Exploring Ln(III)-Ion-Based Luminescent Species as Down-Shifters for Photovoltaic Solar Cells.

In this work, we have compiled our research on lanthanide-based luminescent materials for use as down-shifter layers in photovoltaic (PV) mini-modules. The complexes we have prepared (C1-17), with formulas [Eu 2 (phen) 2 (bz) 6 ] (C1), [Eu 2 (bphen) 2 (bz) 6 ] (C2), [Eu(tta) 3 bphen] (C3), [Eu(bta) 3 pyz-phen] (C4), [Eu(tta) 3 pyz-phen] (C5), [Eu(bta) 3 me-phen] (C6), [Er(bta) 3 me-phen] (C7), [Yb(bta) 3 me-phen] (C8), [Gd(bta) 3 me-phen] (C9), [Yb(bta) 3 pyz-phen] (C10), [Er(tta) 3 pyz-phen] (C11), [Eu 2 (bz) 4 (tta) 2 (phen) 2 ] (C12), [Gd 2 (bz) 4 (tta) 2 (phen) 2 ] (C13), [EuTb(bz) 4 (tta) 2 (phen) 2 ] (C14), [EuGd(bz) 4 (tta) 2 (phen) 2 ] (C15), [Eu 1.2 Gd 0.8 (bz) 4 (tta) 2 (phen) 2 ] (C16), and [Eu 1.6 Gd 0.4 (bz) 4 (tta) 2 (phen) 2 ] (C17), can be grouped into three families based on their composition: Complexes C1-6 were synthesized using Eu 3+ ions and phenanthroline derivatives as the neutral ligands and fluorinated β-diketonates as the anionic ligands. Complexes C7-11 were prepared with ligands similar to those of complexes C1-6 but were synthesized with Er 3+ , Yb 3+ , or Gd 3+ ions. Complexes C12-17 have the general formula [M1M2(bz) 4 (tta) 2 (phen) 2 ], where M1 and M2 can be Eu 3+ , Gd 3+ , or Tb 3+ ions, and the ligands were benzoate (bz - ), 2-thenoyltrifluoroacetone (tta - ), and 1,10-phenanthroline (phen). Most of the complexes were characterized using X-ray techniques, and their photoluminescent properties were studied. We then assessed the impact of complexes in the C1-6 and C12-17 series on the EQE of PV mini-modules and examined the durability of one of the complexes (C6) in a climate chamber when embedded in PMMA and EVA films. This study emphasizes the methodology employed and the key findings, including enhanced mini-module efficiency. Additionally, we present promising results on the application of complex C6 in a bifacial solar cell.