Ultrafast terahertz spectroscopy of novel perovskite photovoltaics

理解具有钙钛矿晶体结构的材料中的光-物质相互作用的物理是目前非常活跃和令人兴奋的课题。无机-有机杂化钙钛矿提供了一类全新的光电材料，具有优异的光伏性能（超过22%的太阳能转换效率），并且具有在发光体中使用的进一步潜力。然而，人们对这些化合物吸收光后发生的物理现象知之甚少：一些研究得出的结论是，直接产生了自由的、移动的电荷，而另一些工作则报道了激子结合的电子空穴对的形成。在这个博士项目中，学生将研究自由电荷和激子是如何产生的，并随后移动，使用超快太赫兹光谱。这是一种先进的实验方法，可以探测材料的电导率，因为它们响应于持续时间小于1 ps的光脉冲。

Understanding the physics of the light-matter interaction in materials with the perovskite crystal structure is an extremely active and exciting topic at present. Inorganic-organic hybrid perovskites have provided an entirely new class of optoelectronic materials with excellent photovoltaic performance (over 22% solar power conversion efficiency), and have further potential for use in light emitters. However, the physics of what happens after light is absorbed in these compounds is poorly understood: some studies have concluded that free, mobile charges are created directly, while other work has reported the formation of excitons - bound electron-hole pairs. In this PhD project the student will investigate how free charges and excitons are created and subsequently move, using ultrafast terahertz spectroscopy. This is an advanced experimental method that probes the conductivity of materials as they respond to pulses of light with <1ps duration.