Splitting one high-energy photon into two lower energy photons through downconversion has been demonstrated for a variety of combinations of rare earth (RE) ions. However, the low absorption cross section of RE3+ 4f-4f transitions hampers practical application. Therefore, enhancing the absorption by sensitization is crucial. We demonstrate efficient dye-sensitized downconversion using a strong blue/UV absorbing Coumarin dye to sensitize downconversion of the Pr3+-Yb3+ couple in NaYF4 nanocrystals (NCs). Luminescence spectra and lifetime measurements reveal Förster resonant energy transfer (FRET) from Coumarin to Pr3+ in NaYF4:Pr3+Yb3+ NCs, followed by downconversion, resulting in Yb3+ IR emission with ∼30 times enhancement. The present study demonstrates the feasibility of dye-sensitized downconversion as a promising strategy to engineer strongly absorbing downconversion NCs to enhance the efficiency of photovoltaic cells.

中文翻译：

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染料敏感的下转换。

对于稀土（RE）离子的各种组合，已经证明通过下转换将一个高能光子分成两个低能光子。但是，RE3 + 4f-4f跃迁的低吸收截面妨碍了实际应用。因此，通过敏化增强吸收至关重要。我们展示了使用强蓝/紫外吸收香豆素染料对NaYF4纳米晶体（NCs）中Pr3 + -Yb3 +夫妇的降敏进行有效的染料敏化下转换。发光光谱和寿命测量表明，在NaYF4：Pr3 + Yb3 + NC中，从香豆素到Pr3 +的Förster共振能量转移（FRET），然后进行下变频，导致Yb3 + IR发射增强约30倍。