Dynamics of Energy Transfer in Perovskite Nanostructures for Optoelectronic Applications

纳米材料正在成为许多光电器件（如太阳能电池、LED和光电探测器）的重要组成部分。虽然从工程角度来看，它们的小尺寸使它们具有吸引力，但在使用纳米级半导体时存在重大挑战：由于限制效应可以限制电荷移动，光电特性会发生变化，并且表面状态可以充当电子陷阱。抵消这些影响的一种策略是通过将纳米材料结合到异质结构中来设计能量转移途径，在异质结构中可以密切控制能量的流动。该项目将研究由层状混合金属卤化物钙钛矿构建的一系列异质结构中的能量转移过程，这是一种特殊的材料，薄膜形式已经对太阳能应用具有吸引力。然而，在钙钛矿纳米材料中，额外界面的存在可以为能量损失提供额外的位置，有时以不利于器件性能的速率。在这里，异质结构的不同材料内部和之间的不同能量转移过程的速率将在多个时间尺度上进行研究，从飞秒到毫秒范围，以便更好地了解这些新材料的本征和非本征光电性能。这个实验性博士项目将使用超快光谱技术，包括光泵/太赫兹探测光谱，一种非接触式光学技术，在研究与器件应用相关的光电特性方面取得了成功。该项目将利用该大学的许多先进光谱学和显微镜能力，包括沃里克超快光谱学中心（go.warwick.ac.uk/WCUS）的资源。

Nanomaterials are emerging as important components in many optoelectronic devices such as solar cells, LEDs, and photodetectors. Although their small size makes them attractive from an engineering standpoint, there are significant challenges in working with nanoscale semiconductors: optoelectronic properties change due to confinement effects that can restrict charge movement, and surface states can act as electron traps. One strategy to counteract these effects is to design energy transfer pathways by combining nanomaterials into heterostructures, where the flow of energy can be intimately controlled. This project will investigate energy transfer processes in a range of heterostructures built from layered hybrid metal halide perovskites, an exceptional class of materials that in thin-film form is already attractive for solar energy applications. However, in perovskite nanomaterials the presence of additional interfaces can provide extra locations for energy loss, sometimes at rates that are detrimental to device performance. Here, the rates of different energy transfer processes within and between the different materials of a heterostructure will be studied on multiple timescales, from the femtosecond to the millisecond range, in order to better understand the intrinsic and extrinsic optoelectronic performance of these new materials.This experimental PhD project will use ultrafast spectroscopy techniques including optical-pump/THz probe spectroscopy, a non-contact optical technique with proven success in studying the optoelectronic properties relevant for device applications. The project will utilize many of the advanced spectroscopy and microscopy capabilities at the university, including the resources of the Warwick Centre for Ultrafast Spectroscopy (go.warwick.ac.uk/WCUS).