Absolute Photoluminescence Quantum Yield Research Articles

Polymerizable Surfactant Ligand for Stabilization and Film Formation of CsPbBr3 Nanocrystals.

Surfactant ligands are important in the synthesis of inorganic perovskite nanocrystals (NCs), not only for stabilizing NCs but also for surface defect passivation. A new polymerizable surfactant ligand with a multidentate l-cysteine head, a long oleoyl tail, and a polymerizable styrenyl group (NOSVC) is designed for the post-synthesis treatment and stabilization of colloidal CsPbBr3 NCs in this work. 1H nuclear magnetic resonance and X-ray photoelectron spectroscopy analysis show that the l-cysteine head has strong interactions with the NCs. The absolute photoluminescence quantum yields of the colloidal NCs are increased from 45.1% of the pristine NCs stabilized with oleic acid/oleyl amine to 91.8% after NOSVC treatment. NOSVC-stabilized CsPbBr3 colloidal NCs show enhanced stabilities when exposed in polar solvents. The NOSVC-stabilized CsPbBr3 NCs in a solid film state allow for a photopolymerization to be carried out with the assistance of a photoinitiator. The polymerized films of NOSVC-treated NCs exhibit significantly enhanced stability against thermal radiation, ultraviolet irradiation, and humidity. We also fabricated self-healing polymer films incorporating NOSVC-treated CsPbBr3 NCs as a green filter for a white light-emitting diode device. The green light-emitting films are very stable in humid environments, revealing the great application potential of NOSVC-treated CsPbBr3 NCs in flexible display and lighting devices.

Highly efficient solid-state luminescence of carbonized polymer dots without matrix

Development of high-performance solid state luminescent carbon-based nanomaterials remains challenging. Here, strong blue-green fluorescent carbonized polymer dots (CPDs) from o-aminobenzenethiol and thiosalicylic acid (oABT-TSA-CPDs) with an absolute photoluminescence quantum yield (PLQY) of 76% in solid state without matrix were synthesized. Through adjusting the reaction temperature and time, the PL centers were proved to be carbon core state and surface state associated to carbonyl group which was the source of strong fluorescence emission in solid state. The mechanism of the unique phenomenon of enhanced emission from ethanol solution (PLQY = 7%) to powder (PLQY = 76%) was investigated by analyzing the chemical properties and structures of oABT-TSA-CPDs at different temperatures and oABT-TSA-CPDs/PVC composites, and was confirmed as fixation of PL centers.

Highly Emissive Luminogens in Both Solution and Aggregate States

Highly Emissive Luminogens in Both Solution and Aggregate States

High‐Quality Cs3Cu2I5 Single‐Crystal is a Fast‐Decaying Scintillator

AbstractCopper(I) halide perovskite Cs3Cu2I5 has recently attracted tremendous interest and has been considered an exceptionally promising scintillator due to its high quantum yield. However, its slow scintillation decay time, previously considered an intrinsic property, is a significant drawback preventing its practical application and commercialization. But in this work, it is found that the high‐quality Cs3Cu2I5 single‐crystal grown by the designed aqueous solution method surprisingly exhibits a fast scintillation decay time of 39 ns (82%), quite different from previous reports. This subversive change may be due to the high crystal quality with denser 0D structure and low trap density (6.41 × 108 cm–3), changing the excited‐state structural deformation and accelerating the recombination of electrons and holes while directly reducing the prolongation of decay time caused by inherent defects. Moreover, the single‐crystal with a rocking curve FWHM value of only 50.4˝ has a high optical transmittance (85%), a very high absolute photoluminescence quantum yield (PLQY, 97.76%), superior environmental stability, and excellent light‐yield and energy resolution under different γ‐ray sources (241Am, 60Co, 22Na, 137Cs, 152Eu). These extraordinary properties pave the way for the subsequent development of practical applications.

