thin film solar cells is of huge importance for obtaining high open circuit voltage and low recombination rates from the interfaces or within the bulk of the main materials. Among the many electrical characterization techniques, the two and four wire probe using the Cascade instrument is of interest since the resistance of the wires, and the electrical contacts can be excluded by the additional two wires in 4 wire probe configuration. In this paper, both two and four-point probes configuration are employed to characterize the CIGS chalcogenide thin film solar cells. The two wire probe has been used to measure the current-voltage characteristics of the cell which results in a huge internal resistance. Therefore, the four wire connection are also used to eliminate the lead resistance to enhance the characterization accuracy. The load resistance in the twowire probe diminishes the photogenerated current density at smaller voltage ranges. In contrast, the proposed four wire probe collects more current at higher voltages due to enhanced carrier collection efficiency from contact electrodes. The current conduction mechanism is also identified at every voltage region represented by the value of the ideality factor of that voltage region.