Negative Thermal Quenching in Quantum-Cutting Yb<sup>3+</sup>-Doped CsPb(Cl<sub>1-</sub><i><sub>x</sub></i>Br<i><sub>x</sub></i>)<sub>3</sub> Perovskite Nanocrystals.
basic_science · Level V
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- Record sourced from PubMed, PMID 37606982.
- Also identified by DOI 10.1021/acsnano.3c05053.
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Abstract
Ytterbium-doped all-inorganic lead-halide perovskites (Yb<sup>3+</sup>:CsPb(Cl<sub>1-<i>x</i></sub>Br<sub><i>x</i></sub>)<sub>3</sub>) show broadband absorption and exceptionally high near-infrared photoluminescence quantum yields, providing opportunities for solar spectral shaping to improve photovoltaic power conversion efficiencies. Here, we report that Yb<sup>3+</sup>:CsPb(Cl<sub>1-<i>x</i></sub>Br<sub><i>x</i></sub>)<sub>3</sub> NCs also show extremely strong negative thermal quenching of the Yb<sup>3+</sup> luminescence, with intensities at room temperature >100 times those at 5 K for some compositions. Analysis of this temperature dependence as a function of <i>x</i> shows that it stems from thermally activated quantum cutting related to the temperature dependence of the spectral overlap between the PL of the perovskite (donor) and the simultaneous-pair absorption of two Yb<sup>3+</sup> ions (acceptor). In the Yb<sup>3+</sup>:CsPbBr<sub>3</sub> limit, this spectral overlap goes to zero at 5 K, such that only single-Yb<sup>3+</sup> sensitization requiring massive phonon emission occurs. At room temperature, Yb<sup>3+</sup> PL in this composition is enhanced ∼135-fold by thermally activated quantum cutting, highlighting the extreme efficiency of quantum cutting relative to single-Yb<sup>3+</sup> sensitization. These results advance the fundamental mechanistic understanding of quantum cutting in doped perovskites, with potential ramifications for solar and photonics technologies.