Ultrafast Carrier and Lattice Cooling in Ti<sub>2</sub>CT<sub><i>x</i></sub> MXene Thin Films.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39575464.
- Also identified by DOI 10.1021/acs.nanolett.4c04583 and PMC identifier 11673571.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Metallic MXenes are promising two-dimensional materials for energy storage, (opto)electronics, and photonics due to their high electrical conductivity and strong light-matter interaction. Energy dissipation in MXenes is fundamental for photovoltaic and photothermal applications. Here we apply ultrafast laser spectroscopy across a broad time range (femto- to microseconds) to study the cooling dynamics of electrons and lattice in emerging Ti<sub>2</sub>CT<sub><i>x</i></sub> thin films compared to widely studied Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> thin films. The carrier cooling time in Ti<sub>2</sub>CT<sub><i>x</i></sub> is persistently ∼2.6 ps without a hot-phonon bottleneck. After hot carrier cooling is completed, the transient absorption spectra of Ti<sub>2</sub>CT<sub><i>x</i></sub> MXene can be described well by the thermochromic effect. Heat dissipation in MXene thin films occurs over hundreds of nanoseconds with thermal diffusivities ∼0.06 mm<sup>2</sup> s<sup>-1</sup> for Ti<sub>2</sub>CT<sub><i>x</i></sub> and ∼0.02 mm<sup>2</sup> s<sup>-1</sup> for Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub>, likely due to inefficient interflake heat transfer. Our results unravel the energy dissipation dynamics in Ti<sub>2</sub>CT<sub><i>x</i></sub> films, showcasing potential applications in energy conversion.