Permanent staff: Cuminal Yvan (MCF HDR), Martinez Frédéric (MCF), Parola Stéphanie (MCF)

PhD students: E. Giudicelli (2012-2015), A. Vauthelin (2015-2019), J. Kret (2017-2020), L. Gavotto (2020-2023).

Funding: Labex SOLSTICE (ANR-10-LABX-0022), Equipex EXTRA (ANR-11-EQPX-0016), PEPS Energie 2016 (CPV-SCELL), PEPS Energie 2017 (Heat_PV).

Academic partners: PROMES, IN2MP, INL.

 

Context and goals:

Currently, 1-sun best efficiencies of 3- to 6-junction solar cells are about 38-39 % whereas they reach 44 to 47% under concentrated light [1]. The number of junctions tends to increase over the years, always improving the solar spectrum harvesting. Fig. 1.a. presents the optimum bandgaps as a function of the number of subcells. We can observe that the fabrication of multi-junction with 4-junction and more requires materials with a wide range of bandgap values and particularly the specific value of 0.5 eV. As we can see on the cartography of the bandgap energies as a function of the lattice constant (Fig. 1.b.), it is difficult to find materials among all III-V and II-VI SC that are able to fill this requirement and especially if we would like to stay lattice-matched to standard wafers such as Ge, GaAs and InP. Our work aims at exploring a new strategy based on III-Sb alloys lattice-matched to GaSb.

 

Figure 1. a. Optimum bandgaps as a function of the number of subcells. b. Cartography of the bandgap energies as a function of the lattice constant. 

 

In fact, quaternary alloys matched to GaSb can address this concern (Fig. 2.) [2]. The 0.5 eV bandgap can be reached with the GaInAsSb alloy. Medium bandgaps from 0.726 to 1.64 eV can be achieved with GaSb and AlGaAsSb alloys and higher bandgaps with a II-VI quaternary matched to GaSb. We can also notice that the AlInAsSb alloy allows to cover a broad bandgaps range but its growth is not easy due to miscibility issues.

Figure 2. Illustration of the bandgap range covered by III-Sb alloys matched to GaSb.

 

We are able to design, fabricate and characterize III-Sb solar cells optimized (see Fig. 3.) [3]. In the first step, the cell architecture is optimized with the use of our in-house developed solvers. Based on those optimizations, the structure is grown by MBE (Molecular Beam Epitaxy) in strong collaboration with the NanoMIR team (IES). Then, we proceed with the cell fabrication in the cleanroom with dedicated equipments for antimonides. The as-fabricated solar cells are characterized and analyzed with numerical simulations.

 

Figure 3. Cycle of fabrication, characterization, modeling and optimization of III-Sb solar cells.

 

Latest results:

  • Record efficiency of GaSb single-junction solar cell (7.2 % at 1 sun) [3].
  • Elaboration of AlGaAsSb single-junction solar cells [2].
  • Elaboration of III-Sb tandem cells [4].
  • Development of a material library of III-Sb quaternary alloys for numerical simulations [2].
  • Development of a numerical 1D solver to simulate the single and multi-junction solar cells [4]. read more...
  • Development of a pseudo-3D solver to simulate the solar cells behavior under concentrated light. read more...

 

References:

[1] M.A. Green et al. « Solar cell efficiency tables (Version 53) », PIP 2019; 27:3-12.

[2] Parola S, Vauthelin A, Martinez F, Tournet J, El Husseini J, Kret J, Quesnel E, Rouillard Y, Tournié E, Cuminal Y, "Investigation of antimonide-based semiconductors for high-efficiency multi-junction solar cells", Proceedings of 7th World Conference on Photovoltaic Energy Conversion (WCPEC), 0937-0942 (2018). download link

[3] Parola S, Vauthelin A, Tournet J, El Husseini J, Martinez F,  Rouillard Y, Tournié E, Cuminal Y, "Improved efficiency of GaSb solar cells using an Al0.50Ga0.50As0.04Sb0.96 window layer", Solar Energy Materials and Solar Cells 200 (2019) 110042. download link

[4] Kret J, Tournet J, Parola S, Martinez F, Chemisana D, Morin R, de la Mata M, Fernandez-Delgado N, Khan AA, Molina SI, Rouillard Y, Tournié E, Cuminal Y, "Investigation of AlInAsSb/GaSb tandem cells - A first step towards GaSb-based multi-junction solar cells", Solar Energy Materials and Solar Cells 219 (2021) 110795. download link