Transparent Nanocomposites Comprising Ligand-Exchanged CuInS2/ZnS Quantum Dots and UV-Cured Resin for Wavelength Converters

Quantum dots (QDs) dispersed in UV-curable resin are used for patterning in photolithography and inkjet printing. However, low affinity between the main component of UV-curable resins known as celloxide, an alicyclic diepoxy compound, and QD surface ligands with alkyl chains causes significant aggregation of QDs. In this study, the dispersibility of core/shell CuInS2/ZnS QDs with adsorbed 1-dodecanethiol and oleic acid in celloxide was improved using the ligand exchange method to prepare transparent fluorescent nanocomposites. Cyclohexyl 3-mercaptopropionate (MPACH) and 3-mercaptopropionic acid (MPA) were successfully adsorbed onto the QDs. MPACH-modified QDs (QD-MPACH) were well dispersed in the UV-curable resin, whereas MPA-modified QDs (QD-MPA) exhibited significant aggregation. Nanocomposite plates containing dispersed QDs were prepared by UV irradiation. The QD-MPACH nanocomposite plate was transparent, while the QD-MPA nanocomposite plate was turbid. The homogeneous dispersion of QD-MPACH was attributed to the similarity in the molecular structure between MPACH and celloxide. The photoluminescence (PL) peak of the QD-MPA nanocomposite occurred at a longer wavelength than that of the QD-MPACH nanocomposite. Furthermore, compared with the absolute photoluminescence quantum yield (PLQY) of the as-prepared QDs in toluene (55%), that of the QD-MPA nanocomposite was smaller (46%), and that of the QD-MPACH nanocomposite was higher (61%). An enhanced self-absorption effect was observed for the QD-MPA nanocomposite because of significant light scattering by the aggregates and concentration quenching, resulting in the PL redshift and decreased PLQY. Moreover, the PL intensity of the QD-MPACH nanocomposite was maintained at 98% of the initial value after continuous excitation-light irradiation for 5 h. The high PLQY and photostability of the QD-MPACH nanocomposite are beneficial in practical applications.

AgAuSe quantum dots with absolute photoluminescence quantum yield of 87.2%: The effect of capping ligand chain length

AgAuSe quantum dots with absolute photoluminescence quantum yield of 87.2%: The effect of capping ligand chain length

Near-infrared piezochromism of AIE-active luminophore in hybridized local and charge-transfer excited state—the effect of shortened donor-acceptor distance

A close-bonded D-A-D′ luminophore BOTPA was designed via direct coupling of secondary arylamine derivatives (D, D′) with benzothiadiazole cyanostilbene group (A). Both near-infrared (NIR) aggregation-induced emission (AIE) and hybridized local and charge-transfer (HLCT) effects, which endow it with highly efficient NIR piezochromic performance, are observed owing to its especially short D-A distance and twisted conformation. The luminophore shows bright fluorescence at 740 nm with an absolute photoluminescence quantum yield (PLQY) as large as 13.2%. Remarkable piezochromism with high sensitivity (11.0 nm•Gpa−1) completely in the NIR region (700–840 nm) could be observed from BOTPA crystals, which is rarely found in piezochromic materials (PCMs). The effects of the shortened D-A distance towards the highly efficient NIR piezochromism are confirmed via single-crystal analysis, in-situ FTIR and theoretical calculations. This work provides a new strategy for the development of high-efficiency NIR PCMs which possess strong penetrating capacity.

Simple Double Hetero[5]helicenes Realize Highly Efficient and Narrowband Circularly Polarized Organic Light-Emitting Diodes

Simple Double Hetero[5]helicenes Realize Highly Efficient and Narrowband Circularly Polarized Organic Light-Emitting Diodes

Luminescent Thin Films Enabled by CsPbX3 (X=Cl, Br, I) Precursor Solution.

Inorganic cesium lead halide perovskite nanocrystals are candidates for lighting and display materials due to their outstanding optoelectronic properties. However, the dissolution issue of perovskite nanocrystals in polar solvents remains a challenge for practical applications. Herein, we present a newly designed one-step spin-coating strategy to prepare a novel multicolor-tunable CsPbX3 (X=Cl, Br, I) nanocrystal film, where the CsPbX3 precursor solution was formed by dissolving PbO, Cs2 CO3 , and CH3 NH3 X into the ionic liquid n-butylammonium butyrate. The as-designed CsPbX3 nanocrystal films show high color purity with a narrow emission width. Also, the blue CsPb(Cl/Br)3 film demonstrates an absolute photoluminescence quantum yields (PLQY) of 15.6 %, which is higher than 11.7 % of green CsPbBr3 and 8.3 % of red CsPb(Br/I)3 film. This study develops an effective approach to preparing CsPbX3 nanocrystal thin films, opening a new avenue to design perovskite nanocrystals-based devices for lighting and display applications.

