Emergent optoelectronic properties of two-dimensional junctions

Mario Hofmann^1*

¹Physics, NTU, Taipei, Taiwan

* Presenter:Mario Hofmann, email:mario@phys.ntu.edu.tw

2D materials junctions exhibit unique properties that arise from the strong light-matter interaction in their constituents and the intimate junction interface. In the simplest case of a 2D junction, a two-dimensional material is laterally surrounded by an air gap. We have demonstrated the efficient transduction of light into current in such as structure. Unlike traditional photosensors or solar cells, conversion proceeds through direct rectification of the light’s electric field as evidenced by clear polarization control and wavelength-dependent photovoltage [1]. Graphene-junction based rectennas showed a tenfold increase in photon-electron coupling over existing optical rectennas. The high efficiency and straightforward realization of 2D junction-based optoelectronics permit their extension to large networks of junctions. We have devised a simulation tool that can capture the complex carrier transport mechanism in such 2D junction assemblies and which predicts the occurrence of emergence – collective behavior that is not observed in individual members [2]. Such emergence is experimentally confirmed in lateral 2D all-carbon junction networks and enables wearable and ubiquitous sensors with unprecedented optoelectronic performance. Finally, a novel electrochemical deposition process is observed in graphene/graphene junctions and applied towards high-resolution decoration processes and neuromorphic devices.

References
[1] Nguyen, H.-T., Yen, Z.-L., Su, Y.-H., Hsieh, Y.-P., Hofmann, M., 2D Material-Enabled Optical Rectennas with Ultrastrong Light-Electron Coupling. Small 2022, 2202199.
[2] Yao, H., Hsieh, Y.P., Kong, J. and Hofmann, M., 2020. Modelling electrical conduction in nanostructure assemblies through complex networks. Nature Materials, 19(7), pp.745-751.
[3] Chen, D.R., Hofmann, M., Yao, H.M., Chiu, S.K., Chen, S.H., Luo, Y.R., Hsu, C.C. and Hsieh, Y.P., 2019. Lateral two-dimensional material heterojunction photodetectors with ultrahigh speed and

Keywords: 2D materials, heterojunctions, carrier transport, electrochemistry