Chiral metal halide perovskites are promising for circularly polarized optoelectronic devices, yet achieving strong chiroptical responses across a broad spectral range on a large scale remains challenging. Here, we demonstrate the hierarchical self-assembly of CsPbBr3 nanoplatelets functionalized with enantiomeric phenylethylammonium (PEA) bromide ligands into twisted microbelts with controlled handedness (R/S), driven by solvent evaporation and accompanied by a phase transition toward a hybrid 2D/0D (R-/S-PEA)2PbBr4/Cs4PbBr6 structure. The resulting microbelts exhibit broadband circular dichroism in a spectral range from 200 to 750 nm and an absorption dissymmetry factor (gabs) of up to 2.3 & times; 10-3, increasing from the 10-5 range for the pristine chiral nanoplatelets and thus representing an enhancement of approximately 2 orders of magnitude. Our study establishes hierarchical self-assembly assisted by chiral ligands with the subsequent crystal phase transition as a powerful strategy for engineering large-scale chiral perovskite architectures with programmable chirality.

A major challenge in chiral carbon nanoparticles is to create materials whose chirality persists outside aqueous environments and remains functional under organic synthesis, interfacial engineering, and device fabrication conditions. We overcome this barrier by developing intrinsically chiral, organo-soluble carbon nanocolloids (CNCs) through solvent-free thermal condensation of enantiopure α-methylbenzylamine with formamidinium salts at 180 °C. Unlike conventional surface-functionalized chiral carbon dots, these CNCs form amorphous carbon-nitrogen-oxygen networks with covalently embedded chiral amidinium chromophores, as confirmed by experimental studies and molecular dynamics simulations. The resulting nanoparticles (5-10 nm in size) are easily dispersible in both polar and nonpolar solvents while maintaining their structural integrity, which is demonstrated by retention of nonvibrational photoluminescence bands in Cl-containing solvents. Chiral CNCs display both bright blue emission (quantum yield up to 40%) and distinct circular dichroism signals (|g| = 3.1-3.7 × 10-4) spanning 250-450 nm in spectral range. Using these CNCs, we demonstrate enantioselective sensing of chiral amines in toluene via dual modulation of photoluminescence and circular dichroism, and passivation of CsPbBr3 perovskite films, which simultaneously enhances their emission intensity and ambient stability. This study introduces a novel class of intrinsically chiral CNCs bridging molecular stereochemical precision with nanoscale colloidal stability for advanced chiral optoelectronics and sensing in organic media.

Impact of biotinylation strategy on the luminescent properties and quantum yield of carbon dots (CDs) is systematically investigated for four types of solvothermally synthesized CDs from citric acid and urea in dimethylformamide (CD-CU), citric acid in formamide (CD-CF), citric acid and ethylene diamine in formamide (CD-CEF), and glutathione in formamide (CD-GF) emitting in the 470–690 nm range. We compare direct carbodiimide coupling (EDC/NHS) with a two-step method employing presynthesized biotin NHS ester, followed by conjugation to CDs in aqueous media. Direct coupling (Method 1) leads to substantial quenching of surface-related emissive centers and formation of urea by-products, which strongly reduce photoluminescence quantum yield (PLQY), while careful purification partially restores the initial optical responses. In contrast, the NHS-ester strategy (Method 2) efficiently attaches biotin with minimal perturbation of the CD optical responses, preserving or even enhancing PLQY. In particular, glutathione/formamide-derived CDs (CD-GF) demonstrate the highest robustness: their deep-red emission is retained, and PLQY increases from 10.6

Near‐infrared (NIR) light sources based on colloidal two‐dimensional (2D) semiconductor heterostructures hold significant promise for biomedical imaging and optical communications, yet their practical deployment is constrained by surface trap‐mediated nonradiative decay and poor solid‐state stability. Herein, we report a solution‐processable interfacial passivation strategy for PbSe/PbS core/shell and core/wings nanoplatelets using a mixed‐halide CsPb(Br/I) 3 perovskite matrix. Comprehensive structural and spectroscopic analyses demonstrate that the perovskite overlayer effectively suppresses surface defects, yielding a 2.3–2.7× enhancement in relative photoluminescence intensity and extending emission lifetimes to 3.8 ns while preserving the intrinsic NIR/short‐wave infrared (SWIR) emission profiles. When integrated into solution‐processed devices, the passivated films enable down‐conversion light‐emitting diodes (LEDs) with radiance of up to 0.026 W/sr/m 2 under 450 nm excitation, as well as charge‐injection LEDs exhibiting a low turn‐on voltage of ~4.1 V and electroluminescence at 1310 and 1610 nm. This work establishes a robust surface‐engineering framework that bridges colloidal 2D lead chalcogenide heterostructures with practical solid‐state optoelectronics, paving the way for novel NIR/SWIR emitters.

