Circularly Polarized Light-Enabled Chiral Nanomaterials:From Fabrication to Application

For decades,chiral nanomaterials have been extensively studied because of their extraordinary properties.Chiral nanostructures have attracted a lot of interest because of their potential applications including biosensing,asymmetric catalysis,optical devices,and negative index materials.Circularly polarized light(CPL)is the most attractive source for chirality owing to its high availability,and now it has been used as a chiral source for the preparation of chiral matter.In this review,the recent progress in the field of CPL-enabled chiral nanomaterials is summarized.Firstly,the recent advancements in the fabrication of chiral materials using circularly polarized light are described,focusing on the unique strategies.Secondly,an overview of the potential applications of chiral nanomaterials driven by CPL is provided,with a particular emphasis on biosensing,catalysis,and phototherapy.Finally,a perspective on the challenges in the field of CPL-enabled chiral nanomaterials is given.

Self-powered circularly polarized light detector based on asymmetric chiral metamaterials

Circularly polarized light(CPL)has been given great attention because of its extensive application.While several devices for CPL detection have been studied,their performance is affected by the magnitude of photocurrent.In this paper,a self-powered photodetector based on hot electrons in chiral metamaterials is proposed and optimized.CPL can be distinguished by the direction of photocurrent without external bias owing to the interdigital electrodes with asymmetric chiral metamaterials.Distinguished by the direction of photocurrent,the device can easily detect the rotation direction of the CPL electric field,even if it only has a very weak responsivity.The responsivity of the proposed detector is near 1.9 mA/W at the wavelength of 1322 nm,which is enough to distinguish CPL.The detector we proposed has the potential for application in optical communication.

Detecting Spin Bias with Circularly Polarized Light

We theoretically study the spin transport through a two-terminal quantum dot device under the influence of a symmetric spin bias and circularly polarized light. It is found that the combination of the circularly polarized light and the applied spin bias can result in a net charge current. The resultant charge current is large enough to be measured when properly choosing the system parameters. The resultant charge current can be used to deduce the spin bias due to the fact that there exists a simple linear relation between them. When the external circuit is open, a charge bias instead of a charge current can be induced, which is also measurable by present technologies. These findings indicate a new approach to detect the spin bias by using circularly polarized light.

Circularly polarized light emission and detection by chiral inorganic semiconductors

Chiral inorganic semiconductors with high dissymmetric factor are highly desirable,but it is generally difficult to induce chiral structure in inorganic semiconductors because of their structure rigidity and symmetry.In this study,we introduced chiral ZnO film as hard template to transfer chirality to CsPbBr_(3) film and PbS quantum dots(QDs)for circularly polarized light(CPL)emission and detection,respectively.The prepared CsPbBr_(3)/ZnO thin film exhibited CPL emission at 520 nm and the PbS QDs/ZnO film realized CPL detection at 780 nm,featuring high dissymmetric factor up to around 0.4.The electron transition based mechanism is responsible for chirality transfer.

Absolute asymmetric synthesis driven by circularly polarized light

Circularly polarized light(CPL)is an inherently chiral entity and is regarded as one of the possible deterministic signals that led to the evolution of homochirality in earth.Thus,CPL as an external physical field has been widely used in a technique known as absolute asymmetric synthesis,because a product enriched in one enantiomer is formed from racemic precursor molecules without the intervention of a chiral catalyst.In this review,we retrospect the historical research of CPL-induced absolute asymmetric synthesis,including chiral organic molecules,helical polymers,supramolecular assemblies,noble metal nanostructures.However,based on these results,we concluded that the chiral photon-matter interaction is very faint due to the arrangement of molecular bonds giving rise to chiral features,is over a smaller distance than the helical pitch of CPL,leading extremely small enantiomeric excess for product.Therefore,we highlight the recently emerged technology called superchiral field,in which the superchiral far-field and near-field could enhance the dissymmetry of optical field and near-field,respectively.In sum,we hope this review could bring some enlightenment to researchers and further improve the enantioselectivity of CPL-induced absolute asymmetric synthesis.

