Dispositifs photovoltaïques inorganiques encouches minces pour une alimentation soutenable de l'internet des objets

Janvier 2024 – Juin 2027

Coordinateur IMN du projet :  Thomas Lepetit (équipe MIOPS)

Personnels IMN impliqués : Nicolas Barreau (équipe MIOPS)

 

The objective of the project is to produce energy for IoT devices from ambient artificial light using thin film solar cells based on stable, inorganic CuGaSe2 (CGS) chalcopyrite semiconductor grown on flexible substrates. Such devices have the potential to convert up to 50% of the indoor artificial light spectrum since the 1.7eV bandgap of the absorber allows the absorption of all of the above 1.8 eV-photons of the LED spectra without excessive thermalization losses. The synthesis of large-scale, homogeneous, single-phase, wide bandgap CGS thin films is challenging, especially at low temperature, which is necessary for deposition on flexible substrates. Such semiconductor growth being limited by slow kinetics of formation, high efficiency devices are generally obtained using long relaxion steps at high substrate temperature. We recently demonstrated that metal halide post-deposition treatments can be used to drastically decrease the synthesis temperature of CIGS films as well as produce single phase CGS thin film with large grains. This new and unique approach consisting in using metal halides as transport agent enhancing grains growth has therefore all the ingredients to break the technological locks that, to date, restrain the use of stable and industrially compatible CGS compounds for Indoor PV applications on flexible substrates. This project will also focus on heavy alkali post-deposition treatments in a sulphur atmosphere in order to improve the bulk and junction quality based on such absorber, since IMN has developed and masters this type of treatments on narrow bandgap. Finally, the material consumption will be optimized by reducing the thickness of the layers constituting the cell stack and the toxic CdS buffer layer will be replaced by an alternative buffer layer based on non-toxic and earth-abundant materials.