Developing characterization strategies to better understand nanoscale features in two-dimensional nanomaterials is of crucial importance, as the properties of these materials are many times driven by nanoscale and microscale chemical and structural modifications within the material. For the case of large area monolayer MoSe₂ flakes, kelvin probe force microscopy coupled with tip-enhanced photoluminescence was utilized to evaluate such features including internal grain boundaries, edge effects, bilayer contributions, and effects of oxidation/aging, many of which are invisible to topographical mapping. A reduction in surface potential due to n-type behavior was observed at the edge of the flakes as well as near grain boundaries. Potential phase mapping, which corresponds to the local dielectric constant, depicted local biexciton and trion states in optically-active regions of interest such as grain boundaries. Finally, nanoscale surface potential and photoluminescence mapping was performed at several stages of oxidation, revealing that various oxidative states can be evaluated during the aging process. Importantly, all of the characterization performed in this study was non-destructive and rapid, crucial for quality evaluation of an exciting class of two-dimensional nanomaterials.

开发更好地理解二维纳米材料中纳米级特征的表征策略至关重要，因为这些材料的性能通常受材料中纳米级和微米级化学和结构修饰的驱动。对于大面积单层MoSe ₂薄片，采用开尔文探针力显微镜和尖端增强的光致发光技术来评估这些特征，包括内部晶界，边缘效应，双层贡献以及氧化/老化效应，其中许多是不可见的到地形图。由于n导致表面电势降低在薄片的边缘以及靠近晶界处观察到-型行为。对应于局部介电常数的位相映射描述了感兴趣的光学活性区域（如晶界）中的局部双激子和三重子态。最后，在氧化的几个阶段进行了纳米级表面电势和光致发光映射，揭示了在老化过程中可以评估各种氧化态。重要的是，在这项研究中进行的所有表征都是无损且快速的，对于激动人心的二维纳米材料类别的质量评估至关重要。