During the continuous research on the department a special solar cell layer structure was created. To simulate thin solar cell structures heavily doped n+ wafers with weakly doped n-type epitaxial layers were used. Due to the very low minority carrier lifetime the charge carriers generated by the light that is absorbed in the n+ layer do not add to the current of the solar cell, so the structure can be regarded as a solar cell with the thickness of the epitaxial layer only. The advantage of this method is that for the simulation of the thermoelectric behavior of thin crystalline silicon cells it is not needed to perform the complicated processing of the thin wafers.
On the samples the temperature dependence of the I-V curves and spectral response functions were measured from +5˚C to +85˚C. I-V curves can be measured by an automated measurement setup written in LabVIEW environment. It communicates with the refrigerated circulating bath with serial port. The spectral response functions were measured manually. In the software after the initialization three threads run at the same time: a continuous temperature measurement, a continuous correction of the solar cell’s offset voltage and the measurement of the solar cell (with a state machine).
Meanwhile writing the software I made a printed circuit board. The circuit includes an electric generator and a controlling unit. The controlling and the collecting of data were solved with a NI USB-6212 DAQ device.