Light-modulated graphene-based φ_(0) Josephson junction and -φ_(0) to φ_(0) transition

We investigate the chiral edge states-induced Josephson current–phase relation in a graphene-based Josephson junction modulated by the off-resonant circularly polarized light and the staggered sublattice potential.By solving the Bogoliubov–de Gennes equation,a φ_(0) Josephson junction is induced in the coaction of the off-resonant circularly polarized light and the staggered sublattice potential,which arises from the fact that the center of-mass wave vector of Cooper pair becomes finite and the opposite center of-mass wave vector to compensate is lacking in the nonsuperconducting region.Interestingly,when the direction of polarization of light is changed,-φ_(0) to φ_(0) transition generates,which generalizes the concept of traditional 0–πtransition.Our findings provide a purely optical way to manipulate a phase-controllable Josephson device and guidelines for future experiments to confirm the presence of graphene-based φ_(0)Josephson junction.

A Double Layer Laminated Film of Cellulose Nanocrystals and Dye Displaying Vibrant Circularly Polarized Light

Circularly polarized(CP)light is a circularly polarized electromagnetic wave and is of significance for applications,such as information storage and encryption,3D display and sensing due to its unique optical properties including optical information storage capacity and chiral specificity11-61.In order to produce circularly polarized light,chirality and light including spontaneous luminescence and incident light are necessary.

Delayed Fluorescence and Amplified Chirality via Modified Substitution Position for Deep-red Circularly Polarized Organic Light Emitting-diodes

Developing easily accessible deep-red/near-infrared circularly polarized emitters for practical organic light-emitting diodes remains a significant challenge.Here,a practical strategy has been proposed for developing deep-red circularly polarized delayed fluorescent emitters based on a novel chiral acceptor platform.By changing triphenylamine(TPA)substitution position from para to meta,R/S-M-TBBTCN demonstrated thermally activated delayed fluorescence(TADF)properties with a delayed lifetime of 6.6µs that R/S-P-TBBTCN doesn’t have.Furthermore,R/S-M-TBBTCN showed a 65 nm red-shift in emission and a 10-fold enhancement in asymmetry factor(glum),compared with R/S-P-TBBTCN.The solution-processed nondoped circularly polarized organic light-emitting diodes(CP-OLEDs)based on R-M-TBBTCN display deep-red emission and 2.2%external quantum efficiency.

Static Laser Light Scattering Studies from Red Blood Cells

A homemade Static Light scattering studies has been used to determine angle resolved scattered intensity for different polarization states of the incident laser light. Classical light scattering set ups are being used to study morphological aspects of scatterers using simple set ups using low power lasers. Red blood cells form rather interesting as well as a challenging system for scattering experiments. The scattering spectrometer consists of a scattering arm, a scattering turn table and collimating arm. Along with polarizers integrated in the collimating arm as well as scattering arms ensures collection of scattered flux with the required polarization state. This technique is being developed for its in vitro studies using fresh red blood cells. A brief review of the theoretical models used for scattering from Red Blood Cells (RBC) has been discussed in the paper. Scattering pattern (scattering plots) as well as polar plots of scattered flux have been determined for different polarization state of the incident light. Insight into the orientation of major axis of particles can be inferred from the polar plots.

Induced circularly polarized luminescence of perovskite nanocrystals by self-assembly chiral gel

Perovskites nanocrystals(NCs)with circularly polarized light(CPL)activity have drawn much attention due to the fascinating photoelectric properties of perovskite NCs as well as the abundant applications of CPL in three-dimensional(3D)displays,nonlinear optics,spintronics devices,CPL lasers,and so on.Herein,bio-inspired by life,we designed and synthesized a simple amphiphilic molecule which could self-assemble into chiral gel with helix chirality in non-polar solvents.Through co-assembly of the CsPbX3 NCs with the chiral gel,CPL at the first excitation band of CsPbX3 NCs is induced in the whole visible spectrum with a maximum glum of 8.2×10−3.The induced CPL arises from the selective CPL-absorption of the CsPbX3 NCs’luminesce by the chiral gel,which provides a facile and practical approach to induce CPL in perovskite NCs and other nanocrystals.