Lead-free halide double perovskite nanocrystals have emerged as one of the most promising alternatives to lead halide perovskite nanocrystals due to their non-toxicity, high stability, and outstanding optoelectronic properties. However, conventional synthesis methods often result in impurities due to increased constituent elements. In this study, an efficient water-oil biphasic interface-driven approach is introduced for synthesizing lead-free double perovskite nanocrystals, enabling controlled structural transformations from 0D to 2D and 3D structures. Starting from 0D Cs3BiBr6, a gradual cation exchange is achieved, forming 3D Cs2AgBiBr6. Real-time monitoring reveals the slow insertion of Ag+ ions as the key to the structural transformation. The resulting Cs2AgBiBr6 nanocrystals exhibit exceptional stability, maintaining their integrity for over 120 days under ambient conditions without significant degradation, showing no considerable material decomposition. Additionally, this method allows for the successful synthesis of 2D layered double perovskite Cs4ZnBi2Br12, which has not previously been reported in experimental studies. This biphasic synthesis strategy provides a universal and reliable method for producing high-quality double perovskite nanocrystals while offering valuable insights into their structural dynamics and properties.

Bioimaging probes based on carbon dots (CDs) can become a useful replacement for existing commercial probes, benefiting clinical diagnostics. While the development of dual-mode CD-based probes for magnetic resonance imaging (MRI), which provides the ability for photoluminescence (PL) detection at the same time, is ongoing, several challenges have to be addressed. First, most of the CD-based probes still emit at shorter wavelengths (blue/green spectral range), which is harmful to biological objects or have very low PL intensity in the biological window of tissue transparency (red/near-infrared spectral range). Second, the relaxation characteristics of the proposed CD-based probes are still similar or only slightly larger than those of commercial contrast agents. Herein, we introduce a dual-mode probe allowing for simultaneous PL detection and MRI analysis, based on CDs doped with gadolinium ions (Gd3+) with a PL peak in the red (640 nm), a PL quantum yield up to 24%, and high longitudinal and transverse relaxivities reaching 25.76 and 40.57 L mmol-1 s-1, respectively. Moreover, Gd-doped CDs show good biocompatibility, which was studied on H9c2 and 4T1 cell lines with a cell viability above 70%. The developed Gd-doped red-emissive CDs can be utilized as efficient and nontoxic dual-mode probes for PL and MRI measurements carried out simultaneously.

Circularly polarized luminescence (CPL) of chiral perovskite nanocrystals is crucial for applications such as spin-polarized light-emitting diodes and chiral photodetectors. However, the reported luminescence dissymmetry factors are often too low for practical applications; it is also important for CPL wavelengths to cover the red emission range for display applications. Herein, we realized helical perovskite nanowires self-assembled from red-emitting CsPbI3 quantum dots (QDs) with a strong CPL signal around 640 nm, which was enabled by chiral ligand R-/S-binaphthyl phosphoric acid. The formation of CsPbI3 nanowires from perovskite QDs occurred by oriented attachment; QDs remaining in solution attached at the surface of the nanowires, forming helical structures. The films produced from these chiral nanowires demonstrate high dissymmetry factors of 1.1 × 10-2 and 2.3 × 10-2 for absorption and luminescence, respectively, surpassing many previously reported chiral nanomaterials. We employed multilayer nanowire films as chiral filters, generating left- and right-handed CPL.

The development of high-performance perovskite light-emitting diodes (PeLEDs) typically requires thermal annealing to optimize the crystallization and film quality. However, this energy-intensive process limits the scalability and environmental sustainability of perovskite-based devices. Here, we demonstrate a novel approach to fabricating high-quality perovskite emitting layers without the need for annealing, utilizing carbon dots (CDs) as an interface layer. The CDs, functionalized with abundant potassium ions, carboxylate, and amino groups, serve as nucleation centers and enhance precursor interactions. This facilitates room-temperature perovskite crystallization by lowering the formation energy, guiding uniform crystal growth, and improving the overall quality of the perovskite layer. Consequently, annealing-free PeLEDs demonstrate superior performance with a maximum external quantum efficiency of 20.5%, and large-area PeLEDs (225 mm2) exhibit a high efficiency of 16.6%. This strategy not only eliminates the need for thermal processing but also enhances the electroluminescent performance, offering a scalable, low-cost, and energy-efficient pathway for fabricating high-performance perovskite-based optoelectronic devices.

