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Fluorescent carbon dots are a promising drug carrier and bio‐sensor material. The study between human serum albumin and carbon dots could explore the possible interaction mechanism. In this paper, melamine was adopted as passivating agent and citric acid as carbon source, high fluorescence nitrogen doped carbon dots (N‐CDs) were synthetized by one‐pot solid phase pyrolysis successfully. The obtained blue emissive N‐CDs with an average particle size of 2.8 ± 0.7 nm displayed an excitation‐dependent photoluminescence behavior, and the fluorescence quantum yield was estimated to be 12.8%. Moreover, the N‐CDs contained abundant hydroxyl, carboxyl, and amine groups. The molecular interaction between as‐prepared N‐CDs and HSA was systematically investigated in vitro through several spectroscopic methods associated with cyclic voltammetry (CV) and molecular docking. The quenching mechanism of HSA by N‐CDs was static through forming the HSA‐N‐CDs complex, and both hydrogen bonding and van der Waals forces were the fundamental driving forces in the spontaneous binding process. The distance between N‐CDs and HSA was 2.2 nm on the basis of Förster's theory. The competitive binding experiment showed that the binding of N‐CDs was primarily in site I of HSA. Through the analysis of circular dichroism (CD), synchronous fluorescence, and three‐dimensional fluorescence spectra, the secondary structure of HSA was altered in the presence of N‐CDs and the polarity around the amino acid residues of HSA was not changed. Besides, molecular simulation was applied to determine the possible binding situation. Our study explored the interaction mechanism of N‐CDs with HSA, which provided some valuable information for understanding the structure and function of proteins as well as the transport and metabolism of N‐CDs.

Ce3+-doped series of Ca2Al2SiO7 and Sr2Al2SiO7 are prepared via conventional high-temperature solid-state reaction method and impact of Ce3+ doping on Fracto-mechanoluminescence (ML) and Photoluminescence (PL) properties of Ca2Al2SiO7 and Sr2Al2SiO7 was analyzed. Identification of phase formation was done by XRD. Analysis of PL studies reveals that both phosphors emit broadband in the intense blue region, when excited by near-UV light (356 nm), and for further analysis, the emission band was resolved into two peaks, which was attributed to 2D3/2 → 2F5/2 and 2D3/2 → 2F7/2 transitions of Ce3+ ion. The calculated energy difference between these two peaks was found to be 1979 cm−1 and 2037 cm−1, which were in good agreement with the theoretical energy difference (~ 2000 cm−1). The color purity of prepared phosphors was much better than commercial BAM (BaMgAl10O17: Eu2+) phosphor. ML studies were also performed and effect of radiation dose on ML sensitivity has been studied. Results suggest that synthesized phosphors were applied to damage sensors and display devices.

Fluorescent sensing of temperature in nanoscale regions has many advantages and applications in the biological field. Herein, blue emitting carbon dots (CDs) are designed and successfully developed using a one step hydrothermal method. As synthesized CDs exhibit temperature dependent photoluminescent (PL) intensity and PL decay lifetime over the physiological temperature ranging from room temperature (RT) to 70 °C. The PL intensity and PL decay lifetime of the obtained CDs correlate linearly to temperature (RT-70 °C) with correlation coefficient of 0.997 and 0.996, respectively. Additionally, dual mode thermal sensing (PL intensity/lifetime) make these CDs a promising optical nanothermometer over alternative semiconductors quantum dots and CD-based quantum dots. Moreover, the resultant aqueous CDs demonstrate excitation-independent blue emission, and the PL quantum yield (QY) is reached at 44.5%. The obtained CDs illustrate stable performance to high ionic environments and photobleaching even after keeping them for 2 h under continues UV irradiation. Furthermore, blue emitting CDs have low cytotoxicity for T-ca. cells and illuminate deep blue fluorescence under the excitation of 406 nm. As a result, high thermal sensitivity of these fluorescent CDs has potential to detect temperature in living cells in the range of 25-40 °C.