Host molecule enhanced aggregation induced emission of chiral silver nanoclusters for achieving highly efficient circularly polarized electroluminescence

Chiral metal nanoclusters(MNCs)are competitive candidates for fabricating circularly polarized light-emitting diodes(CPLEDs),but the device performance is greatly limited by the poor emission of MNCs in solid thin films.Herein,host molecule enhanced aggregation induced emission(AIE)of MNCs is demonstrated for fabricating highly efficient CPLEDs.Namely,on the basis of the AIE effect of atomically precise enantiomeric(R/S)-4-phenylthiazolidine-2-thione capped silver(R/S-Ag_(6)(PTLT)_(6))NCs in solid thin films,1,3-bis(carbazol-9-yl)benzene(mCP)is introduced as a host molecule to control the orientation and packing arrangements of R/S-Ag_(6)(PTLT)_(6) NCs throughπ–πinteractions with the R/S-Ag_(6)(PTLT)_(6) NCs and further enhance the AIE.The as-fabricated Ag_(6)(PTLT)_(6) NC/mCP hybrid solid thin film shows a high photoluminescence quantum yield of 71.0%close to that of Ag_(6)(PTLT)_(6) NC single crystal.As the hybrid films are employed as the active emission layers of CPLEDs,mCP also suppresses the triplettriplet annihilation and balances the charge transport.Thus,the CPLEDs exhibit a maximum brightness of 3,906 cd/m^(2),peak external quantum efficiency of 10.0%,electroluminescence dissymmetry factors of−5.3×10^(−3)and 4.7×10^(−3).

Chiral CdSe/CdS quantum dot (in rod)-light-emitting diodes with circularly polarized electroluminescence

Chiral quantum dot(in rod)-light-emitting diodes(CQLEDs)with circularly polarized electroluminescence(CPEL)have driven interest in the future display,communication,and storage industries.However,the preparation of CQLEDs is still a challenging unresolved.Herein,we fabricated CQLEDs through spin-coating evaporation of chiral CdSe/CdS quantum rods(CCCQs)colloidal solution on indium tin oxide substrate.The CCCQs were synthesized via an isotropically epitaxial growth with cholic acid as the symmetry breaking agent,which induced one-direction chiral dislocation around the c axis of their hexagonal crystal structure.The CCCQs were ranked side-by-side in right-handed chiral arrangement with helical axis perpendicular to substrate due to chiral driving force of the cholic acid arrangement.The CQLEDs exhibited a negative CPEL signal at 600 nm with a|gEL|of 2×10^(−4),which is ascribable to the selective filtration on emission arising from the circular Bragg resonance by quasi-photonic crystal structures.

Thermally activated delayed fluorescence materialsensitized helicene enantiomer-based OLEDs:a new strategy for improving the efficiency of circularly polarized electroluminescence

A new strategy of thermally activated delayed fluorescence(TADF)material-sensitized circularly polarized luminescence(CPL)has been proposed for improving the efficiencies of fluorescent circularly polarized organic lightemitting diodes(OLEDs)(CP-OLEDs).Consequently,a pair of helicene enantiomers,(P)-HAI and(M)-HAI,were synthesized.The helicene enantiomers with the rigid helicalπ-skeleton had highly thermal and enantiomeric stabilities,and they also showed excellent photophysical properties,especially,intense mirror-image CPL activities with large luminescence dissymmetry factor(|g_(lum)|)values of about 6×10^(-3).Notably,the CP-OLEDs with the helicene enantiomers as emitters and a TADF molecule as sensitizer not only displayed better performance of lower turn-on voltage(V_(T))of 2.6 V,four-fold maxmium-external quantum efficiency(EQE_(max))of 5.3%,and lower efficiencies roll-off of 1.9%at 1000 cd m^(-2),than those of the devices without TADF sensitizer,but also exhibited intense circularly polarized electroluminescence(CPEL)with the electroluminescence dissymmetry factor(g_(EL))values of-2.3×10^(-3)and+3.0×10^(-3).Meanwhile,this study also represents the first thermally activated sensitized fluorescent CP-OLEDs with markedly enhanced efficiencies and intense CPEL.

Chirality discerning and monitoring in a metal cladding optofluidic chip

The metabolic process of chiral drugs plays a significant role in clinics and in research on drugs.Here,we experimentally demonstrate by all-optical means that the chiral molecules can be quickly discriminated and monitored with the ultrahighorder modes excited in a metal cladding optofluidic chip,achieving over 5 times sensitivity with a low-dosage sample.We show that the varying concentration of the chiral drugs can be monitored both in cell and animal experiments,presenting a significant difference between chiral enantiomers at the optimal function time and the effect of the reaction.To our knowledge,this approach provides a new way to achieve important chiral discrimination for the pharmacokinetics and the pharmacodynamics and may present opportunities in indicating the health status of humans.