Temperature-dependent study of plasmon-induced hot carrier generation and transport in Mxenes

Abstract

Different from conventional optoelectronic devices, plasmon-driven optoelectronic devices achieve efficient energy conversion and regulate the energy distribution of hot carriers through high-energy, non-equilibrium "hot" electron-hole pairs (hot carriers) generated by surface plasmon non-radiative decay, thereby presenting novel opportunities for the advancement of hot carrier optoelectronic devices. As the basis for the practical application of plasmon optoelectronic devices, the quest for exceptional performance plasmon metal materials has always been an important topic in the field of hot carrier optoelectronic devices. Currently, MXenes can be synthesized on a large scale and has excellent photoelectric properties, so it is used to build a variety of hot carrier photodetectors with unique structures and functions. Unlike the fixed surface ends of two-dimensional materials such as graphene, MoS2 and borophene, MXenes has an abundance of surface functional groups. However, the increase of ambient temperature will accelerate the oxidation modification of surface functional groups, thus affecting the life and performance stability of optoelectronic devices. In view of the inherent limitations of experimental research on dynamic characteristics of hot carriers at continuous temperatures, we study the temperature effects on the electronic states distributions and scattering effects based on the theory of multi-body perturbation and quantum mechanics. Particularly, we introduce temperature effect into interband electron transition and phonon-assisted electron transition process to obtain temperature dependent dielectric function. From the perspective of non-radiative decay of surface plasmon, we quantify the hot carrier generation efficiency, energy distribution and transport characteristics by first principles calculations, so as to achieve a systematic study of the ambient temperature dependence of plasmon-induced hot carriers in MXenes. The results show that the interband transition and the phonon-assisted electron transition in MXenes together efficiently produce high-energy hot hole-dominated carriers with a long lifetime and transport distance, which is comparable to borophene. The increase of ambient temperature significantly improves the hot carrier generation efficiency in the infrared range. Meanwhile, the increase of ambient temperature almost does not affect the physical mechanism of hot carrier generation in the visible light, and the generated hot holes show excellent ambient temperature stability. In addition, the increase of ambient temperature decreases the lifetime and transport distance of hot carriers, mainly due to the enhanced scattering of electrons and optical phonons. The research results will provide theoretical and data support for quantitative evaluation of ambient temperature stability of MXenes plasmon optoelectronic devices in practical environment.