Ultrafast terahertz spectroscopy of novel perovskite photovoltaics

了解钙钛矿晶体结构材料中光物质相互作用的物理学是目前一个非常活跃和令人兴奋的话题。无机-有机杂化钙钛矿提供了一种全新的光电材料，具有优异的光伏性能（超过22%的太阳能转换效率），并且在光发射器中具有进一步的应用潜力。然而，人们对光被这些化合物吸收后发生的物理现象知之甚少：一些研究得出结论，自由的、可移动的电荷是直接产生的，而另一些研究报告了激子结合电子-空穴对的形成。在这个博士项目中，学生将使用超快太赫兹光谱研究自由电荷和激子是如何产生并随后移动的。这是一种先进的实验方法，可以探测材料对持续时间<1ps的光脉冲的反应时的电导率。

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.