Studying charge transport in functioning perovskite solar cells with THz pump-probe spectroscopy

为了减轻气候变化的影响，社会必须接受清洁和可再生能源作为化石燃料的替代品。由于一小时内到达地球表面的能量比一年消耗的能量还要多，太阳能是最有前途的选择之一。近年来，混合金属卤化物钙钛矿由于其易于合成以及对于单结和串联太阳能电池的功率转换效率越来越高而被广泛研究用于光伏电池中。为了促进该领域的进一步发展，更好地理解混合金属卤化物钙钛矿的基本光电性质是必不可少的，因为这些性质决定了器件的整体效率。到目前为止，大多数光电研究已经在孤立的钙钛矿薄膜上进行。虽然这些研究对于理解钙钛矿层内的电荷传输的基本原理是有价值的，但钙钛矿太阳能电池由包括电荷传输层和电极在内的更多组件组成。这个项目将评估电荷载流子复合和电荷载流子迁移率在全功能设备，以获得更好的图片的整体电荷传输机制。它将主要使用光泵太赫兹探测（OPTP）光谱，这是一种用于分析亚皮秒时间分辨率光电导性的多功能技术。OPTP研究将在沃里克超快光谱中心进行，同时进行其他稳态和时间分辨分析，包括光致发光光谱。

To mitigate the effect of climate change, society must embrace clean and renewable energy sources as alternatives to fossil fuels. As more energy reaches the Earth's surface in one hour than is consumed in one year, solar energy is one of the most promising options. In recent years, hybrid metal halide perovskites have been extensively investigated for use in photovoltaic cells due to their ease of synthesis and increasingly high power conversion efficiencies for both single-junction and tandem solar cells. To facilitate further progress in this field, a greater understanding of the basic optoelectronic properties of hybrid metal halide perovskites is essential as these properties govern the overall efficiency of devices. Until now, most optoelectronic studies have been performed on isolated perovskite thin films. While these studies have been valuable for understanding the fundamentals of charge transport within the perovskite layers, a perovskite solar cell is comprised of many more components included charge transfer layers and electrodes. This project will evaluate charge-carrier recombination and charge-carrier mobility in fully-functioning devices in order to gain a better picture of the overall charge transport mechanisms. It will primarily use Optical-Pump THz Probe (OPTP) Spectroscopy, which is a versatile technique for analyzing photoconductivity with sub-picosecond time resolution. OPTP studies will be performed in the Warwick Centre for Ultrafast Spectroscopy alongside other steady-state and time-resolved analysis including photoluminescence spectroscopy.