Low-temperature synthesis of stable blue Cesium lead bromide perovskite nanoplates with high quantum efficiency for display applications

Despite heavy research, the efficiencies of blue perovskite light-emitting diodes (LEDs) lag behind those of their green and red cousins. One of the most critical problems is the lack of technology to obtain both high blue emission and spectral stability of perovskite in thin films. Herein, we employ low-temperature synthesis of CsPbBr3 nanoplates (NPLs) by anti-solvent assisted crystallization method using green ethylacetate anti-solvent, which show high absolute photoluminescence quantum yield (PLQY = 90.2%), blue emission at 464 nm with a narrow emission line width (15 nm), small Stokes shift (5 nm) and the average PL decay lifetime (6.91 ns). Significantly, there is no obvious QY loss at different storage conditions. Furthermore, the PL can be tuned from blue to green (457–513 nm) by controlling the amount of precursor injected into anti-solvent. For the first time, we utilize all-bromide-based inorganic perovskites to fabricate ultraviolet-pumped white LEDs (UV-WLEDs) and optimize the chromaticity coordinate of WLEDs, whose CIE color temperature (CCT) is 6083 K. Finally, highly efficient blue LED device using CsPbBr3 nanoplates (464 nm) with high external quantum efficiency (EQE) of 2.03% was fabricated and spectral stability of CsPbBr3 nanoplates under constant current density was demonstrated. This work will be expected to facilitate the development of the blue light source for WLEDs and displays.

Feasibility of Emission-Enhanced CsPbCl3 Quantum Dots Co-Doped with Mn2+ and Er3+ as Luminescent Downshifting Layers in Crystalline Silicon Solar Modules

In order to enhance the photoelectric conversion efficiencies of crystalline silicon (c-Si) solar cells, CsPbCl3 quantum dots (QDs) codoped with Mn2+ and Er3+ (CsPbCl3:Mn2+, Er3+ QDs) were mixed with ethylene–(vinyl acetate) (EVA) to form a film which was used as a luminescent down-shifting (LDS) layer. The LDS layer effectively improved the low utilization of near-ultraviolet light of c-Si solar cells. These CsPbCl3:Mn2+,Er3+ QDs were synthesized via a conventional high-temperature injection method. Mn2+ is the luminescence center, and the incorporation of Er3+ greatly enhances the luminescence intensity of Mn2+. The absolute photoluminescence quantum yield of the QDs dispersed in toluene reached 79.5% when the QDs were synthesized under the optimum conditions, that is, an injection temperature of 180 °C and Pb:Mn:Er preparation molar ratios of 6:4:4. The EVA film embedded with QDs at the optimum concentration (0.9 wt %) was used as an LDS layer for c-Si solar module. The short-circuit current (ISC) and the photoelectric conversion efficiency (η) were increased by 3.42% and 4.02%, respectively, owing to the LDS layer. Moreover, a luminescent solar concentrator (LSC) which was another application of luminescent materials was also demonstrated. For LSC, the relative changes in ISC and η by using the QDs-dispersed EVA film were +14.9% and +18.0%, respectively. These results indicate a feasible application of luminescent downshifting films in solar modules.

Enhancing Intersystem Crossing by Intermolecular Dimer-Stacking of Cyanine as Photosensitizer for Cancer Therapy

Enhancing Intersystem Crossing by Intermolecular Dimer-Stacking of Cyanine as Photosensitizer for Cancer Therapy

Orange emissive N-doped carbon dots and their application in detection of water in organic solvents and the polyurethane composites

In this work, efficient orange emissive N-doped carbon dots (N-CDs) were synthesized through a facile one-step solvothermal route using 1,4-phenylene diisocyanate as the only raw precursor. The as-prepared N-CDs exhibited strict excitation independent luminescence with a maximum emission peak at 581 nm. The absolute photoluminescence quantum yield was up to 38%. A reasonable formation process of N-CDs was explored in detail. Interestingly, the N-CDs was sensitive to water and thus, could be exploited as an excellent fluorescent probe directly for quantitative detection of water in organic solvents. Moreover, various orange-emitting N-CDs/polymer composites were achieved by simply incorporating the N-CDs into different polymer matrices. The N-CDs could be better uniformly dispersed in polyurethane (PU) matrix through the in situ polymerization technique, and the emission intensity of N-CDs/PU composite films could be linearly modulated by changing the N-CDs concentration. These investigations broaden promising application potentials of CDs in sensor and optoelectronic devices.