Carbon dots (CDs) are fluorescent carbon nanomaterials that are considered for applications in optoelectronics, sensorics, and biofields due to their low‐cost and robust synthesis, and versatile optical properties. Herein, it is demonstrated how chemical functionalization of hydrophilic or amphiphilic CDs with polyethylene glycol influences their energy level structure and hence the emission properties. Functionalization of CDs with polyethylene glycol results in an increase in emission quantum yield: from 30% to 75% for hydrophilic CDs and from 20% to 25% for amphiphilic CDs. The estimated absolute values of energy levels, including the highest occupied molecular orbital and the lowest unoccupied molecular orbital energies, are dependent on chemical composition and size of CDs. Moreover, polyethylene glycol‐functionalized CD can form good quality films based on their composite with polyvinylcarbazole (PVK), that together with intense emission is crucial for light‐emitting diode (LED) fabrication. By studying spectral properties of fabricated CD‐LEDs, it is shown that their electroluminescence (EL) originates from mixed energy levels of CD and PVK in the composite, resulting in the shifting of the EL maximum from blue to green during several seconds of LED operation. The optimized CD‐LEDs show brightness up to 2600 cd m−2.

Chirality‐induced spin selectivity (CISS) enables spin‐polarized charge transport through chiral media without magnetic fields. While extensively studied in organic and biomolecular systems, CISS in semiconductors remains limited, lacking standardized methodologies and mechanistic understanding. II‐VI and III‐V semiconductor nanocrystals (NCs), with tunable band gaps, high optical quality, strong spin‐orbit coupling (SOC) and diverse morphologies, provide an ideal platform for exploring spin‐dependent phenomena. This review highlights fundamental concepts of chirality and its manifestation in nanostructures, distinguishing ligand‐induced and intrinsic chirality in NCs. This work critically integrates recent advances on the microscopic link between chirality and spin selectivity, emphasizing mechanisms such as exciton‐ligand hybridization, and surface/bulk inversion asymmetries that generate Rashba/Dresselhaus effects, leading to interfacial spin‐filtering. This work describes structural control and chiroptical properties of chiral II‐VI/III‐V NCs, discussing factors like morphology, surface defects, and ligand chemistry, while outlining trade‐offs among SOC, optical quality, and device integration. Mechanistic models, including exciton‐ligand hybridization and photonic coupling, explain trends in circular dichroism. Strategies for tuning spin injection, transport, and relaxation are outlined, emphasizing SOC, structural anisotropy, and compositional engineering. This work assesses challenges in integrating chiral NCs into practical devices – including stability, scalability, environmental safety – and highlight opportunities in spin‐LEDs, quantum computation, biosensing, and memory devices.

Despite considerable advancements in the power conversion efficiency (PCE) of lead halide perovskite solar cells (PSCs), their operational durability remains a pivotal challenge for their widespread commercialization. One of the primary sources of instability of PSCs is the halide anion migration in the perovskite layer, causing a lack of stability of the perovskite crystal structure, particularly when subjected to increased temperature and moisture, which results in reduction in the PCE. Undesirable ion migration can be eliminated through advancements in PSC architecture, such as proper design of electron and hole transport layers and incorporation of nanoparticle additives such as carbon dots (CDs) into the perovskite layer. This study has shown that negatively charged amphiphilic CDs with many aliphatic, carbonyl, and hydroxyl groups at the surface are effective in suppressing the iodide migration process and thus improve the performance and stability of PSCs based on FACsPbI3 (FA stays for the formamidinium cation). Introduction of these CD additives affects the crystallization process of FACsPbI3 perovskite films, causing an increase of the perovskite grain size by 81% and at the same time a diminished appearance of the undesired PbI2 phase as compared to the reference sample without CDs. Furthermore, incorporation of CDs into perovskite films enables us to adjust their energy level structure, facilitating charge carrier extraction in PSCs. As a result, PSCs based on the FACsPbI3 perovskite films with amphiphilic poly(ethylene glycol)-covered CDs demonstrate an increase in the maximum short-circuit current and suppressed hysteresis between forward and reverse scans. The latter effect is attributed to the passivation of defects, which results in the reduction of the ion migration pathways and the amount of I- anions at the interface between the electron transport layer and the perovskite active layer. These improvements result in a maximum PCE of such PSCs of 15%, which is 29% higher as compared to the maximum value of PCE for the reference device without any CDs.

