System on Chip Chemical Process Research Center, Department of Chemical Engineering, Pohang University of Science and Technology, Pohang 790-784, South Korea.
ACS Appl Mater Interfaces. 2013 Feb;5(3):822-7. doi: 10.1021/am3023898. Epub 2013 Jan 29.
We report electrical measurements of films of carbon quantum dots (CQDs) that serve as the channels of field-effects transistors (FETs). To investigate the dependence of the field-effect mobility on ligand length, colloidal CQDs are synthesized and ligand-exchanged with several primary amines of different ligand lengths. We measure current as a function of gate voltage and find that the devices show ambipolar conductivity, with electron and hole mobilities as high as 8.49 × 10(-5) and 3.88 × 10(-5) cm(2) V(-1) s(-1), respectively. The electron mobilities are consistently 2-4 times larger than the hole mobilities. Furthermore, the mobilities decrease exponentially with the increase of the ligand length, which is well-described by the Miller-Abrahams model for nearest-neighbor hopping. Our results provide a theoretical basis to examine charge transport in CQD films and offer new prospects for the fabrication of high-mobility CQD-based optoelectronic devices, including solar cells, light-emitting devices, and optical sensors.
我们报告了碳量子点（CQD）薄膜的电学测量结果，这些薄膜可用作场效应晶体管（FET）的通道。为了研究场效应迁移率对配体长度的依赖性，我们合成了胶体 CQD，并将其与几种不同配体长度的伯胺进行配体交换。我们测量了电流随栅极电压的变化，发现器件表现出双极性导电性，电子和空穴迁移率高达 8.49×10^-5 和 3.88×10^-5 cm^2 V^-1 s^-1。电子迁移率始终比空穴迁移率大 2-4 倍。此外，迁移率随配体长度的增加呈指数衰减，这很好地符合了 Miller-Abrahams 近邻跳跃模型。我们的研究结果为研究 CQD 薄膜中的电荷输运提供了理论基础，并为制造基于 CQD 的高迁移率光电设备，包括太阳能电池、发光器件和光学传感器提供了新的前景。