Recently, quantum dots (QD) and quantum rods (QRs) have become extremely popular in displays and lighting applications. Liquid crystal displays (LCDs) equipped with quantum dot enhancement films (QDEFs) offer extended color saturation, increasing said saturation from 60 to 70% to more than 100% of the NTSC color gamut. A plethora of research dealing with EL/PL properties and the device-based performance of these materials has been published. The tunable emission wavelength and the narrow emission bandwidth are the key features of quantum dots and perovskite nanoparticles that primarily depend on the nanoparticle size and material composition. QRs, in contrast, have a core–shell structure and emit polarized light that can roughly double the efficiency of modern displays. However, blue emission for QRs, because of the large bathochromic redshift during shell growth, is a serious problem. Besides photoluminescence, electroluminescence is also important for display applications. These QD-LEDs show a lower turn ON voltage in comparison to organic LEDs, which is very important for high-resolution displays. The solution-processed narrower emission QD-LEDs have already achieved efficiency and a brightness comparable to vacuum-deposited phosphorescent organic LEDs (OLEDs). However, the blue-emitting nanoparticles and their short operational lifetime are the key obstacles in the progression of these devices. Furthermore, recently the display and lighting industry are trying to reduce the short-wavelength emissions, particularly in the spectral region below 455 nm, which has a much greater impact on human ocular health and circadian rhythm. Thus, industries are aiming at blue light in the spectral range of 460–475 nm. This spectral range is very challenging for nanomaterials because of the limited choice of materials. In this review, we summarize the recent progress made in the blue-emitting nanomaterials with a different morphology and composition. This includes recent developments in low Cd materials. Both the PL and EL properties of these materials have been discussed depending on the NP’s shape and material composition. This review also aims to discuss the various device architectures employing blue-emitting NPs, any recent achievements and future challenges.

A highly efficient blue-emitting phosphor of Sr[B8O11(OH)4]:xEu2+ was synthesized though a medium-high temperature boric acid melting method by means of a self-reduction mechanism. The quantum yield and color purity of Sr[B8O11(OH)4]:6%Eu2+ are both as high as 99%. The PL intensity of Sr[B8O11(OH)4]:6%Eu2+ at 150 °C remains 84% of that at 25 °C.

The search for efficient and stable new blue luminescent compounds is still ongoing. In this respect, knowledge of the structure–property relationship is essential for the design and evaluation of blue emitting materials. However, several uncertainties still exist, such as crystal packing and intermolecular interactions, that can significantly complicate the design process. The application of fluorescence lifetime imaging microscopy in combination with Hirshfeld surface analysis for the characterization of luminescent materials are powerful tools that can be used to investigate the structure–property relationship in an emitting substance. However, they have been vastly underutilized in this field. Our results, based on exemplary, new, functionalized phosphine oxides, show that indeed general trends concerning the relationship between photoluminescence lifetimes, emitted light intensities, attractive intermolecular interactions and overall morphology of a compound can be derived through the combination of both analytical methods.

In recent years, efforts have been made to develop narrow-band emission phosphors with excellent performance. Herein, a series of KScSr1−yCaySi2O7:0.07Bi3+ narrow-band phosphors were synthesized by a co-substitution method, and the crystal structure, the occupancy of activated ions and luminescence properties were studied in detail. The substitution of Ca2+ for Sr2+ ions resulted in the migration of the activated Bi3+ from the K site to Sr site, accompanied by the regulation of the emission peak from 410 nm to 455 nm, the peak emission half width from 52 nm to 40 nm, and the color purity from the original 78% to 88%. In addition, a warm white LED with low CCT = 3401 K, CRI = 95.5, and CIE color coordinates of (0.3447, 0.3682) has been obtained through the combination of KSS0.6C0.4S:0.07Bi3+ with a commercial green and red phosphor on a UV (370 nm) chip. The results not only provided a strategy based on the manipulation of chemical composition and crystal structure to tune spectral distribution, but also broadens the choice of activators of narrow-band blue-emitting phosphors.

A near-ultraviolet (NUV) blue-emitting phosphor Ba9 Al2 Si6 O24 :Ce3+ (BAS:Ce3+ ) was synthesized using a high-temperature solid-state reaction. BAS:Ce3+ had an excitation band peak at about 328 nm and showed a blue emission band. The NUV-blue emission band had a peak at about 386 nm with a band width of about 60 nm, attributed to the 5d-4f transition of Ce3+ . Fluorescent decay showed an exponential model with a lifetime of 27.2 nsec. At 150°C, the luminescence intensity decreased to 68.7% compared with the intensity at room temperature.

The concentration dependence of amplified spontaneous emission (ASE) and lasing characteristics in the blend of blue emitting poly(9,9-dioctylfluorene) (PFO) and ladder-type poly(indenofluorene) (2...

