Laboratoire Charles Coulomb UMR 5221 CNRS/UM2 (L2C)


Accueil > La Recherche > Axes & Equipes > Physique Appliquée > Semi-conducteurs : Graphène, grand gap & Photovoltaïques > Photovoltaïque et mono-chalcogénures

Electrical studies

par Olivier BRIOT - publié le

The base measurement to be performed on solar cell devices is to measure their behaviour in terms of energy conversion efficiency.
This is done by realizing an i(V) measure under illumination. The illumination must be standardized, according to the AM1.5 specification. A solar simulator, equipped with appropriate filter and calibrated with a reference cell reproduces the AM1.5 solar illumination, and the I(V) characteristic is plotted using a KEITHLEY 2400 sourcemeter, which acts as a programmable load.

The I(V) characteristics allow for the extraction of conversion efficiency, open circuit voltage (Voc), short circuit current (Icc), and fill factor (FF), this latter parameter qualifying the quality of the junction and the whole process and contacts.
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In order to get in-depth analysis of the previous measurement, it is possible to use monochromatic light to perform a measure of the conversion efficiency versus wavelength. This is the so-called External Quantum Efficiency (EQE) Measurement. Information can be obtained on separate zones of the solar cell, on the recombination paths, ...
We have realized a homemade system based on a white lamp, a JY-25 Jobin Yvon monochromator and a Fluke 8808 numerical multimeter. Two calibration photodiodes (Si and InGaAs) allow the precise determination of the incoming light flux.

For single material layers, it is possible to perform resistivity and Hall effect measurements, in order to determine their residual doping and mobility.
We use an ECOPIA HMS3000 automated system which perform fast and accurate measurements.

More convoluted analysis are possible by measuring the capacitance of the junction versus polarization, temperature, frequency. We perform such measurements using an HP4284A capacimeter.