Minimising recombination losses in novel solar cell materials

具有铁电(FE)特性的半导体在太阳能电池中的应用具有潜在的意义，因为它们可能提供一种将复合损失降至最低的途径。V-VI-VI族材料(如SbSi)和卤化物钙钛矿是FE材料的例子，它们也具有良性(即，具有位于带隙外的能量)的本征缺陷的好处。这两种性能都表明，这些材料可以作为太阳能电池的缺陷容错材料。V-VI-VII家族也很有趣，因为它倾向于在一维分子型结构中生长，这可能体现了有趣的新物理以及可以在设备中利用的各向同性。然而，到目前为止，这些材料体系在太阳能电池中的研究还很少。在这个项目中，学生将为这些铁电半导体设计一个合适的器件模型，并使用它将能带结构与光伏转换的基本过程联系起来，分析实验测量结果并设计测试器件。他将使用广泛的材料和设备表征工具来表征材料，包括光谱(光致发光、拉曼、电致发光)、电学(瞬时电流和电压、阻抗光谱、电流-电压)和结构分析技术，以确定材料特性。该项目利用了与卡迪夫大学的物理学家(Emyr Macdonald教授和Min Gao教授)以及巴斯的理论家(Aron Walsh教授和Jarvist Frost博士)的合作，他们已经进行了初步的能带结构计算。该项目还将建立在ExSS(Nelson，Ekins-Daukes，Barnes)太阳能电池材料的设备物理、材料科学和建模方面的丰富经验，包括最近在卤化铅钙钛矿方面的丰富经验。

Semiconductors with ferroelectric (FE) properties are potentially interesting for application to solar cells as they may offer a route to minimise recombination losses. The V-VI-VII materials family (such as SbSI) and halide perovskites are examples of FE materials that also have the benefit of native defects that are benign (i.e. with energies that lie out of the band gap). Both properties suggest these materials could perform well as defect tolerant materials for solar cells. The V-VI-VII family is also interesting because of the tendency to grow in one dimensional, molecular type structures, which could embody interesting new physics as well as an isotropy that could be exploited in devices. However, to date these material systems have hardly been studied in solar cells. In this project, the student will design an appropriate device model for these ferroelectric semiconductors and use it to relate band structure to the fundamental processes in photovoltaic conversion, to analyse experimental measurements and design test devices. He will characterise materials with a wide range of material and device characterisation tools, including spectroscopic (photoluminescence, Raman, electroluminescence) electrical (transient current and voltage, impedance spectroscopy, current-voltage) and structural analysis techniques, to define material properties. The project takes advantage of a collaboration with physicists at Cardiff University (Profs Emyr Macdonald and Min Gao) who plan to grow such materials and with theorists (Prof Aron Walsh and Dr Jarvist Frost) at Bath who have made preliminary bandstructure calculations. The project will also build on the strong experience of the device physics, materials science and modelling of solar cell materials in EXSS (Nelson, Ekins-Daukes, Barnes), including substantial recent experience with lead halide perovskites.