In the present work we theoretically analyze electroluminescence occurring in a biased single-molecule junction with a chiral bridge imitated by a helical chain. We show that optical transitions between electron states of the chiral linker may result in the emission of circular polarized light whose handedness depends on both direction of propagation and the polarity of the bias voltage provided that the coupling between the bridge sites is sufficiently strong. The mechanism controlling this specific light emission does not depend on the magnetic moments and spin–orbit interactions. It rather relies on the chiral properties of the bridge molecule and on the distribution of the bias voltage between the electrodes in the junction.
more »
« less
Polariton ring currents and circular dichroism of Mg-porphyrin in a chiral cavity
By placing Mg-porphyrin molecules in a chiral optical cavity, time reversal symmetry is broken, and polariton ring currents can be generated with linearly polarized light, resulting in a circular dichroism signal. Since the electronic state degeneracy in the molecule is lifted by the formation of chiral polaritons, this signal is one order of magnitude stronger than the bare molecule signal induced by circularly polarized light. Enantiomer-selective photochemical processes in chiral optical cavities is an intriguing future possibility.
more »
« less
- Award ID(s):
- 1953045
- PAR ID:
- 10340545
- Date Published:
- Journal Name:
- Chemical Science
- Volume:
- 13
- Issue:
- 4
- ISSN:
- 2041-6520
- Page Range / eLocation ID:
- 1037 to 1048
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract For advancing next‐generation optoelectronics, a versatile strategy for fabricating π‐conjugated polymer (π‐CP)/chiral‐small molecule (SM) hybrid films through co‐crystallization‐mediated chirality transfer is reported. The transfer of optical chirality from 1,1′‐binaphthyl–2,2′‐diamine (BN), a representative chiral inducer SM, to thin films of various achiral π‐CPs, including non‐fluorene π‐CPs, is achieved by simply blending the π‐CPs with BN using aromatic organic solvents. The resulting π‐CP/chiral‐SM hybrid films exhibit chiroptical responses at the main electronic absorption bands of various π‐CPs. Studies of the morphology, crystalline structure, and phase‐separation structure of a representative hybrid system of poly(3‐hexylthiophene) (P3HT) and BN reveal that these hybrid films exhibit a characteristic lamellar structure where the π‐CPs co‐crystallize with chiral BN molecules, facilitated by aromatic solvent‐assisted intermolecular π–π interactions. In‐depth photophysical analysis suggests that BN molecules co‐crystallized in the P3HT lamellar structure induce asymmetrically misaligned transition dipoles along the P3HT conjugated backbone, transferring optical chirality from BN to P3HT under circularly polarized light illumination. As a proof‐of‐concept, chiroptical photodiodes based on π‐CP/chiral‐SM hybrid films and printed micropatterns, exhibiting a distinguishable photocurrent response depending on the direction of circularly polarized light are successfully demonstrated.more » « less
-
Circular dichroism (CD) spectroscopy, which measures the differential absorption of circularly polarized light with opposite handedness, is an important technique to detect and identify chiral molecules in chemistry, biology and life sciences. However, CD signals are normally very small due to the intrinsically weak chirality of molecules. Here we theoretically investigate the generation of chiral hotspots in silicon nanocube dimers for CD enhancement. Up to 15-fold enhancement of the global optical chirality is obtained in the dimer gap, which boosts the CD signal by one order of magnitude without reducing the dissymmetry factor. This chiral hotspot originates from the simultaneous enhancement of magnetic and electric fields and their proper spatial overlap. Our findings could lead to integrated devices for CD spectroscopy, enantioselective sensing, sorting and synthesis.more » « less
-
: Chiral inorganic nanostructures strongly interact with photons changing their polarization state. The resulting circularly polarized light emission (CPLE) has cross-disciplinary importance for a variety of chemical/biological processes and is essential for development of chiral photonics. However, the polarization effects are often complex and could be misinterpreted. CPLE in nanostructured media has multiple origins and several optical effects are typically convoluted into a single output. Analysing CPLE data obtained for nanoclusters, NPs, nanoassemblies, and nanocomposites from metals, chalcogenides, perovskite, and other nanostructures, we show that there are several distinct groups of nanomaterials for which CPLE is dominated either by circularly polarized luminescence (CPL) or circularly polarized scattering (CPS); there are also many nanomaterials for which they are comparable. We also show that (1) CPL and CPS contributions involve light-matter interactions at different structural levels; (2) contribution from CPS is especially strong for nanostructured microparticles, nanoassemblies and composites; and (3) engineering of materials with strongly polarized light emission requires synergistic implementation of CPL and CPS effects. These findings are expected to guide development of CPLE materials in a variety of technological fields, including 3D displays, information storage, biosensors, optical spintronics, and biological probes.more » « less
-
Plasmonic nanoparticles with chiral resonances in the visible wavelengths complement optical dissymmetry in the ultraviolet and near-infrared wavelengths in natural products and metamaterials respectively. Here, we show that under oxidative conditions, hot holes photogenerated with circularly polarized light in gold nanoprisms can spatially direct the photodeposition of lead oxide (PbO2), resulting in chiral nanostructures tunable with the polarization and wavelength of light. We observe a g-factor of 3.6 × 10–3, which can be attributed to the enhanced optical dissymmetry with PbO2 deposition of the side of nanoprisms upon illumination with green 532 nm light. Our finite-difference time-domain calculations support the site-specific photodeposition of PbO2 onto nanoprisms. This work shows that plasmonic nanoparticles can have tunable chiral properties imbued as a function of the wavelength and polarization of light.more » « less
An official website of the United States government

