The exploitation of functional phosphors possessing a variety of advantages including narrow-band emission, fast response to near-ultraviolet (n-UV)/blue light excitation, high quantum efficiency, and low thermal quenching, will be essentially...

In this work, three different sulfur sources such as sulfur powder, sodium sulfide, and sodium thiosulfate are selected to prepare sulfur-derived quantum dots (S-QDs), Na 2 S-derived nanoparticles (NS-NPs), and Na 2 S 2 O 3 − -derived QDs (NSO-QDs) in the presence of NaOH or assisted by hydrogen peroxide etching. The low sulfur percentage in the above three samples and the synthesis experiments in the presence of nitrogen/oxygen all support that poly(ethylene glycol) (PEG) plays an important role during the assembly process and the definition of sulfur dots is not accurate. For photophysical features, remarkable green quantum dots (S-QDs) possess an excitation-independent emission peak at 500 nm. But NS-NPs and NSO-QDs demonstrate observable shift tendency, and the evolution of emission profiles varies from 480 to 586 nm. NSO-QDs can be used as a fluorescent probe for highly selective and quantitative detection of Ni 2+ in an aqueous solution in the presence of potential interfering ions with a low detection limit (0.18 μM) and a wide linear range (8−380 μM). Their reusability performance has also been demonstrated by employing dimethylglyoxime as the restoration reagent.

Treatment of sulfur dots with polyethylene glycol (PEG) has been an efficient way to achieve a high luminescence quantum yield, and such a PEG-related quantum dot (QD)-synthesis strategy has been well documented. However, the polymeric insulating capping layer acting as the “thick shell” will significantly slow down the electron-transfer efficiency and severely hamper its practical application in an optoelectric field. Especially, the employment of synthetic polymers with long alkyl chains or large molecular weights may lead to structural complexity or even unexpected changes of physical characteristics for QDs. Therefore, in sulfur dot preparation, it is a breakthrough to use short-chain molecular species to replace PEG for better control and reproducibility. In this article, a solvent-type passivation (STP) strategy has been reported, and no PEG or any other capping agent is required. The main role of the solvent, ethanol, is to directly react with NaOH, and the generated sodium ethoxide passivates the surface defects. The afforded STP-enhanced emission sulfur dots (STPEE-SDs) possess not only the self-quenching-resistant feature in the solid state but also the extension of fluorescence band toward the wavelength as long as 645 nm. The realization of sulfur dot emission in the deep-red region with a decent yield (8.7%) has never been reported. Moreover, a super large Stokes shift (300 nm, λex = 345 nm, λem = 645 nm) and a much longer decay lifetime (109 μs) have been found, and such values can facilitate to suppress the negative influence from background signals. Density functional theory demonstrates that the surface passivation via sodium ethoxide is dynamically favorable, and the spectroscopic insights into emission behavior could be derived from the passivation effect of the sulfur vacancy as well as the charge-transfer process dominated by the highly electronegative ethoxide layer.

The strategy to enhance phosphor stability against thermal quenching and moisture conditions will contribute to controlling the feature of phosphor-converted white-light-emitting diodes (pc-WLEDs). Herein, an effective strategy is achieved with the incorporation of Sm 3+ ions, and a robust reddish-orange emission (no thermal quenching up to 498 K) is obtained based on Ba 3 LaNb 3 O 12 as a host. In light of excitation by near-ultraviolet irradiation at 408 nm, Ba 3 LaNb 3 O 12 :Sm 3+ gives rise to a typical signal ascribed to the 4 G 5/2 → 6 H J/2 (J = 5, 7, 9, and 11) transitions of Sm 3+ ions. The concentration quenching effect is observed when the Sm 3+ content exceeds 10%, and the quenching mechanism is caused by electronic dipole−dipole interactions. Based on the narrow emission curves, a very high color purity (92.4%) could be recorded. The Sm 3+ substitution at the Ba 2+ /La 3+ site leads to a rigid structural lattice and abundant electron-trapping centers for the Sm 3+ ions, which will be responsible for the zero-thermal-quenching phenomenon. In addition, oleic acid (OA) is selected to form a hydrophobic covering surface structure to protect Ba 3 LaNb 3 O 12 :Sm 3+ , which can assist in improving the moisture resistance. The most favorable parameters concerning the warm-light emission (a high general color rendering index, Ra, of 85.7 and a low correlated color temperature, CCT, of 4965 K) can be achieved in pc-WLEDs containing an OA-modified sample. Moreover, its luminous efficiency, LE, can maintain 82.9% of its initial value after 120 h under controlled environmental conditions of 85 °C and 85% humidity. These results pave a new way to optimize the sample as a potential candidate for red-emitting materials.

Two-dimensional platforms with favorable features are highly expected for diverse application. In this work, we report a highly sensitive and selective "turn-on" uorescent nanoprobe for prostate-speci c antigen (PSA) detection base on cobalt oxyhydroxide nanosheets (CoOOH NSs). CoOOH NSs are employed as the suitable sensing hosts, in which uorescein amidite-(abbreviated as FAM) labeled aptamer probe (PA) has been adsorbed on nanosheets. Energy transfer between substrate and optical species has switched off the uorescence of PA. The strong a nity of PA to the target PSA induces the formation of a rigid aptamer structure and the integration with the CoOOH NSs has been drastically affected. The recognition process has been followed by the release of the aptamer probe PA from the nanosheet surface and the green luminescence has been recovered. The dynamic nano-sensor exhibits highly sensitive and accurate analytical performance toward PSA with a linear detection range from 0.1 to 5 nM and a detection limit of 56.1 pM. Therefore, a simple and e cient sensing platform for the detection of prostate cancer can be established.