Song Seunghyun, Kim Hyeongmun, Kang Chul, Bae Joonho
Department of Physics, Gachon University, 1342 Seongnamdaero, Sujeong-gu, Seongnam 13120, Republic of Korea.
Department of Physics, Chonnam National University, 77 Yongbong-ro, Buk-gu, Gwangju 61186, Republic of Korea.
Nanomaterials (Basel). 2023 Jun 27;13(13):1948. doi: 10.3390/nano13131948.
Graphene quantum dots (GQDs) with a band gap have been widely applied in many fields owing to their unique optical properties. To better utilize the optical advantages of GQDs, it is important to understand their optical characteristics. Our study demonstrates the optical properties and carrier behaviors of synthesized graphene oxide quantum dot (GOQD) and reduced graphene oxide quantum dot (rGOQD) pellets via Terahertz time-domain spectroscopy (THz-TDS). The complex permittivity and optical conductivity are obtained in the terahertz region, indicating that the optical conductivity of the GOQD is higher than that of the rGOQD. Although rGOQD has a higher carrier density, approximately 1.5-times than that of GOQD, the lower charge carrier mobility of the rGOQD, which is obtained using Drude-Lorentz oscillator model fitting contributes to a decrease in optical conductivity. This lower mobility can be attributed to the more significant number of defect states within the rGOQD compared to GOQD. To the best of our knowledge, our study initially demonstrates the optical property and carrier behaviors of GOQD and rGOQD in the THz region. Moreover, this study provides important information on factors influencing carrier behavior to various fields in which carrier behavior plays an important role.
具有带隙的石墨烯量子点（GQDs）因其独特的光学性质而在许多领域得到广泛应用。为了更好地利用GQDs的光学优势，了解其光学特性非常重要。我们的研究通过太赫兹时域光谱（THz-TDS）展示了合成的氧化石墨烯量子点（GOQD）和还原氧化石墨烯量子点（rGOQD）颗粒的光学性质和载流子行为。在太赫兹区域获得了复介电常数和光导率，表明GOQD的光导率高于rGOQD。尽管rGOQD具有更高的载流子密度，约为GOQD的1.5倍，但使用德鲁德-洛伦兹振荡器模型拟合得到的rGOQD较低的电荷载流子迁移率导致光导率降低。这种较低的迁移率可归因于与GOQD相比，rGOQD中存在更多数量的缺陷态。据我们所知，我们的研究首次展示了GOQD和rGOQD在太赫兹区域的光学性质和载流子行为。此外，本研究为载流子行为起重要作用的各个领域提供了有关影响载流子行为因素的重要信息。
