Currently, the development of circularly polarized luminescent (CPL) materials has drawn extensive attention due to the numerous potential applications in optical data storage, displays, backlights ...in 3D displays, and so on. While the fabrication of CPL‐active materials generally requires chiral luminescent molecules, the introduction of the “self‐assembly” concept offers a new perspective in obtaining the CPL‐active materials. Following this approach, various self‐assembled materials, including organic‐, inorganic‐, and hybrid systems can be endowed with CPL properties. Benefiting from the advantages of self‐assembly, not only chiral molecules, but also achiral species, as well as inorganic nanoparticles have potential to be self‐assembled into chiral nanoassemblies showing CPL activity. In addition, the dissymmetry factor, an important parameter of CPL materials, can be enhanced through various pathways of self‐assembly. Here, the present status and progress of self‐assembled nanomaterials with CPL activity are reviewed. An overview of the key factors in regulating chiral emission materials at the supramolecular level will largely boost their application in multidisciplinary fields.
Recent development of circularly polarized luminescent (CPL) materials has aroused extensive attention. The self‐assembly strategy is proposed to address the barriers of tedious syntheses and the restricted substitutes during the development of CPL‐active materials. By highlighting the meritorious findings, the present status and progress in this field are reviewed, with the aim of boosting the development of chiroptical materials.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
A chiral zeolitic imidazolate framework (ZIF) showing circularly polarized luminescence (CPL) has been successfully constructed by blending binapthyl‐derived chiral emitters with ZIF‐8 rhombic ...dodecahedron nanoparticles. This approach solves a major trade‐off in CPL‐active materials: the large luminescence dissymmetry factor (glum) always suffers from suppression of luminescence efficiency. Compared to the optical properties of chiral emitters, the obtained chiral ZIF nanomaterials showed an enhanced fluorescence efficiency while the |glum| value is significantly amplified by one order of magnitude. Additionally, enantioselective fluorescence sensing in response to α‐hydroxycarboxylic acids has been enhanced in chiral ZIFs. Reorganization and conjunction of chiral emitters to the skeleton of ZIF nanoparticles can greatly improve both the luminescence quantum yield and circularly polarization, which facilitates the design of more efficient chiroptical materials.
Knowing their left from right: A chiral zeolitic imidazolate framework showing circularly polarized luminescence has been successfully constructed. It can be used as an enantioselective fluorescence sensor for α‐hydroxycarboxylic acids.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Upconverted circularly polarized luminescence (UCPL) processes have attracted great interest, because the chiroptical properties could be expressed in different photophysical processes. In this ...Letter, the first example of two-photon absorption-based upconverted circularly polarized luminescence (TP-UCPL) is demonstrated. The chiral α-octylamine-modified cesium lead bromides perovskite nanocrystals exhibited TP-UCPL with a two-photon absorption cross section at 800 nm (σ2,800 nm) up to 3.68 × 104 GM and luminescence dissymmetric factor (g lum) up to 7.0 × 10–3. Depending on the molecular chirality of the capping ligands, the TP-UCPL sense can be selected and the mirror-imaged CPL is obtained. It is envisaged that this approach will afford a new viewpoint for designing UCPL processes.
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IJS, KILJ, NUK, PNG, UL, UM
Circularly polarized luminescent materials have reached a thriving stage due to their potential applications in various research fields. However, the most important parameter of circularly polarized ...luminescence, luminescence dissymmetry factor (
g
lum
), is unsatisfactory to date, particularly for organic small molecules. Thus, obtaining large
g
lum
values is an emergent and critical challenge in the CPL research field, and various strategies have consequently been proposed, including supramolecular self-assembly or co-assembly, energy transfer or charge transfer hybrid chiral systems, aggregation-induced emission chiral luminophores, and so forth. Nevertheless, among all these strategies, chiral nematic liquid crystals (N*LCs) possess incomparable advantages in acquiring high
g
lum
values, because of their unique optical properties and excellent generality. In this review, we systematically review the recent progress of CPL-active N*LCs and provide a short perspective on their further applications. We envisage that N*LCs will play a more and more important role in the CPL research field and this review will attract more researchers to this field.
Chiral nematic liquid crystals exhibit excellent performance in obtaining high luminescence dissymmetry factor of circularly polarized luminescence.
Abstract
Existing circularly polarized luminescence materials can hardly satisfy the requirements of both large luminescence dissymmetry factor and high luminescent quantum yield, which hinders their ...practical applications. Here, we present a soft photonic crystal film embedded with chiral nanopores that possesses excellent circularly polarized luminescence performance with a high luminescence dissymmetry factor as well as a large luminescent quantum yield when loaded with various luminescent dyes. Benefitting from the retention of chiral nanopores imprinted from a chiral liquid crystal arrangement, the chiral soft photonic crystal film can not only endow dyes with chiral properties, but also effectively avoid severe aggregation of guest dye molecules. More importantly, the soft photonic crystal film can be recycled many times by loading and eluting guest dye molecules while retaining good stability as well as circularly polarized luminescence performance, enabling various applications, including smart windows, multi-color circularly polarized luminescence and anticounterfeiting.