Si-assisted N, P Co-doped room temperature phosphorescent carbonized polymer Dots: Information Encryption, graphic Anti-counterfeiting and biological imaging

Room temperature phosphorescence (RTP) materials have been widely noticed due to their superior optical properties in the past decade. Herein, we report the Si-assisted N, P co-doped RTP carbonized polymer dots (CPDs), prepared by one-step microwave assisted heating of 3-(2-Aminoethylamino)propyldimethoxymethylsilane and phosphoric acid aqueous solution. The obtained CPDs exhibit bright RTP with an absolute photoluminescence quantum yield 34.17%, absolute phosphorescence quantum yield 11.42% and long lifetime of 1.42 s, which lasts for about 16 s to the naked eyes. We apply the obtained CPDs into information encryption and Polyethyleneterephthalate (PET) film graphic anti-counterfeiting with facile way. Additionally, we make more efforts to realize aqueous RTP CPDs composite. The obtained aqueous CPDs composite exhibits bright aqueous RTP with absolute photoluminescence quantum yield (QY) of 12.61%, absolute phosphorescence quantum yield (QY) of 5.08% and RTP lifetime of 1.46 s, which lasts for about 10 s to the naked eyes. The RTP CPDs composite is nontoxic and biocompatible. These brilliant characteristics allow CPDs composite to be applicable in biological imaging. Thisstudy affords a new RTP material which can be easily prepared and used for information encryption, graphic anti-counterfeiting and biological imaging

Monocyclometalated (C N) Gold(III) Metallacycles: Tunable Emission and Singlet Oxygen (1 O2 ) Generation Properties.

The synthesis, characterization and photoluminescent properties of four cyclometalated (C N)-type gold(III) complexes bearing a bidentate diacetylide ligand, tolan-2,2'-diacetylide (tda), are reported. The complexes exhibit highly tunable excited state properties and show photoluminescence (PL) across the entire visible spectrum from sky-blue (λPL =493 nm) to red (λPL =675 nm) with absolute PL quantum yields (PLQY) of up to 75 % in solution, the highest PLQY found for any monocyclometalated Au(III) complex in solution. As a consequence of the use of the strongly rigidifying diacetylide bidentate ligand, a significant increase in the excited state lifetimes (τ0 =16-258 μs) was found in solution and in thin films. The complexes showed remarkable singlet oxygen generation in aerated solution with absolute singlet oxygen quantum yield (ϕ1Δ ) values reaching up to 7.5×10-5 and singlet oxygen lifetimes (τ0 1Δ ) in the range of 66-95 μs. Furthermore, the radiative and non-radiative rates of singlet oxygen were determined using the ϕ1Δ and τ0 1Δ values and correlations are drawn between the formation of singlet oxygen and its interaction with cyclometalated (C N) gold(III) complexes.

High Mobility Organic Lasing Semiconductor with Crystallization‐Enhanced Emission for Light‐Emitting Transistors

AbstractThe development of high mobility organic laser semiconductors with strong emission is of great scientific and technical importance, but challenging. Herein, we present a high mobility organic laser semiconductor, 2,7‐diphenyl‐9H‐fluorene (LD‐1) showing unique crystallization‐enhanced emission guided by elaborately modulating its crystal growth process. The obtained one‐dimensional nanowires of LD‐1 show outstanding integrated properties including: high absolute photoluminescence quantum yield (PLQY) approaching 80 %, high charge carrier mobility of 0.08 cm2 V−1 s−1, Fabry‐Perot lasing characters with a low threshold of 86 μJ cm−2 and a high‐quality factor of ≈2400. Furthermore, electrically induced emission was obtained from an individual LD‐1 crystal nanowire‐based light‐emitting transistor due to the recombination of holes and electrons simultaneously injected into the nanowire, which provides a good platform for the study of electrically pumped organic lasers and other related ultrasmall integrated electrical‐driven photonic devices.

