To produce and characterize 2D materials at large scale as well as to control and utilize unique local properties, we need methods that can quantitatively and rapidly analyze 2D materials with ability to reveal local properties, such as domain boundaries. In this presentation, we report a transient absorption (TA) imaging method for fast visualization, quantitative layer analysis of graphene and mapping of grain boundaries in ambient condition. Images created based on different density of states at boundaries through TA intensity and carrier dynamics through TA decay at each pixel both mapped the grain boundaries in graphene. We have further improved the imaging speed by line-illumination and paralleled heterodyne detection and achieved an unprecedented 1,000 frames per second imaging speed. Our method enabled time-resolved transient absorption imaging at a speed of 50 frames per second, which is 100 times faster than the state-of-the-art. Using this method, we demonstrated a real-time non-destructive characterization of graphene in conditions that mimic the roll-to-roll manufacturing process at a rolling speed of 0.3 m/min. In addition, real-time TA imaging of graphene oxide in vitro with capability of quantitative analysis of intracellular concentration and ex vivo in circulating blood were demonstrated. These results suggest that TA microscopy is a valid tool for the study of graphene based materials. Our study opens new opportunities to image other 2D materials including polymer-based thin-films, in vivo medical diagnosis, as well as monitoring the dynamics of biomolecules in living systems.

Highly sensitive and high-speed imaging of grain boundaries in graphene by transient absorption microscopy

256th National Meeting (2018)

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