A post-synthetic modification strategy is presented to induce a chirality in red-emissive carbon dots (CDs) by covalent bonding with chiral isocyanates. The resulting chiral CDs exhibit circular dichroism signals in the 300–500 nm range with a dissymmetry factor of 8 × 10− 5 at 345 nm, distinct from their chiral precursors. These chiral CDs maintain photoluminescence in the red spectral range (615–640 nm) and reasonably high quantum yield of 12–13

The availability of nanomaterials with optical transitions in the near-infrared spectral range is of great importance for the development of solar cells and photodetectors, as well as for (bio)sensing and biolabelling. One attractive class of such materials comprises colloidal nanocrystals of ternary semiconductor materials, namely I-III-VI2 compounds which eventually can be doped with Zn(II) to become quaternary (I-II-III-VI) compounds. Recently, anisotropic shapes of these nanocrystals have been reported, with some specific areas of potential applications related to anisotropy in their optical responses, such as chiroptical responses in absorption and emission. In this review, we summarize the state-of-the-art approaches for the synthesis of ternary and quaternary (Zn-doped) Cu- and Ag-based chalcogenide nanocrystals with a special focus on their anisotropic shapes (such as nanorods and nanowires). We consider their energy level structure and spectral characteristics, including chiroptical properties, and provide perspectives in a view of their potential applications.

Circularly polarized luminescence is an attractive characteristic of chiral perovskite nanocrystals, as it opens possibilities for applications such as spin-polarized light-emitting diodes and chiral light-selective photodetectors. While previous research has mainly focused on green- and red-emitting chiral perovskite nanocrystals, the exploration of blue-emitting counterparts with efficient circularly polarized luminescence activity is still in its early stages. Here, we synthesize nanocubes, nanoribbons, and nanowires of CsPbBr3 perovskites, which exhibited strong blue emission thanks to quantum confinement in at least two dimensions. Their chiral induction is achieved by attaching chiral molecules (R/S-methylbenzylammonium bromide) to the surface of nanocrystals, resulting in circular dichroism and circularly polarized luminescence. Upon attachment of chiral ligands, the average absorption dissymmetry factor, |gabs|, reached 9 x 10(-5) for nanocubes, 1.5 x 10(-4) for nanoribbons, and 2.9 x 10(-4) for nanowires, thus clearly revealing shape-dependence. Moreover, we achieved blue circular polarized luminescence for all three kinds of samples, with the average luminescence dissymmetry factor, |glum|, of 1.4 x 10(-4), 4 x 10(-4), and 5.2 x 10(-4) for nanocubes, nanoribbons, and nanowires, respectively.

Subject of study. This study is focused on luminescent carbon dots derived from o-phenylenediamine and gadolinium chloride or nitrate hexahydrate. Aim of study. The study aims to fabricate long-wavelength photoluminescent gadolinium-doped carbon dots that could function as contrast agents for magnetic resonance imaging. Additionally, the study investigates the impact of the precursor type used on the chemical composition and optical transitions of the resulting nanoparticles. Method. Carbon dots were synthesized using a one-step solvothermal method, and their composition and optical properties were analyzed using spectroscopy methods. Magnetic resonance imaging was conducted using a clinical magnetic resonance imaging scanner with a field strength of 1.5 T. Main results. In this study, two types of carbon dots were synthesized from o-phenylenediamine and gadolinium chloride or nitrate hexahydrate using the solvothermal method. Metal doping, at a concentration sufficient for further investigations, is achieved only when gadolinium chloride is used. Additionally, the presence of gadolinium chloride during the synthesis leads to the formation of luminescent centers within the carbon dots with emission at 600-720 nm and a photoluminescence quantum yield of 6.3%. In contrast, gadolinium nitrate increases the nitrogen content within the o-phenylenediamine-based carbon dots while inhibiting metal doping. The luminescent band with an emission maximum at 550 nm and a photoluminescence quantum yield of 7.4% originates from the o-phenylenediamine derivatives formed within such carbon dots. The study results also show that the gadolinium-doped carbon dots alter the relaxation times during magnetic resonance scanning, and the calculated relaxivity (r1 and r 2 ) values are 6.4 and 38.6 L mmol-1 s-1, respectively. Thus, the synthesized carbon dots function as positive contrast agents during magnetic resonance scanning. Practical significance. Carbon dots with long-wavelength emission are promising nanoprobes for luminescence imaging. With gadolinium doping, these nanoparticles can also be used as contrast agents during magnetic resonance imaging. Consequently, carbon dots based on o-phenylenediamine and gadolinium chloride hexahydrate can be further utilized as dual-mode nanoprobes for bioimaging. (c) 2024 Optica Publishing Group

