Surface‐Defect Mediated Recombination Dynamics of Ti 3 C 2 T x MXene Flakes

ABSTRACT Controllable electrical and optical properties of MXenes (Ti 3 C 2 T x ) have demonstrated enormous potential for electronic, photonic, and optoelectronic devices. These materials are selectively etched from MAX phases and are highly promising for next‐generation devices due to high conductivity, tunable bandgap, and broadband absorption. Understanding the fundamental physical mechanisms of charge‐carrier dynamics and recombination pathways in Ti 3 C 2 T x is in early stages and requires further study to address low performance and charge‐transfer in optoelectronic devices. Hence, the present work investigated the key role of surface defects in affecting the recombination dynamics of layered Ti 3 C 2 T x flakes using time‐resolved photoluminescence (TRPL) spectroscopy. Wavelength‐dependent PL and Raman spectroscopies provided evidence for TiO x surface defects formation on Ti 3 C 2 T x flakes, creating defect energy levels below the conduction band. Besides, TRPL analysis revealed single‐exponential fast‐decaying behavior of 350 nm band‐edge emission via radiative recombination, while the 428 and 452 nm defect emission bands exhibit double‐exponential, slower decays via trapping from surface states. These surface defect‐assisted recombination dynamics and light‐emitting properties highlight MXenes as a new class of 2D layered materials for future optoelectronic and photonic devices.