Single-molecule optoelectronic devices: physical mechanism and beyond

Single-molecule devices not only promise to provide an alternative strategy to break through the miniaturization and functionalization bottlenecks faced by traditional semiconductor devices, but also provide a reliable platform for exploration of the intrinsic properties of matters at the single-molecule level. Because the regulation of the electrical properties of single-molecule devices will be a key factor in enabling further advances in the development of molecular electronics, it is necessary to clarify the interactions between the charge transport occurring in the device and the external fields, particularly the optical field. This review mainly introduces the optoelectronic effects that are involved in single-molecule devices, including photoisomerization switching, photoconductance, plasmon-induced excitation, photovoltaic effect, and electroluminescence. We also summarize the optoelectronic mechanisms of single-molecule devices, with particular emphasis on the photoisomerization, photoexcitation, and photo-assisted tunneling processes. Finally, we focus the discussion on the opportunities and challenges arising in the single-molecule optoelectronics field and propose further possible breakthroughs.