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和越来越高的单结和串联太阳能电池的功率转换效率而被广泛研究用于光伏电池。为了促进这一领域的进一步发展，对杂化金属卤化物钙钛矿的基本光电特性有更深入的了解是必不可少的，因为这些特性决定了器件的整体效率。到目前为止，大多数光电研究都是在孤立的钙钛矿薄膜上进行的。虽然这些研究对于理解钙钛矿层内电荷传输的基本原理很有价值，但钙钛矿太阳能电池由包括电荷传输层和电极在内的许多组件组成。该项目将评估全功能器件中的电荷-载流子重组和电荷-载流子迁移率，以便更好地了解整体电荷传输机制。它将主要使用光泵太赫兹探针（OPTP）光谱学，这是一种用于分析亚皮秒时间分辨率的光电性的通用技术。OPTP研究将在华威超快光谱中心进行，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.