Ultrafast spectroscopy of hot carrier cooling in metal halide perovskite semiconductors

金属卤化物钙钛矿正迅速成为光电器件的杰出半导体，包括作为太阳能的光伏器件。电子-声子相互作用控制金属卤化物钙钛矿中电荷的固有迁移率，并决定载流子损失能量的速率。太阳能电池中的高能载流子通常会以热量的形式失去多余的能量，而不是有效地用于发电。在这个项目中，载流子迁移率和冷却动力学将直接使用超快瞬态吸收光谱和光泵，太赫兹探测光谱的组合，在不同的组成钙钛矿检查。将开发一个模型，以提供一个定量描述的实验载体冷却动力学，无论是有和没有大量的热声子人口。从实验和理论的结合理解将允许不同的金属阳离子（如铅或锡）和不同的卤素阴离子（如I或Br）的合金的冷却动力学的变化被建立。其目的是提供基本的洞察因素，改变载体冷却，以建立潜在的使用热载体在未来的设备架构。

Metal halide perovskites are rapidly emerging as outstanding semiconductors for optoelectronic devices, including as a photovoltaic for solar power. The electron-phonon interaction controls the intrinsic mobility of charges in metal halide perovskites, and determines the rate at which carriers lose energy. Energetic carriers in a solar cell typically lose their excess energy as heat, rather than usefully contributing to power generation. In this project the carrier mobility and cooling dynamics will be directly examined using a combination of ultrafast transient absorption spectroscopy and optical pump, THz probe spectroscopy, in perovskites with different compositions. A model will be developed to provide a quantitative description of the experimental carrier cooling dynamics, both with and with out a substantial population of hot phonons. The combined understanding from experiment and theory will allow changes in cooling dynamics for alloys with different metal cations (e.g. Pb or Sn) and different halide anions (e.g. I or Br) to be established. The aim is to provide fundamental insights into factors that alter carrier cooling in order to establish the potential to use hot carriers in future device architectures.