J. Heyrovsky Institute of Physical Chemistry of the CAS, v.v.i., Dolejskova 2155/3, 182 23 Prague 8, Czech Republic.
Phys Chem Chem Phys. 2019 Nov 27;21(46):25700-25706. doi: 10.1039/c9cp04993b.
The efficient manipulation of the optoelectronic properties of layered semiconductors is essential for future applications of these unique materials. Here, we demonstrate that single-layer, large-area graphene can serve as a conductive spacer between an electrolyte solution and single-layer MoS2. In situ Raman and photoluminescence (PL) spectroscopies were employed to monitor the charge transfer from graphene to MoS2. The Raman G and 2D bands were used to quantify the carrier concentration in graphene. The high efficiency of the charge transfer via graphene in a broad carrier concentration range of ±2.1 × 1013 cm-2 was documented by the extreme sensitivity of the MoS2 Raman mode to the electron-doping (shift rate of ∼2.5 cm-1/1 × 1013 cm-2 electron concentration) and the high sensitivity of the PL yield, which drops by more than one and two orders of magnitude in the hole and electron doping regimes, respectively. The easy implementation, and the lithography-free effectiveness of the setup, in terms of the achievable carrier concentration range and the charge-transfer efficiency, could be an asset in near-future research and in the development of optoelectronic devices.
高效地操控层状半导体的光电性能对于这些独特材料的未来应用至关重要。在这里，我们证明了单层、大面积石墨烯可以作为电解质溶液和单层 MoS2 之间的导电间隔物。我们采用原位拉曼和光致发光（PL）光谱来监测从石墨烯到 MoS2 的电荷转移。拉曼 G 和 2D 带用于量化石墨烯中的载流子浓度。通过石墨烯在 ±2.1×1013cm-2 的宽载流子浓度范围内实现高效电荷转移，这通过 MoS2 拉曼模式对电子掺杂的极端敏感性（约 2.5cm-1/1×1013cm-2 电子浓度的位移率）和 PL 产率的高灵敏度得到证明，在空穴和电子掺杂区，PL 产率分别下降了一个和两个数量级以上。从可实现的载流子浓度范围和电荷转移效率来看，该设置易于实施且无需光刻，这可能是近期研究和光电设备开发的一个优势。
