The zero bandgap of graphene limits its utilization in optoelectronics. Quantum confinement in finite-size graphene structures, such as graphene quantum dots (GQDs) and holey GQDs, may offer a path for generating a wide range of HOMO-LUMO gaps. Edge terminations and pore passivations in these structures provide further means to alter their optical properties. In this work, we study the structural stabilities and optical properties of GQDs and holey GQDs with different sizes, edge terminations, and pore passivations, using density functional theory (DFT) as well as time dependent DFT. We find that the optical spectra of GQDs depend primarily on their size. Edge termination has a small influence on the spectra; shifting the absorption peaks by ~ 0.2 eV, which gets smaller for larger GQDs. Creation of pores in GQDs lead to the emergence of new peaks in their absorption spectra. Pore passivation seems to have the biggest effect on the absorption spectra of holey GQDs, while their termination leads to slight shifts in their peaks. Our results can be used to develop promising materials for many applications, such as biological sensors, and optoelectronic devices.

石墨烯的零带隙限制了其在光电子学中的利用。有限尺寸的石墨烯结构（例如石墨烯量子点（GQD）和多孔GQD）中的量子限制可能会提供一条生成广泛HOMO-LUMO间隙的途径。这些结构中的边缘终端和孔钝化提供了进一步改变其光学性能的方法。在这项工作中，我们使用密度泛函理论（DFT）和随时间变化的DFT，研究了具有不同尺寸，边缘终止和孔钝化的GQD和多孔GQD的结构稳定性和光学性质。我们发现GQD的光谱主要取决于它们的大小。边缘终止对光谱影响很小；将吸收峰移动约0.2 eV，对于较大的GQD，该值变小。GQD中孔的形成导致了其吸收光谱中新峰的出现。孔钝化似乎对有孔GQD的吸收光谱影响最大，而它们的终止会导致其峰的轻微移动。我们的结果可用于为许多应用开发有前途的材料，例如生物传感器和光电设备。