MXenes等离激元诱导热载流子产生与输运温度依变性

Temperature dependence of MXenes plasmons induced hot carrier generation and transport

MXenes可以实现大规模合成且具有诸多优异光电特性,被用于构建各种结构和功能独特的热载流子光电探测器件.然而,变温环境条件下MXenes并不稳定,一方面环境温度升高会加速材料氧化降解,另一方面温度变化可能影响光电器件的寿命和性能稳定性,目前MXenes温度不稳定性受到越来越多关注.鉴于实验研究变温条件下MXenes热载流子性质的局限,本文基于多体微扰理论和量子力学理论,研究环境温度对电子态分布和散射效应的影响.从表面等离激元非辐射衰减角度出发,采用第一性原理计算量化热载流子的产生效率、能量分布和输运,系统研究了MXenes表面等离激元诱导热载流子的环境温度依变特性.结果表明,MXenes中带间跃迁和声子协助电子跃迁共同高效率产生了高能热空穴主导的热载流子,且表现出与硼烯媲美的长寿命和输运距离.环境温度升高显著提高了红外波段的热载流子产生效率,同时可见光波段的热空穴表现出优异环境温度稳定性.此外,环境温度升高降低了热载流子的寿命和输运距离,主要源于增强的电子与光学声子散射效应.

Unlike conventional optoelectronic devices,plasmon-driven optoelectronic devices can efficiently realize 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 new opportunities for realizing hot carrier optoelectronic devices.As the basis for the practical application of plasmon optoelectronic devices,searching for plasmon metal materials with exceptional performance 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 can be 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 state distributions and scattering effects by using 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,in order to systematically study 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 physical mechanism of hot carrier generation in visible light is almost unaffected by the increase of ambient temperature,and the generated hot holes show excellent ambient temperature stability.In addition,the lifetime and transport distance of hot carriers decrease with ambient temperature increasing,which is mainly due to the enhanced scattering of electrons and optical phonons.The research results will provide theoretical and data support for quantitatively evaluating the ambient temperature stability of MXenes plasmon optoelectronic devices in practical environment.