Active optical materials with intrinsic chirality, in particular, circularly polarized luminescence (CPL), are highly demanded for utilization in data processing, bioimaging, and photocatalytic asymmetric synthesis. Crystal structure engineering, chiral assembly, and chirality imprinting by chiral ligands were proposed for fabrication of CPL-active materials. The former approach is applicable to colloidal perovskite nanocrystals (PNCs), which attract significant attention due to their outstanding optical properties and high tunability. However, the issues of chiral perovskite NC stability, control of the bandgap, and achieving high photoluminescence quantum yield and emission dissymmetry factor simultaneously remain unresolved. To overcome these obstacles, we developed mixed-halide chiral perovskite NCs by simultaneous anion and ligand exchanges, which provide the passivation of surface defects and induce a chiral response. As a result, the chiral PNCs exhibit CPL with dissymmetry factors up to 3.4 x 10- 2 and a photoluminescence quantum yield up to 98 %, making the proposed approach promising for chirality imprinting.

In this work, composite materials were formed based on various matrices (polymer and porous cellulose matrix) and carbon dots (CDs) with intense room temperature phosphorescence (RTP). The effect of postsynthesis chemical treatment with citric acid or urea on the optical properties of composites was studied: the increase in carboxy and carbonyl groups lead to an increase of RTP signal which can be seen with the naked eye over several seconds. Fabricated composites demonstrate good stability and reversibility of RTP signal by mild heating. Based on developed CDs, luminescent inks were used for simple demonstration of the data encryption on a paper.

In this work, copper-doped carbon nanoparticles with emission in a wide spectral range and the ability to change the relaxation times of water protons during magnetic resonance imaging were fabricated. A high relaxivity value r1 = 0.92 mM–1 s–1 was achieved, which is the highest value of r1 for copper nanoparticles, to our knowledge. The suggested carbon nanoparticles are promising two-modal nanoprobes for bioimaging.

Subject of study. The spectral features of nanocrystals with ternary compositions I-V-VI2 and I-III-VI2 doped with the rare earth metal ytterbium are investigated and described. Purpose of the study. The aim of this work is to develop a novel synthesis method for these nanocrystals to further examine their optical and morphological properties. Method. The average sizes of AgInS2:Yb and AgBiS2:Yb nanocrystals are analyzed using atomic force microscopy and dynamic light scattering, and the results are compared. Spectrophotometry and spectrofluorimetry are employed to record the absorption and photoluminescence spectra, respectively. Additionally, the photoluminescence decay kinetics are recorded using a laser scanning luminescence microscope for a deeper exploration of the electronic structure of the synthesized materials. Main results. Morphological analysis reveals that single-stage synthesis produced nanocrystals based on the AgInS2 matrix are smaller than the reference sample, while two-stage synthesis results in average nanocrystal sizes 1.5 times larger than the reference sample. The absorption spectra of the AgInS2:Yb and AgBiS2:Yb samples, as well as their reference samples, correspond to typical absorption spectra of semiconductor nanocrystals of ternary compounds. The absorption spectrum of AgBiS2:Yb nanocrystals, unlike AgInS2:Yb, spans a broad range from 300 nm to 1300 nm. In the photoluminescence spectra of AgInS2 and AgInS2:Yb nanocrystals, no significant shift of the band maximum is observed, and photoluminescence typical of Yb ions is absent. It is found that the weighted average photoluminescence lifetime in AgInS2:Yb nanocrystals can be modulated by ytterbium doping. Photoluminescence in AgBiS2 and AgBiS2:Yb samples is not detected in the red and near-infrared regions. Practical significance. These materials may be used in the fabrication of absorber layers for solar cells, as well as sensitizers for photodynamic and photothermal therapy. Further studies of isotropic samples of these nanocrystals could not only expand their potential applications but also enhance the physical properties of nanoparticles in the long term. (c) 2024 Optica Publishing Group