In this paper, a brand new structure based on graphene quantum dots (GQDs) is introduced which is doped with two selenium atoms and functionalized with amino groups simultaneously. The purpose of the structure is to achieve a photoluminescence (PL) spectrum which peaks at free-space communication wavelengths range. Hence, using density functional theory (DFT), time-dependent DFT (TD-DFT) calculations and analyzing charge density distribution, the density and the energy of molecular orbitals and dominant electronic transitions, the energy and the wavelength for dominant excited states and also the density of states (DOS) diagram for pure GQD, selenium-doped GQD and simultaneously doped and functionalized GQD is discussed. PL spectrum of the device is obtained for each three structures. Studying precisely all the mechanisms which affect PL spectrum, it is understood that selenium doping with graphitic configuration by inducing an electrical dipole moment to the structure leads to increasing charge density in π and π^* orbitals at doped regions. Moreover, by decreasing the gap between dominant transitions, it shifts the PL spectrum peak from 484.4 to 520 nm. After functionalizing the doped structure with NH₂ groups with a configuration which is close to the structure that will be obtained at real synthesis conditions and also analyzing the dominant states and DOS diagram, it can be figured out that not only a large electrical dipole moment is induced, but also some new inter-band states are formed within the band gap and these new states improve the interactions between charge carrier transitions in the structure just like the inter band trap levels in optical electronics. In addition, they increase the hybridization between the orbitals and also decrease the gap between dominant transitions and thus the PL spectrum peak will shift to 760 nm.

本文介绍了一种基于石墨烯量子点（GQD）的全新结构，该结构掺杂了两个硒原子并同时被氨基官能化。该结构的目的是实现在自由空间通信波长范围内达到峰值的光致发光（PL）光谱。因此，使用密度泛函理论（DFT），时变DFT（TD-DFT）计算并分析电荷密度分布，分子轨道和主电子跃迁的密度和能量，主激发态的能量和波长，以及讨论了纯GQD，硒掺杂GQD以及同时掺杂和功能化GQD的状态密度（DOS）图。对于每三个结构，获得器件的PL光谱。仔细研究影响PL频谱的所有机制，掺杂区的π和π ^*轨道。此外，通过减小主要跃迁之间的间隙，它将PL谱峰从484.4移至520 nm。用NH ₂对掺杂结构进行功能化后这些基团的结构接近于在实际合成条件下将获得的结构，并且还分析了主导态和DOS图，因此可以看出，不仅诱发了大的电偶极矩，而且还产生了一些新的互偶极矩。在带隙内形成能带状态，这些新状态改善了结构中电荷载流子跃迁之间的相互作用，就像光电子学中的带间陷阱能级一样。另外，它们增加了轨道之间的杂交，也减小了主要跃迁之间的间隙，因此PL光谱峰将移至760 nm。