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

Abstract

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 [Eu2(phen)2(bz)6] (C1), [Eu2(bphen)2(bz)6] (C2), [Eu(tta)3bphen] (C3), [Eu(bta)3pyz-phen] (C4), [Eu(tta)3pyz-phen] (C5), [Eu(bta)3me-phen] (C6), [Er(bta)3me-phen] (C7), [Yb(bta)3me-phen] (C8), [Gd(bta)3me-phen] (C9), [Yb(bta)3pyz-phen] (C10), [Er(tta)3pyz-phen] (C11), [Eu2(bz)4(tta)2(phen)2] (C12), [Gd2(bz)4(tta)2(phen)2] (C13), [EuTb(bz)4(tta)2(phen)2] (C14), [EuGd(bz)4(tta)2(phen)2] (C15), [Eu1.2Gd0.8(bz)4(tta)2(phen)2] (C16), and [Eu1.6Gd0.4(bz)4(tta)2(phen)2] (C17), can be grouped into three families based on their composition: Complexes C1–6 were synthesized using Eu3+ 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 Er3+, Yb3+, or Gd3+ ions. Complexes C12–17 have the general formula [M1M2(bz)4(tta)2(phen)2], where M1 and M2 can be Eu3+, Gd3+, or Tb3+ 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.