Cadmium based chalcogenides (CdS, CdSe, CdTe) quantum dots exhibited ultrahigh photoluminescence (PL), quantum yields (QYs) and multicolor luminescence. However, the usual synthesis needs high temperature, inert gas protection, and localized injection operation, which hinder applications seriously. Here, we synthesized CdS QDs and a series of metal-ions-doped QDs using low temperature synthesis (30–80 °C). The synthesis was designed according to supersaturated recrystallization. It was operated under air atmosphere, in DMF solution, free from inert gas protection and used non-injection operation. The obtained QDs exhibit strong and stable luminescence. They have a monodisperse, uniform morphology and good crystallinity. With increasing synthesis temperature, the emission center of the CdS QDs shifts from 500 nm to 550 nm. The metal ions doped in the CdS substrate form a deep level. The emission energy decreases and the emission center shifts to longer wavelengths. The emission peaks located at 520 nm, 534 nm, 540 nm, 578 nm and 625 nm correspond to CdS QDs doped with Sn2+, Sb3+, Ni2+, Mn2+ and Cu2+, respectively. The increased synthesis temperature also results in a red shift of the emission peak. The tunable optical properties and the suitability for large scale production endow the metal-ions-doped CdS QDs with promising potential for lighting and displays, which was demonstrated by white light-emitting diodes with a high CRI value, power efficiency and good stability.

Transition metal sulfides are a kind of potential candidates for efficient and stable CE materials in DSSCs due to their good electrocatalytic ability and stability towards I3− reduction. However, the low conductivity of sulfides is harmful for the electron collection and transfer process, and the absorption/desorption and diffusion process of I−/I3− should be optimized to achieve high electrocatalytic activity over Pt. Herein, a hierarchical CoFeS2/reduced graphene oxide (CoFeS2/rGO) composite was rationally designed and prepared via the in situ conversion of CoFe layer double hydroxide anchored on rGO. Due to the synergistic effects of Co and Fe, unique 3D hierarchical structures formed by nanosheets, and the conductivity of rGO, the CoFeS2/rGO CEs exhibited good electrocatalytic activity and stability towards the reduction of I3− to I−, and the DSSCs could also achieve a high efficiency of 8.82%, higher than those of the devices based on Pt (8.40%) and pure CoFeS2 (8.30%) CEs. Moreover, the devices also showed the characteristics of fast activity onset, good stability, and high multiple start/stop capability. The results indicated that the developed CoFeS2/rGO composite could be a promising alternative for Pt in DSSCs.

In this paper, mesoporous antimony doped tin oxide (ATO) microspheres are synthesized via a solvothermal method from a methanol system with the surfactant followed by a thermal treatment process. Morphology studies reveal that the spherical products obtained by polyvinylpyrrolidone (PVP) templating result in a higher uniformity in size. Such obtained ATO microspheres with a secondary particle size ranging between 200 and 800 nm consist of packed tiny nanocrystals and have high specific surface area (∼98 m2 g–1). The effect of Sb doping on the structural and electrical properties of SnO2 microspheres is studied. Because of the substitution of Sn4+ with Sb5+ accompanied by forming a shallow donor level close to the conduction band of SnO2, a lower resistivity of powder pellet can be achieved, which corresponds to the spectrally selective property of films. The application of ATO microspheres provides an example of transparent coatings; depending on Sb concentration in SnO2 and solid content of coatings, transparent films with tunable solar-heat shielding property are obtained.Keywords: antimony doped tin oxide (ATO); mesoporous microspheres; methanol; solar-heat shielding; solvothermal route; transparent thin films

Highly efficient Cr3+- and Yb3+/Nd3+-co-activated YAl3(BO3)4 (YAB) phosphors have been developed as spectral convertors for improving silicon solar cell photovoltaic conversion efficiency. In the YAB lattice, Cr3+ ions act as broadband spectral sensitizers by absorbing UV-Vis (370–750 nm) photons, which are not absorbed by the silicon solar cell. After energy transfer, the Yb3+ acceptors then exhibit strong NIR emission centered at around 1000 nm, which is coupled well with the absorption band of the silicon solar cell. Efficient energy transfer is reflected by a sharp decrease in the excited state lifetime and red photoluminescence (PL) from Cr3+ with increasing Yb3+ concentration. Further evidence in favor of energy transfer is that PL-excitation spectra of NIR luminescence from Yb3+ are identical to those of deep red emission from Cr3+. Trivalent ions Gd3+, Bi3+ and La3+ have been introduced into YAl3(BO3)4:Cr3+,Yb3+ in this study for a stronger NIR PL intensity. Additionally, energy transfer from Cr3+ to Nd3+ is also observed. Yb3+,Nd3+-co-activated YAB shows much broader NIR emission. Due to the effective absorption of Cr3+ in the visible region in YAB and the efficient energy transfer to Yb3+/Nd3+, these materials can be developed as spectral convertors to improve silicon solar cell photovoltaic conversion efficiency.