Blue-emitting gels are scarce, especially oligomeric/polymeric systems. Here, a series of 4,4′-sulfonyldiphenol (SDP) based oligourethane derivatives (OUs), namely OUHDI, OUHMDI and OUTDI based on 1,6-hexamethylene diisocyanate, 4,4′-methylenebis(cyclohexyl isocyanate) and 2,4-diisocyanatotoluene, respectively, were rationally designed and obtained by simple procedures. The new oligomers all display aggregation-induced blue fluorescence and upon gelation they achieve enhanced bright deep-blue emission as a result of interchain hydrogen bonding and oxygen cluster interactions. The OUs show spontaneous thermoreversible gelation in solvents which possess hydrogen-bond receptor units (C[double bond, length as m-dash]O or S[double bond, length as m-dash]O) which facilitate self-assembly of the OU chains into nanotubes. The oligourethane gels (OUGs) possess excellent ability for resisting external stress while at the same time exhibiting a distinct viscous flow state. The results illustrate that heteroatomic non-conjugated oligomers with advantageous hydrogen bonding interactions and oxygen clusters provide an efficient route to photoluminescent blue-emitting gels. The thermoreversible OUGs with excellent mechanical properties have been exploited to make sticky coatings, transparent films and a blue fluorescent molded shape using simple fabrication processes.

We have implemented both the Dornauf–Heber (D–H) model and a brute force statistical (BFS) model to characterize the quenching by neighboring Er and Yb ions of the green and blue emitting states of...

Currently, exciplex-based materials had drawn attention of its potential for efficient electroluminescence or for use as a host. In this study, we use TCTA and TmPyPB to form an exciplex host and FIrpic were used as dopant to emit blue phosphorescent light. The mixed ratio of the host was selected to improve the current efficiency of the device and used various types of data to investigate the most important factors affecting efficiency (such as photoluminescence, single carrier device, and electroluminescence). We found out the ratio 1:2 was the preferable ratio in this study. The devices with mixed ratio 1:2 have pretty high current efficiency (56 cd/A).

A Series of blue emitting organic phosphors and its derivatives with different combinations were synthesized in an argon atmosphere at 1400C by Friedlander Condensation method and are tested chemically for its solubility in acidic and basic and emitting blue color under UV. The structural changes take place in DPQ an organic phosphor. The structural, optical and chemical properties of all the derivatives of diphlnylquioline (DPQ) were studied from various characterizations. It shows the stability of characterized organic polymers. The physical and chemical study shows more effectiveness with large applications to emit blue light for organic display system.

In this study, a simple environmental benign approach have been adopted for the preparation of highly luminescent (blue emitting) water soluble carbon nano-dots using Pongammia pinnata (Pp) leaves via hydrothermal technique. The prepared Pp-carbon nano- dots were characterized using UV-vis spectroscopy, fluorescence spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements. The Pp-carbon nano-dots are spherical in shape with an average size of 32 nm.

International audience; White light emitting diodes (wLEDs) have become, in the last decade, the most efficient device for most lighting applications. They are mainly composed of indium and gallium for the blue emitting LED, and rare-earth elements for the phosphor producing the yellow component of the white light. Those elements are crucial to achieve the excellent lighting properties of wLEDs, but they are systematically ranked among the most critical materials. In the present review, the essential roles of indium, gallium and rare-earth elements in wLEDs are specified, and their criticality through the main criteria of supply shortage risk and economic importance is discussed in detail in the light of the wLED market. The opportunities and technological challenges of their reduction using nano-sized objects and substitution using non-critical materials are considered in relation to the resulting changes in the performance of wLEDs, but also to the stated preference of consumers of the final product, creating an opportunity for trade-offs between the performance and avoidance of critical materials in wLEDs. The economic value that a consumer could place in a critical material-free wLED is further estimated through a choice experiment conducted with 297 consumers. The results obtained show a positive, significant willingness to pay for critical material-free wLEDs. On average, consumers are ready to pay €2.82 more for a wLED sold at €10. The present approach addresses the transdisciplinary problem of the reduction and substitution of critical materials in functional devices intended for consumers, and can be generalized to other energy-related materials and devices.

Colloidal all-inorganic perovskite CsPbBr3 nanocrystals present versatile outstanding optoelectronic properties as well as greatly improved stability when compared with their hybrid analogues. Howe...

