Enhanced Hot-Phonon Bottleneck Effect on Slowing Hot Carrier Cooling in Metal Halide Perovskite Quantum Dots with Alloyed A-Site.
basic_science · Level V
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- Record sourced from PubMed, PMID 37311157.
- Also identified by DOI 10.1002/adma.202301834.
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Abstract
A deep understanding of the effect of the A-site cation cross-exchange on the hot-carrier relaxation dynamics in perovskite quantum dots (PQDs) has profound implications on the further development of disruptive photovoltaic technologies. In this study, the hot carrier cooling kinetics of pure FAPbI<sub>3</sub> (FA<sup>+</sup> , CH(NH<sub>2</sub> )<sub>2</sub> <sup>+</sup> ), MAPbI<sub>3</sub> (MA<sup>+</sup> , CH<sub>3</sub> NH<sub>3</sub> <sup>+</sup> <sub>+</sub> ), CsPbI<sub>3</sub> (Cs<sup>+</sup> , Cesium) and alloyed FA<sub>0.5</sub> MA<sub>0.5</sub> PbI<sub>3</sub> , FA<sub>0.5</sub> Cs<sub>0.5</sub> PbI<sub>3</sub> , and MA<sub>0.5</sub> Cs<sub>0.5</sub> PbI<sub>3</sub> QDs are investigated using ultrafast transient absorption (TA) spectroscopy. The lifetimes of the initial fast cooling stage (<1 ps) of all the organic cation-containing PQDs are shorter than those of the CsPbI<sub>3</sub> QDs, as verified by the electron-phonon coupling strength extracted from the temperature-dependent photoluminescence spectra. The lifetimes of the slow cooling stage of the alloyed PQDs are longer under illumination greater than 1 sun, which is ascribed to the introduction of co-vibrational optical phonon modes in the alloyed PQDs. This facilitated efficient acoustic phonon upconversion and enhanced the hot-phonon bottleneck effect, as demonstrated by first-principles calculations.