A general phenomenon about upconverted circularly polarized luminescence (UC-CPL) based on triplet–triplet annihilation (TTA) was realized in an ambient environment by coupling three kinds of chiral ...acceptors with corresponding achiral sensitizers. All of the dissymmetry factors of UC-CPL exhibited significant amplification compared with the prompt CPL of the used chiral acceptors. Chirality-induced spin polarization during the TTA-UC process was in charge of the amplified dissymmetry factor of UC-CPL. Chirality-induced spin-polarized triplet excitons will suppress the TTA efficiency because the spin-polarized electrons go against the electron exchange within triplet excitons. However, the chirality-induced spin-polarized singlet excitons resulting from the TTA process can be promoted, enabling a large dissymmetry factor of UC-CPL.
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IJS, KILJ, NUK, PNG, UL, UM
The development of circularly polarized luminescence (CPL)-active materials with both large luminescence dissymmetry factor (g
) and high emission efficiency continues to be a major challenge. Here, ...we present an approach to improve the overall CPL performance by integrating triplet-triplet annihilation-based photon upconversion (TTA-UC) with localized surface plasmon resonance. Dye-loaded chiral micelles possessing TTA-UC ability are designed and attached on the surface of achiral gold nanorods (AuNRs). The longitudinal and transversal resonance peaks of AuNRs overlap with the absorption and emission of dye-loaded chiral micelles, respectively. Typically, 43-fold amplification of g
value accompanied by 3-fold enhancement of upconversion are obtained simultaneously when Au@Ag nanorods are employed in the composites. More importantly, transient absorption spectra reveal a fast accumulation of spin-polarized triplet excitons in the composites. Therefore, the enhancement of chirality-induced spin polarization should be in charge of the amplification of g
value. Our design strategy suggests that combining plasmonic nanomaterials with chiral organic materials could aid in the development of chiroptical nanomaterials.
Owing to its unique ability to efficiently convert low-energy photons into high-energy photons, triplet-triplet annihilation (TTA) based photon upconversion is a promising strategy for harvesting the ...low-energy tail of the solar spectrum for photovoltaic technologies. However, breaking through the upconversion quantum efficiency is not easy due to the few examples of existing annihilators that maximize the efficiency of singlet generation by TTA. Here, we present a new bichromophoric annihilator (PCP) that is paired with a metallic porphyrin as a sensitizer in low viscosity solution, and the system shows a record red-to-green external upconversion yield of 42%. This value can be achieved thanks to the photophysical properties of PCP that allow achieving a unitary triplet-to-singlet conversion efficiency and to its structural features that enable high fluorescence yields even at high concentrations.
An external efficiency of triplet-triplet annihilation based photon upconversion of up to 0.42 was achieved from bichromophoric annihilators sensitized by a metallic porphyrin sensitizer.
The general approach for fabricating solid-state materials showing circularly polarized luminescence (CPL) is still in its challenge. In this work, chiral metal-organic frameworks (MOFs) with ...full-color and white-color circularly polarized light emission are firstly achieved through a host-guest emitter-loading strategy. Chiral zeolitic imidazolate frameworks (ZIFs, a class of MOFs) are fabricated by a facile and simple mixed-ligand coassembly pathway. Meantime, achiral dyes, quantum dots (QDs), and upconversion nanoparticles (UCNPs) are easily loaded into the chiral ZIFs during the synthetic process. Size-matched dyes can be solely encapsulated into the chiral cages of ZIF, resulting in induced CPL and enhanced luminescence efficiency in solid-state ZIF⊃dye composites. Large-sized QDs, after embedding into the gap of the ZIF particles, also exhibited intense CPL activity. Furthermore, through modulating the blending ratio of colored dyes or QDs in chiral ZIFs, white light-emitting ZIFs with circular polarization could be constructed in a solid state. In addition, through loading rare earth element-based upconversion nanoparticles (UCNPs) into chiral ZIFs, upconverted CPL (UC-CPL) could be achieved with a high dissymmetry factor (
). Thus, various achiral luminophores were endowed with CPL upon coupling with chiral ZIFs, which significantly deepened and enlarged the research scope of the chiroptical materials in a solid state.
Transparent roofs and walls offer a compelling solution for harnessing natural light. However, traditional glass roofs and walls face challenges such as glare, privacy concerns, and overheating ...issues. In this study, we present a polymer-based micro-photonic multi-functional metamaterial. The metamaterial diffuses 73% of incident sunlight, creating a more comfortable and private indoor environment. The visible spectral transmittance of the metamaterial (95%) surpasses that of traditional glass (91%). Furthermore, the metamaterial is estimated to enhance photosynthesis efficiency by ~9% compared to glass roofs. With a high emissivity (~0.98) close to that of a mid-infrared black body, the metamaterial is estimated to have a cooling capacity of ~97 W/m
at ambient temperature. The metamaterial was about 6 °C cooler than the ambient temperature in humid Karlsruhe. The metamaterial exhibits superhydrophobic performance with a contact angle of 152°, significantly higher than that of glass (26°), thus potentially having excellent self-cleaning properties.
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