Several phenomena limit the efficiency of solar cells (c-Si, CIGS…), such as the thermalization of photons with energy higher than the bandgap or the low spectral response in the ultraviolet (window layers…). A possible solution is to better match the bandgaps to the solar spectrum by fabricating tandem solar cells. Another solution is to adapt the solar spectrum to the existing solar cell by converting ultraviolet photons towards the visible or near-infrared before being absorbed by the cell. Downshifting and downconversion consist in converting an ultraviolet photon into respectively 1 or 2 photons in the visible or near-infrared. We study several downshifting and downconversion systems, in the form of oxide thin films or polymers functionalized with coordination complexes. Our functionalized encapsulants with photon conversion by photoluminescence allow an increase of conversion efficiency from 13.5 to 14.3 % in CIGS solar cells.

[1] Photon conversion in Tb,Yb:CaxSr1-xAl2O4 nanocrystals, T. Fix, H. Rinnert, J.-L. Rehspringer, A. Slaoui, Journal of Luminescence 202, 377 (2018)

[2] EuIII-based nanolayers as efficient downshifters for CIGS solar cells, A. Gavriluta, T. Fix, A. Nonat, A. Slaoui, J.-F. Guillemoles, and L. J. Charbonnière, Eur. J. Inorg. Chem., 5318-5326 (2017)

[3] Tuning the chemical properties of europium complexes as downshifting agents for copper indium gallium selenide solar cells, A. Gavriluta, T. Fix, A. Nonat , A. Slaoui, J-F. Guillemoles , L. Charbonnière, Journal of Materials Chemistry A 5, 14031 (2017)

[4] Enhancement of silicon solar cells by downshifting with Eu and Tb coordination complexes, T. Fix, A. Nonat, D. Imbert, S. Di Pietro, M. Mazzanti, A. Slaoui and L. J. Charbonnière, Progress in Photovoltaics: Research and Applications 24, 1251 (2016)

[5] Enhancement of CIGS solar cells using europium complex as photon downshifter, A. Gavriluta, T. Fix, A. Nonat, M. Paire, A. Slaoui, L. J. Charbonnière, J.-F. Guillemoles, Adv. Opt. Mater. 4, 1846 (2016)