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), [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 & beta;-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.