Lee Kimin, Kil Juneyoung, Park JaeWoo, Yang Sui, Park Byoungchoo
Department of Electrical and Biological Physics, Kwangwoon University, Wolgye-Dong, Seoul 01897, Republic of Korea.
Materials Science and Engineering, School for Engineering of Matter Transport and Energy, Arizona State University, Tempe, AZ 85287, USA.
Polymers (Basel). 2025 Mar 4;17(5):689. doi: 10.3390/polym17050689.
The removal of surface residues from single-layer graphene (SLG), including poly(methyl methacrylate) (PMMA) polymers and Cl ions, during the transfer process remains a significant challenge with regard to preserving the intrinsic properties of SLG, with the process often leading to unintended doping and reduced electronic performance capabilities. This study presents a rapid and efficient surface treatment method that relies on an aqueous sodium nitrite (NaNO) solution to remove such contaminants effectively. The NaNO solution rinse leverages reactive nitric oxide (NO) species to neutralize ionic contaminants (e.g., Cl) and partially oxidize polymer residues in less than 10 min, thereby facilitating a more thorough final cleaning while preserving the intrinsic properties of graphene. Characterization techniques, including atomic force microscopy (AFM), Kelvin probe force microscopy (KPFM), and X-ray photoelectron spectroscopy (XPS), demonstrated substantial reductions in the levels of surface residues. The treatment restored the work function of the SLG to approximately 4.79 eV, close to that of pristine graphene (~4.5-4.8 eV), compared to the value of nearly 5.09 eV for conventional SLG samples treated with deionized (DI) water. Raman spectroscopy confirmed the reduced doping effects and improved structural integrity of the rinsed SLG. This effective rinsing process enhances the reproducibility and performance of SLG, enabling its integration into advanced electronic devices such as organic light-emitting diodes (OLEDs), photovoltaic (PV) cells, and transistors. Furthermore, the technique is broadly applicable to other two-dimensional (2D) materials, paving the way for next-generation (opto)electronic technologies.
在转移过程中，从单层石墨烯（SLG）中去除表面残留物，包括聚甲基丙烯酸甲酯（PMMA）聚合物和氯离子，对于保留SLG的固有特性而言仍然是一项重大挑战，因为该过程常常会导致意外的掺杂并降低电子性能。本研究提出了一种快速有效的表面处理方法，该方法依靠亚硝酸钠（NaNO₂）水溶液来有效去除此类污染物。NaNO₂溶液冲洗利用活性一氧化氮（NO）物种在不到10分钟的时间内中和离子污染物（如Cl⁻）并部分氧化聚合物残留物，从而在保留石墨烯固有特性的同时便于进行更彻底的最终清洁。包括原子力显微镜（AFM）、开尔文探针力显微镜（KPFM）和X射线光电子能谱（XPS）在内的表征技术表明，表面残留物水平大幅降低。与用去离子水（DI）处理的传统SLG样品的近5.09 eV的值相比，该处理将SLG的功函数恢复到约4.79 eV，接近原始石墨烯的值（约4.5 - 4.8 eV）。拉曼光谱证实了冲洗后的SLG的掺杂效应降低且结构完整性得到改善。这种有效的冲洗过程提高了SLG的可重复性和性能，使其能够集成到诸如有机发光二极管（OLED）、光伏（PV）电池和晶体管等先进电子器件中。此外，该技术广泛适用于其他二维（2D）材料，为下一代（光）电子技术铺平了道路。
