Rethinking chalcopyrite solar cells architecture for solar fuel production Léo Choubrac 1 , Hichem Ichou 1 , Julien Bonin 2,3 , Fabrice Odobel 1 , Marc Robert 2,3,4 , Nicolas Barreau 1 1 Nantes Université, CNRS, Institut des Matériaux de Nantes Jean Rouxel, IMN, F-44000 Nantes, France, 2 Université Paris Cité, CNRS, Laboratoire d'Electrochimie Moléculaire (LEM), F-75013 Paris, France, 3 Sorbonne Université, CNRS, Institut Parisien de Chimie Moléculaire (IPCM), F-75005 Paris, France, 4 Institut Universitaire de France (IUF), F-75005 Paris, France Latest developments of the chalcopyrite CIGSSe based photoelectrodes make it one of the most promising choices for photoelectrochemistry applications such as CO2 reduction as recent efforts showcased promising Faradic efficiencies at low bias potentials. [Hu et al. Journal of Catalysis, 2020 ; Robert et al. Nature Communications, 2020] However, CIGSSe technology has been developed mainly for photovoltaic application. Consequently, the prevalent device configuration encounters significant drawbacks when used in photoelectrochemical cell (PEC) systems. Firstly the opaque back contact implies the device to work under front side illumination -restricting the choice of compatible catalysts and grafting surfaces to non-absorbing materials; secondly the AZO upper layer experiences limited resilience to PEC operating conditions. Finally, standard (ie low Sulfur content) CIGSe’s band diagram is not well appropriate for the targeted electrochemical reactions: the bandgap is quite small (≈1.1 eV) and the Conduction Band Minimum (CBM) energy is too low. We thus developed chalcopyrite solar cells with a revised architecture: the wider-bandgap / higher CBM pure sulfide CIGS is grown on a transparent conductive oxide (TCO), so the device can be illuminated through this transparent back contact and a much larger varieties of upper layers and catalysts can be employed [1] . Functionalization of the front side of these electrodes with Pt for Hydrogen Evolution Reaction (HER) [unpublished yet] and with Cobalt Quaterpyridine immobilized on multi-walled carbon nanotubes for CO2 reduction reaction (CO2 RR) [2] led to devices with remarkable KPIs compared to the pre-existing litterature. The characterization and performances of these innovative catalytic photoelectrodes will be fully described and discussed, including latest unpublished results. References 1. Rethinking CIGS solar cells for rear illumination applications, L. Choubrac, F. Pineau, E. Bertin, L. Arzel and N. Barreau; Journal of Physics: Energy, Volume 7, Number 2. https://doi.org/10.1088/2515-7655/ad9acf 2. “Hybrid CIGS-Cobalt Quaterpyridine Photocathode with Backside Illumination: A New Paradigm for Solar Fuel Production”, H. Ichou, L. Choubrac, G. Suna, D. Sarkar, S. Diring, S. Jobic, J. Bonin, N. Barreau, M. Robert, F. Odobel, Angew.Chem. Int. Ed., 2025, e202423727, https://doi.org/10.1002/ange.202423727
P128
© The Author(s), 2025
Made with FlippingBook Learn more on our blog