Minimising recombination losses in novel solar cell materials

具有铁电特性的半导体对于太阳能电池的应用具有潜在的兴趣，因为它们可以提供最小化重组损失的途径。V-VI-VII材料家族（如SbSI）和卤化物钙钛矿是FE材料的例子，它们也具有良性天然缺陷的好处（即能量位于带隙之外）。这两种特性都表明这些材料可以作为太阳能电池的耐缺陷材料。V-VI-VII家族也很有趣，因为它们倾向于在一维分子型结构中生长，这可能体现出有趣的新物理学以及可以在设备中利用的各向同性。然而，迄今为止，这些材料系统几乎没有在太阳能电池中进行过研究。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，分析实验测量和设计测试器件。他将使用广泛的材料和器件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（瞬态电流和电压，阻抗光谱，电流-电压）和结构分析技术，以定义材料特性。该项目利用了与卡迪夫大学物理学家（Emyr Macdonald教授和Min Gao教授）的合作，他们计划种植这种材料，并与巴斯大学的理论家（Aron Walsh教授和Jarvist Frost博士）合作，他们已经进行了初步的带结构计算。该项目还将建立在EXSS （Nelson, Ekins-Daukes, Barnes）在设备物理，材料科学和太阳能电池材料建模方面的丰富经验之上，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.