Engineering terahertz photonic devices using semiconductor nanowires

研究的主要目标/目的：混合卤化物钙钛矿由于其高光吸收、长载流子寿命、通用的低成本加工技术等，是非常有希望用于光伏应用的半导体。在过去的十年中，它们的性能得到了显著的改善，提高了电力转换效率，并逐渐克服了温度和湿度引起的不稳定问题。半导体纳米线可以设计成实现短的载流子寿命和高的载流子迁移率，这使得它们能够在太赫兹(THz)频率下进行电子或光学开关。它们的晶体结构、小平面、形状和取向都可以控制，以实现定制的电光系数和偏振性。这些优点使纳米线有别于传统的平面半导体。本项目旨在研究和了解混合卤化物钙钛矿和半导体纳米线等半导体材料中光致载流子传输的基本光电子机制，以及调节制备因素如何改善它们的电学和光学性能。新的物理科学/工程方法：该项目将利用光泵太赫兹探测光谱高精度地研究和表征半导体纳米线和混合卤化物钙钛矿的超快电学和光学性质，这将指导太赫兹器件和钙钛矿太阳能电池的发展。

Key Objectives/Aim of the research:Mixed halide perovskites are highly promising semiconductors for photovoltaic applications due to their high optical absorption, long charge carrier lifetimes, versatile low-cost processing techniques etc. Their performance has improved dramatically over the past decade, increasing in power conversion efficiency and gradually overcoming the problems of temperature- and humidity-induced instability. Semiconductor nanowires can be engineered to achieve short charge-carrier lifetimes and high carrier mobilities, which enable them to be switched electronically or optically at high terahertz (THz) frequencies. Their crystal structure, facets, shape and orientation can be controlled to achieve tailored electrooptic coefficients and polarizability. These advantages set nanowires apart from traditional planar semiconductors.This project aims to investigate and understand the underlying optoelectronic mechanisms of photoinduced charge carriers transport within semiconductor materials such as mixed halide perovskite and semiconductor nanowires and how tuning fabrication factors improves their electrical and optical properties. Novel Physical Sciences/Engineering Methodology:The project will employ optical pump terahertz probe spectroscopy to investigate and characterise the ultrafast electrical and optical properties of semiconductor nanowires and mixed halide perovskites with high accuracy which would guide the development of terahertz devices and perovskite solar cells.