High Mobility Organic Lasing Semiconductor with Crystallization-Enhanced Emission for Light-Emitting Transistors.

The development of high mobility organic laser semiconductors with strong emission is of great scientific and technical importance, but challenging. Herein, we present a high mobility organic laser semiconductor, 2,7-diphenyl-9H-fluorene (LD-1) showing unique crystallization-enhanced emission guided by elaborately modulating its crystal growth process. The obtained one-dimensional nanowires of LD-1 show outstanding integrated properties including: high absolute photoluminescence quantum yield (PLQY) approaching 80 %, high charge carrier mobility of 0.08 cm2 V-1 s-1 , Fabry-Perot lasing characters with a low threshold of 86 μJ cm-2 and a high-quality factor of ≈2400. Furthermore, electrically induced emission was obtained from an individual LD-1 crystal nanowire-based light-emitting transistor due to the recombination of holes and electrons simultaneously injected into the nanowire, which provides a good platform for the study of electrically pumped organic lasers and other related ultrasmall integrated electrical-driven photonic devices.

Breaking through the Size Control Dilemma of Silver Chalcogenide Quantum Dots via Trialkylphosphine-Induced Ripening: Leading to Ag2Te Emitting from 950 to 2100 nm.

Ag2Te is one of the most promising semiconductors with a narrow band gap and low toxicity; however, it remains a challenge to tune the emission of Ag2Te quantum dots (QDs) precisely and continuously in a wide range. Herein, Ag2Te QDs emitting from 950 to 2100 nm have been synthesized via trialkylphosphine-controlled growth. Trialkylphosphine has been found to induce the dissolution of small-sized Ag2Te QDs due to its stronger ability to coordinate to the Ag ion than that of 1-octanethiol, predicated by the density functional theory. By controlling this dissolution effect, the monomer supply kinetics can be regulated, achieving precise size control of Ag2Te QDs. This synthetic strategy results in state-of-the-art silver-based QDs with emission tunability. Only by taking advantage of such an ultrawide emission has the sizing curve of Ag2Te been obtained. Moreover, the absolute photoluminescence quantum yield of Ag2Te QDs can reach 12.0% due to their well-passivated Ag-enriched surface with a density of 5.0 ligands/nm2, facilitating noninvasive in vivo fluorescence imaging. The high brightness in the long-wavelength near-infrared (NIR) region makes the cerebral vasculature and the tiny vessel with a width of only 60 μm clearly discriminable. This work reveals a nonclassical growth mechanism of Ag2Te QDs, providing new insight into precisely controlling the size and corresponding photoluminescence properties of semiconductor nanocrystals. The ultrasmall, low-toxicity, emission-tunable, and bright NIR-II Ag2Te QDs synthesized in this work offer a tremendous promise for multicolor and deep-tissue in vivo fluorescence imaging.

Biomimetic Recognition-Based Bioorthogonal Host–Guest Pairs for Cell Targeting and Tissue Imaging in Living Animals

Biomimetic Recognition-Based Bioorthogonal Host–Guest Pairs for Cell Targeting and Tissue Imaging in Living Animals

Carbon dots embedded nanofiber films: Large-scale fabrication and enhanced mechanical properties

Valuable application prospects and large-scale production technologies are powerful driving forces for the development of materials science. Carbon dots (CDs) are a kind of promising carbon-based fluorescent nanomaterials, which possess wide application prospects based and even beyond the fluorescence properties. Herein, we report the fast and high-yield synthesis of CDs and the large-scale preparation of fluorescent nanofiber films with enhanced mechanical properties. CDs were prepared from magnetic hyperthermia treatment of citric acid and carbamide, with the output of 25.37 g in a single batch. The as-prepared CDs exhibit a high absolute photoluminescence (PL) quantum yield (QY) of 67% and wonderful dispersibility in polar solvents. Then, solution blow spinning of CDs and polymer matrixes of alcohol soluble polyurethane (APU) and polyacrylonitrile (PAN) led to large-area fluorescent CDs-embedded nanofiber films, APU/CDs (size: 120 cm × 18 cm) and PAN/CDs (size: 120 cm × 22 cm), respectively. The resultant large-area APU/CDs and PAN/CDs nanofiber films have dramatically enhanced mechanical properties, to show integrated improvement of tensile strength and elongation.