Two-dimensional group-VI transition metal dichalcogenide semiconductors, such as MoS₂, WSe₂, and others, exhibit strong light-matter coupling and possess direct band gaps in the infrared and visible spectral regimes, making them potentially interesting candidates for various applications in optics and optoelectronics. Here, we review their optical and optoelectronic properties with emphasis on exciton physics and devices. As excitons are tightly bound in these materials and dominate the optical response even at room-temperature, their properties are examined in depth in the first part of this article. We discuss the remarkably versatile excitonic landscape, including bright, dark, localized and interlayer excitons. In the second part, we provide an overview on the progress in optoelectronic device applications, such as electrically driven light emitters, photovoltaic solar cells, photodetectors, and opto-valleytronic devices, again bearing in mind the prominent role of excitonic effects. We conclude with a brief discussion on challenges that remain to be addressed to exploit the full potential of transition metal dichalcogenide semiconductors in possible exciton-based applications.

二维VI族过渡金属_二硫化氢半导体，例如MoS ₂，WSe ₂，以及其他一些器件，表现出很强的光-质耦合，并且在红外和可见光谱范围内具有直接的带隙，使其成为光学和光电子学中各种应用的潜在候选者。在这里，我们将重点介绍激子物理和器件，研究它们的光学和光电特性。由于激子紧密地结合在这些材料中，并且即使在室温下也能控制光学响应，因此本文第一部分深入研究了激子的特性。我们讨论了非常多才多艺的激子景观，包括明亮，黑暗，局部和层间激子。在第二部分中，我们概述了光电器件应用的进展，例如电动发光器，光伏太阳能电池，光电探测器和光电电子器件，再次牢记激子效应的突出作用。最后，我们简要讨论了在可能的基于激子的应用中充分利用过渡金属二卤化半导体所具有的潜力，尚需解决的挑战。