Publications de nos chercheuses et chercheurs

The exploitation of hybrid PV-thermal and PV-thermoelectric converters in the temperature range of 150 to 200 °C is currently an emerging field of research. In this context, solar cells have to be designed for operating optimally in this temperature range. Shockley-Queisser (SQ) calculations show that gallium arsenide (GaAs) is one of the optimal choices. Thus, the present work reports on the design, fabrication, and characterization of a standard GaAs solar cell, designed in the Standard Test Conditions (25 °C) but tested under thermal stress in order to analyze the physics that governs conversion performance at higher temperatures. EQE and I-V curve measurements are used to observe the decline of the cell performances at high temperature. By relating the figures of merit to the SQ limit values, it is possible to make meaningful analyses of performance at different temperatures and to compare our results with previous data sets. A key lesson is that a given cell architecture can perform better than another at room temperature but not necessarily at high temperature, thus advocating for a design of the cell in the targeted high temperature conditions. To do so, key optical and electrical properties must be investigated in the temperature range of interest. As an example, we present CTLM measurements processed with a novel parameter extraction method that includes measurement uncertainty propagation, and show that they give indications about the stack of layers to be used for the top contact grid.