Photothermal effects control ultrafast charge transport in titanium carbide MXenes

TL;DR

This paper explores how light-induced heat affects the electrical properties of titanium carbide MXenes, revealing a long-lasting reduction in conductivity.

Contribution

The study provides a unified understanding of photothermal effects in Ti₃C₂ MXenes and their impact on charge transport.

Findings

Photoexcitation causes long-lived suppression of conductivity in Ti₃C₂Tₓ MXenes.

The observed effect is attributed to lattice heating and slow heat dissipation.

Residual heat in Ti₃C₂Tₓ lasts over 100 ns, much longer than in conventional metals.

Abstract

Titanium carbide MXene (Ti₃C₂Tₓ) is an emerging metallic material with promise for (opto)electronics and thermal management. Yet how photoexcitation—particularly via photogenerated thermal energy—modifies its charge carrier dynamics remains poorly understood. By combining time-resolved terahertz spectroscopy and transient reflectance measurements, we reveal a long-lived, photo-induced suppression of conductivity, which we attribute to efficient lattice heating and slow heat dissipation in Ti₃C₂Tx. A systematic variation of pump photon energy reveals that this ‘negative’ photoconductivity can equivalently be induced by lattice temperature increases, indicating a thermal origin. Repetition-rate-dependent transient reflectance measurements further show residual heat persisting over 100 ns, substantially longer than in conventional metals. Our work presents a unified understanding of photothermal effects in Ti₃C₂Tₓ and their influence on non-equilibrium charge transport, underscoring its potential for photothermal electronics and light-to-thermal energy storage applications.

The authors report long-lived pump-induced conductivity suppression in metallic Ti3C2 MXenes using ultrafast terahertz and reflectance spectroscopy. The effect is attributed to strong photothermal heating and slow heat dissipation.

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