Polycrystalline materials are ubiquitous in technology, and grain boundaries have long been known to affect materials properties and performance. First principles materials modeling and electron microscopy methods are powerful and highly complementary for investigating the atomic scale structure and properties of grain boundaries. In this review, we provide an introduction to key concepts and approaches for investigating grain boundaries using these methods. We also provide a number of case studies providing examples of their application to understand the impact of grain boundaries for a range of energy materials. Most of the materials presented are of interest for photovoltaic and photoelectrochemical applications and so we include a more in depth discussion of how modeling and electron microscopy can be employed to understand the impact of grain boundaries on the behavior of photoexcited electrons and holes (including carrier transport and recombination). However, we also include discussion of materials relevant to rechargeable batteries as another important class of materials for energy applications. We conclude the review with a discussion of outstanding challenges in the field and the exciting prospects for progress in the coming years.

中文翻译：

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用于能源应用的多晶材料的晶界：第一原理建模和电子显微镜

多晶材料在技术中无处不在，人们早就知道晶界会影响材料的特性和性能。第一原理材料建模和电子显微镜方法对于研究晶界的原子尺度结构和特性来说是强大且高度互补的。在这篇综述中，我们介绍了使用这些方法研究晶界的关键概念和方法。我们还提供了许多案例研究，提供了它们的应用示例，以了解晶界对一系列能源材料的影响。所提出的大多数材料都对光伏和光电化学应用感兴趣，因此我们更深入地讨论了如何利用建模和电子显微镜来了解晶界对光激发电子和空穴行为（包括载流子传输）的影响和重组）。然而，我们还讨论了与可充电电池相关的材料，作为能源应用的另一类重要材料。我们通过讨论该领域的突出挑战以及未来几年令人兴奋的进展前景来结束审查。