We propose a composite mono-Si solar cell integrated with CdO nanotips (NTs). The substrate was mono-Si with a Si3N4 antireflection (AR) layer already deposited on the top. CdO NTs were synthesized on the surface of the Si3N4 AR layer by chemical bath deposition (CBD). The CdO NTs composite solar cell achieved a 14% enhancement in power conversion efficiency (PCE) compared to the cell without CdO NTs. The J–V curve, reflectance, and photoluminescence demonstrate that the remarkable antireflection and down-conversion of CdO NTs, and the slightly increased fill factor played significant roles in the increased PCE. We believe that the PCE of Si solar cells still has scope for improvement by adding materials with proper antireflection, down-conversion and conductivity properties to the top of the cells.

Effective CdS/ZnO nanorod arrays (NRAs) as antireflection coatings for light trapping in c-Si solar cells were prepared by a chemical bath deposition method which is a mature technology suitable for mass production. Field emission scanning electron microscopy (FESEM) reveals that CdS nanoparticles with a diameter of ∼65 nm are deposited on the top of ZnO NRAs with an average length of 380 nm and a diameter of ∼40 nm. The cell with CdS/ZnO NRAs coatings exhibits lower reflectance and better light trapping ability than the cell with ZnO NRAs. PL spectra reveal that the formation of CdS nanoparticles can suppress the outward broad defect emission of ZnO NRAs peaking around 575 nm so that green-yellow light emission of ZnO NRAs can be transmitted into c-Si solar cells for photovoltaic conversion. The J–V curves obtained under the AM1.5G simulator illumination conditions further indicate the improved photovoltaic properties of c-Si solar cells due to CdS/ZnO NRA antireflection coatings.

A composited colloidal Si nanocorals (NCs)/PbS quantum dots (QDs) p–n active layer was demonstrated to have the potential to reduce the surface recombination velocity and further improve the cell efficiency, not only due to the light trapping structure of Si NCs, but the ability of passivation as well as down-conversion in PbS QDs. An appropriate length of Si NCs was acquired first by investigating the interaction of light absorption and effective minority-carrier lifetime. After the integration with PbS QDs, the composited solar cell showed a 30% increase in power conversion efficiency (PCE), compared to its bare Si substrate counterpart. Thus, we believe that the Si NCs and PbS QDs composited structure is promising for the enhancement of the PCE of current Si based photovoltaic devices.

A highly efficient yellow oxyfluoride phosphor Sr2.97−1.5xCaxAl1−2yMgySiyO4F:0.02Ce3+ has been developed as a component of solid state white light emitting diodes (LED). The phosphor emits with a maximum at 545 nm when excited by 430 nm with a quantum efficiency approaching 84%. After substituting magnesium and silicon into the aluminum sites, replacing the strontium by calcium in Sr3AlO4F:Ce3+, we discovered a class of single phase materials. This results in the emission maximum redshift from 460 nm to 545 nm and the excitation red shift from 400 nm to 430 nm (compared with Sr3AlO4F:Ce3+). The combination of an InGaN LED chip (λmax = 430 nm) had a color temperature of about 4500 K and the color rendering index was 78. This phosphor has potential for incorporation into near-UV white LEDs and related applications.

Three series of BiOMxR1−x (M, R = Cl, Br, I) solid solutions were systematically synthesized through a low-temperature precipitation. These solid solutions were characterized by XRD, FESEM, TEM, EDS, UV-vis spectra, nitrogen sorption/desorption, and PL. The tunable band gaps of the as-prepared solid solutions were realized via only changing the molar ratio of two halide ions. Meanwhile, the influence of citric acid in the formations of controllable morphological structures was discussed to study the growth mechanism of solid solutions. The photocatalytic activities of the bismuth oxyhalide solid solutions have also been investigated by the degradation of Rhodamine-B (RhB) under visible light irradiation. The optimized solid solutions possess higher photocatalytic activity than pure ones [BiOM (M = Cl, Br, I)] due to the broadened range of visible light response and the reduced recombination rate of electron–holes pairs. The results show that the synthesis of BiOMxR1−x (M, R = Cl, Br, I) solid solutions have profound significance for the design of the novel photocatalyst materials.

Trivalent ions B3+, Al3+ and Ga3+ have been introduced into Sr3SiO5:Ce3+ in this study. Among these ions, Al3+ and Ga3+ act as charge compensators and significantly enhance the maximum emission of Ce3+ by about 100% and 90%, respectively. Then, Al3+, Eu2+ co-doped Sr3SiO5:Ce3+ phosphors have been researched, which indicate that the emission spectra can be tuned from 530 to 575 nm by changing the concentration of Eu2+. The CIE chromaticity coordinates of the phosphors were calculated from (0.342, 0.518) to (0.442, 0.479). This indicates a potential for applications in daylight LEDs or warm-white LEDs.

