Exotic Photothermal Response in Ti-Based MXene Optoelectronic Devices

MXenes represent one-of-a-kind materials to devise radically novel technologies and achieve breakthroughs in optoelectronics. To exploit their full potential, precise control over the influence of stoichiometry on optical and thermal properties, as well as device performance, must be achieved. Here, the characteristics of optoelectronic devices based on Ti₃C₂T_x and Ti₂CT_x thin films are uncovered, highlighting the striking difference in their photothermal responses to laser irradiation under different experimental conditions. Even though their absorption coefficients at 450 nm are comparable, the thermal excitation and relaxation phenomena display markedly different kinetics: Ti₂CT_x devices show a strong asymmetry during the heating-cooling cycle, with the heat dissipation kinetics being three orders of magnitude slower than Ti₃C₂T_x and strongly influenced by environmental conditions. The findings are expected to stimulate fundamental investigations into the photothermal response of MXenes and open exciting prospects for their use in printed and wearable optoelectronics, including memory devices and neuromorphic computing.