A series of challenging issues such as field-driven spectral drift for the CsPbClxBr3–x system and mixed phases in quasi-two-dimensional structures still exist when devising blue-emitting perovskites. In this Letter, the CsPbBr3 quantum-dot (QD) system is proposed to overcome these challenges. However, to date, the CsPbBr3 QD films with tunable colors from green to blue still cannot be achieved using existing methods. Herein, a simple one-step spin-coating route incorporated with efficient ligand passivation is developed to realize this goal. The size restriction of CsPbBr3 QDs is enabled by a diammonium ligand, propane-1,3-diammonium bromide (PDAB). A mixed-ligand system of phenethylammonium bromide (PEAB) with PDAB is further explored to enhance their optical performance. The CsPbBr3 QDs experience a second growth process upon controlled air exposure, which is utilized to realize their size control and emission wavelength tunability. The CsPbBr3 QD-based devices exhibit no spectral drift in electroluminescence under voltage bias.

Among the lead halide perovskites, photoluminescence quantum yield (PLQY) of violet-emitting CsPbCl3 nanocrystals (NCs) is the lowest (

Recently, interest in developing efficient, low-cost, nontoxic, and stable metal halide emitters that can be incorporated into solid-state lighting technologies has taken hold. Here we report nonto...

Luminescent phosphorene quantum dots (PQDs) have emerged as fascinating nanomaterials for potential applications in optoelectronics, catalysis, and sensing. Herein, we investigate the structural distortion of black phosphorus (BP) under an applied electric field to yield blue luminescent PQDs [average diameter 8 ± 1.5 nm ( N = 60)]. The electrosynthesized PQDs exhibit photoluminescence emission independent of excitation wavelength with 84% quantum efficiency. Structural distortion that occurred during the transformation of BP to PQDs is confirmed by results obtained during transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Further, using first-principles-based density functional theory, calculations on oxygenated and nonoxygenated PQDs augment the experimental observations that an optimum oxygen content maintains the structural integrity of PQDs, above which the structural robustness of PQDs is drastically diminished.

Disclosed herein is a highly efficient one-pot synthetic strategy to phenanthrone-type polyheterocycles via tandem rhodium(III)-catalyzed ortho-C–H heteroarylation of indolyl ketones and copper(II)-promoted intramolecular cyclization. This protocol enables a library of blue-emitting fluorophores with high quantum yields and narrow full widths at half-maximum to be rapidly built from readily available substrates, among of which 6,6,7,9,12-pentamethyl-6,12-dihydro-5H-benzofuro[2,3-a]carbazol-5-one (4a) exhibits pure blue emission with Commission Internationale de I’Eclairage coordinates of (0.15, 0.09) and a high quantum yield of 85% in CH2Cl2 solution.

A series of novel luminescence phosphors Ca9La(PO4)5(SiO4)Cl2:xEu2+ (CLPSCl:Eu2+) with apatite structure have been synthesized by a high temperature solid-state reaction. The phased purity of as-prepared phosphors was verified through XRD technique. For further discussion, a series of analysis were performed such as the photoluminescence emission and excitation spectrum and decay lifetime to identify the luminescent properties of CLPSCl:Eu2+ phosphors. The CLPSCl:Eu2+ displays broad excitation spectra ranging from 250 to 450 nm, and intends emission intensity at 461 nm under 345 nm. The optimum Eu2+ concentration of CLPSCl is 8 mol%. The luminescence decay lifetime of the optimum phosphors was measured to be 275 ns. All of the results obtained highly indicate that CLPSCl:Eu2+ is potentially blue-emitting phosphor for application in white LEDs.

We have synthesized blue emitting compounds, DBI-SFX and SBF-SFX, by incorporating fluorene-9,9'-xanthene as main chromophore and introducing 1,2-diphenyl-1H-benzoimidazole and spirobi[fluorene] gr...

