Increased Work Function in Few-Layer Graphene Sheets via Metal Chloride Doping
Increased Work Function in Few-Layer Graphene Sheets via Metal Chloride Doping
复制标题
DOI：
10.1002/adfm.201200997
复制
发表时间：
2012-11-21
影响因子：
19
通讯作者：
Kim, Soo Young
中科院分区：
文献类型：
--
作者：
Kwon, Ki Chang;Choi, Kyoung Soon;Kim, Soo Young
研究了一种控制少层石墨烯功函数的化学方法。采用化学气相沉积法在铜箔上制备了石墨烯薄膜。六种金属氯化物AuCl 3、IrCl 3、MoCl 3、OsCl 3、PdCl 2和RhCl 3用作掺杂剂。由于金属颗粒的形成，掺杂的石墨烯的薄层电阻从1100 Ω/sq降低到约500 Ω/sq，并且对于20 mM AuCl 3，其在550 nm处的透射率也从96.7%降低到93%。随着金属氯化物浓度的增加，薄层电阻和透射率降低。在金属氯化物掺杂后，拉曼光谱中的G峰向更高的波数移动，这表明从石墨烯到金属离子的电荷转移。IC的强度比？C/IC-C随着掺杂而增加，表明电子从石墨烯片转移到金属离子。紫外光电子能谱数据显示，对于具有20 mM AuCl 3、IrCl 3、MoCl 3、OsCl 3、PdCl 2和RhCl 3的石墨烯，石墨烯的功函数分别从4.2 eV增加到5.0、4.9、4.8、4.68、5.0和5.14 eV。据认为，从石墨烯的特定能级到金属离子发生自发电荷转移，从而增加功函数。
A chemical approach to controlling the work function of few-layer graphene is investigated. Graphene films are synthesized on Cu foil by chemical vapor deposition. Six metal chlorides, AuCl3, IrCl3, MoCl3, OsCl3, PdCl2, and RhCl3, are used as dopants. The sheet resistance of the doped graphene decreases from 1100 Omega/sq to approximate to 500700 Omega/sq and its transmittance at 550 nm also decreases from 96.7% to 93% for 20 mM AuCl3 due to the formation of metal particles. The sheet resistance and transmittance are reduced with increasing metal chloride concentration. The G peak in the Raman spectra is shifted to a higher wavenumber after metal chloride doping, which indicates a charge transfer from graphene to metal ions. The intensity ratio of IC?C/IC-C increases with doping, indicating an electron transfer from graphene sheets to metal ions. Ultraviolet photoemission spectroscopy data shows that the work function of graphene increases from 4.2 eV to 5.0, 4.9, 4.8, 4.68, 5.0, and 5.14 eV for the graphene with 20 mM AuCl3, IrCl3, MoCl3, OsCl3, PdCl2, and RhCl3, respectively. It is considered that spontaneous charge transfer occurs from the specific energy level of graphene to the metal ions, thus increasing the work function.