Ultrafast electrical solar cell parameter visualisation
SunsPZ© is a Matlab based software developed at SERIS that creates and displays spatially resolved electrical parameter images for silicon wafers and silicon solar cells using photoluminescence (PL). As the method is contactless, it can be applied throughout the solar cell fabrication process, even before junction formation. The parameters obtained by the new method were compared to the results obtained by the well-established Suns-Voc measurements and were found to be in good agreement [1].
The required inputs are:
- A PL image of the sample at one-Sun illumination without current extraction
- A PL image of the sample at maximum power point
- The sample’s Voc (open circuit voltage) or iVoc (implied Voc) value
With these three inputs, the software is able to provide spatially resolved images of the (implied-)Voc and pseudo fill factor (pFF) which are computed in less than a second for one-megapixel images on a standard personal computer. Statistics such as the mean and standard deviation for both parameters are supplied as well.
The Graphical User Interface (GUI) for the software
The results can be stored as images or text files. This information can then be used for process control, process development and troubleshooting. SunsPZ© is already used by a Tier-1 solar cell company to optimise their production processes.
SERIS is currently working on the next version of the SunsPZ© software whereby the visualisation of the local ideality factor m and of the emitter saturation current density J0e will be added. It is expected that this version of the SunsPZ© software will be released in 2014. Future versions of SunsPZ© will also allow visualisation of the diode saturation current density.