Efficient blue, green and red phosphorescent OLEDs have been harvested from silver nanoparticles embedded at a glass:Ga–Zr-codoped TiO2 interface. The embedded silver nanoparticles at the interface removed the non productive hole current and enhanced the efficiencies. The blue emitting device (456 nm) with emissive layer Ir(fni)3 exhibits a maximum luminance (L) of 40 512 cd m−2 (ITO – 37 623 cd m−2), current efficiency (ηc) of 41.3 cd A−1 (ITO – 40.5 cd A−1) and power efficiency (ηp) of 43.1 lm w−1 (ITO – 39.8 lm w−1) and external quantum efficiency (ηex) of 19.4% (ITO – 6.9%). A newly fabricated green device based on emissive layer Ir(tfpdni)2(pic) shows intensified emission at 514 nm, luminance of 46 435 cd m−2 (ITO – 40 986 cd m−2), current efficiency of 49.7 cd A−1 (ITO – 47.3 cd A−1), power efficiency of 48.6 lm w−1 (ITO – 41.4 lm w−1) and external quantum efficiency of 17.5% (ITO – 14.9%). The red device (618 nm) with emissive layer Ir(bbt)2(acac) shows luminance of 8936 cd m−2 (ITO – 8043 cd m−2), current efficiency of 6.9 cd A−1 (ITO – 4.6 cd A−1), power efficiency of 5.7 lm w−1 (ITO – 4.9 lm w−1) and external quantum efficiency of 9.3% (ITO – 6.9%).

Fully inorganic lead halide perovskite materials have attracted tremendous attention because of their practical applications in optoelectronic devices, such as light emitting diodes. In this work, we report the first development of highly efficient, stable and green-emitting CsPbBr3 perovskite NCs with a PE microcapsule. The CsPbBr3 perovskite NCs were perfectly incorporated inside the PE microcapsule with a multi-lamellar structure, which shows better luminescence characteristics such as a high PLQY and thermal stability Furthermore, our results revealed the high luminous performance with a white conversion efficacy of 62.4 lm W−1, EQE of 31.8%, CRI of 37.01, and CCT of 6028 K on blue emitting InGaN LED chip. We suggest that our material will be one of the next generation candidate luminescence materials for application in optoelectronic devices.

Objectives Purpose of this research was to find the best blue-emitting fluorescent substance for plastic scintillator used for gamma radiation dosimetry. Scintillator should convert gamma radiation into blue light with high efficiency. Methods Plastic scintillators with fixed concentration of various fluorescent additives, called wavelength shifters, absorbing ultraviolet light and emitting blue light were manufactured by radical bulk polymerization of styrene. Light output were measured and compared to the light output of commercial plastic scintillator. Results Performed measurements of charge Compton spectra confirmed usefulness of majority of researched substances as wavelength shifters in plastic scintillators with emission maximum at blue range of visible light. Conclusions Plastic scintillation dosimeter may be constructed from manufactured polystyrene-based scintillators. Performance of synthesized scintillators is close to commercial polystyrene scintillators.

International audience; We report a series of blue fluorophores based on the dispiro[fluorene-9,6 '-indeno[1,2-b]fluorene-12 ',9 ''-fluorene] (DSF-IF) scaffold. The DSF-IF scaffold, introduced in 2006 in the literature for organic electronic applications, is nowadays a very useful building block to construct functional materials. However, the functionalization of the DSF-IF scaffold has been poorly investigated to date. In this work, we focus on three different molecular architectures incorporating at each extremity of the central dihydroindenofluorenyl core either an electron accepting unit (A-pi-A), an electron donating unit (D-pi-D) or one of each (D-pi-A). The different substitutions of the dihydroindeno[1,2-b]fluorenyl core has allowed the strong modulation of the properties of the dyes and the precise study of the effect of this fragment as a pi-conjugated bridge.

The lack of highly efficient blue‐emitting perovskite nanocrystals limits their development for optoelectronic applications. In article number 2001698, Bartomeu Monserrat, Shuyu Zhang, and co‐workers develop blue‐emitting neodymium‐doped CsPbBr3 nanocrystals with high photoluminescence quantum yield (PLQY) and narrow spectral width. First principles calculations reveal the microscopic mechanisms for the blueshift of photoluminescence and the enhancement of PLQY upon doping. [Image: see text]

Communication characteristics of high-brightness solid-state light sources based on luminescence concentration generated using blue emitting InGaN light emitting diode arrays are demonstrated here for the first time. The proposed device is used as a transmitter in visible light communications, and its performance is evaluated.

Disclosed herein is a rhodium-catalyzed oxidative C–H activation/domino annulation of N-Boc-anilines with 1,3-diynes for the construction of tricyclic N,O-heteroaromatics. This reaction features ea...