RESUMEN
Molecular electronics is a promising route for down-sizing electronic devices. Tip-enhanced Raman spectroscopy provides us a setup to probe current-driven molecular junctions that are considered as prototypes of molecular electronic devices. In this setup, the plasmonic tip concentrates optical fields to a degree that allows observing optical response of single molecules. Simultaneously, the tip can also induce a localized optical angular momentum, which has been seldomly considered in previous studies. Here, we propose that the induced optical angular momentum can interact with the probed molecule and strongly modify the response signal. Specifically, we demonstrate the ability to control the vibrational resonance of current-driven molecular junctions with the optical angular momentum. This precise control of light-matter interactions at the nanoscale allows us to demonstrate multiple logic operations. These results provide a fundamental understanding of future molecular electronics applications.
RESUMEN
Crystal engineering is a practical approach for tailoring material properties. This approach has been widely studied for modulating optical and electrical properties of semiconductors. However, the properties of organic molecular crystals are difficult to control following a similar engineering route. In this Letter, we demonstrate that engineered crystals of Alq3 and Ir(ppy)3 complexes, which are commonly used in organic light-emitting technologies, possess intriguing functional properties. Specifically, these structures not only process efficient low-energy induced triplet excitation directly from the ground state of Alq3 but also can show strong emission at the Alq3 triplet energy level at room temperatures. We associate these phenomena with local deformations of the host matrix around the guest molecules, which in turn lead to a stronger host-guest triplet-triplet coupling and spin-orbital mixing.