Non-destructive photofrequency method for characterization and degradation studies of solar cells

✍ Scribed by J. Boucher; M. Lescure

• Book ID: 103902894
• Publisher: Elsevier Science
• Year: 1980
• Weight: 485 KB
• Volume: 2
• Category: Article
• ISSN: 0379-6787
• DOI: 10.1016/0379-6787(80)90100-3

✦ Synopsis

We introduce a new method of analysis for studying the degradation under stress and the reliability of solar cells.

The solar cell was illuminated with a monochromatic beam modulated by a small a.c. signal. The variations in the short~ircuit modulated photocurrent with the frequency of the signal were studied. Numerous measurements at various wavelengths were performed.

The absolute light intensity, the transmittivity of the surface and thermal effects do not affect the values of the measured parameters. Furthermore, this method, which does not use the current-voltage characteristics, appears to be more accurate than any other method based on static measurements.

We introduce a mathematical model of the measured alternating shortcircuit photocurrent.

Several electrical parameters, i.e. the lifetime, the diffusion length of excess carriers in the bulk, the effective recombination rate on the back contact and the equivalent series resistance, were determined.

The experiment consisted of the comparison of the characteristics of two devices, one of which was used as a reference; very small variations in the parameters can be achieved by this differential method.