Monodisperse ZnSn(OH)6 (ZHS) microcrystallites (MCs) with two morphologies have been prepared through a facile preparation method without complicated steps, or advanced experimental conditions or equipments. The morphology and compositional characteristics of the 3D hierarchitectures (HAs) of ZHS MCs were investigated by various techniques such as XRD, FESEM, TEM, UV-vis spectra, BET, XPS and EPR. In the reaction system the morphology evolution from cube to sphere was controlled by adding a different concentration of NH4OH. Meanwhile, the formation mechanisms of the two ZHS MCs were studied via a series of time-dependent experiments. Interesting, ZHS MCs were self-assembled from irregular-shaped nanoparticles (5–10 nm). The XPS and EPR tests demonstrated oxygen vacancy defects existed in the ZHS MCs. The gas sensors based on ZHS presented a good sensor performance towards HCHO. However, the gas sensors based on of ZHS spherical MCs exhibited a higher response, shorter recovery time and good reproducibility towards HCHO than those of ZHS cubic MCs. More importantly, the best gas sensing properties were found coming from the ∼600 nm spherical ZHS MCs owing to more oxygen vacancy defects, lower band gap energy, and larger active surface area.

Size-tunable Y2O3:Eu3+ flower aggregates constructed from nanotubes were obtained through rolling up Y(OH)CO3 nanosheets under template-free hydrothermal conditions at 200 °C for 2 h, followed by an annealing process. Y(CH3COO)3 was used as a raw material for the preparation of Y(OH)CO3 precursors through urea precipitation. The absorbed CH3COO− ions play an important role in the formation of nanosheet structures and PEG keeps the precursors monodisperse and uniform. Through decreasing the concentration of Y(CH3COO)3, smaller Y(OH)CO3 flower assemblies of fewer nanotubes and homogeneously separated Y(OH)CO3 nanotubes with the length of ∼150 nm and the diameter of ∼40 nm and monodisperse ∼30 nm Y(OH)CO3 nanospheres, respectively, were also selectively prepared. After calcination at 600 °C for 2 h, the Y(OH)CO3 were decomposed into Y2O3 and the tubular structures were maintained. Doped Eu3+ ions don't influence their morphologies. Under UV excitation, Y2O3:0.05Eu3+ flower-like and spherical samples show strong red emission, corresponding to the characteristic lines of Eu3+.

Hollow/flower-like BiOI microspheres have been prepared through a facile precipitation route in a water–ethanol mixed solution with the assistance of PVP and citric acid (CA) at low temperature (70 °C). The obtained products were characterized by a range of methods such as XRD, FESEM, TEM, UV-vis, DRS, PL and nitrogen sorption. A three-stage growth mechanism of such hierarchical hollow/flower-like microstructures has been proposed by observing the XRD analysis and FESEM of the intermediate products at different reaction times. Interestingly, the structure of BiOI from hollow to flower-like could be obtained by only adjusting the different amounts of reagents in the reaction system. The photocatalytic activities of the hollow/flower-like microspheres were evaluated by the degradation of RhB under visible-light irradiation, compared with the nanoplate sample and P25. Although the hollow BiOI microspheres had a higher specific surface area, the flower-like BiOI microspheres exhibited much higher adsorption and photocatalytic activities than the former. This controllable morphology method and particular properties of BiOI hierarchical microstructures could be used to synthesize bismuth-based semiconductors or other structure-controllable materials and to explore remarkable potential applications of their photocatalytic degradation ability.

Iodine-incorporated BiOCl (I–BiOCl) core–shell microspheres were for the first time fabricated using a one-step approach under atmospheric pressure. The morphology and compositional characteristics of the 3D hierarchitectures (HAs) of BiOCl were investigated by various techniques such as XRD, FESEM, TEM, EDS, XPS and PL. On the basis of observing the structure of BiOCl and iodine-containing BiOCl at different intervals of reaction time, a three-stage growth mechanism that involves an initial Ostwald ripening process followed by a self-assembly process is proposed. Meanwhile, iodine anions were utilized as both structure-directing agents for fabricating hollow, core–shell, solid structure and doped ions incorporated into the framework of the core–shell BiOCl spheres to extend the light adsorption edge to the visible light region. UV-vis spectra reveal that the band energies of the iodine anions-modified BiOCl (I–BiOCl) hierarchical hollow, core–shell, and solid samples (2.43 eV, 2.28 eV and 2.04 eV, respectively) exhibit obvious red-shifts with respect to that of the pure hollow BiOCl sample (3.23 eV). I–BiOCl without adding poly(vinylpyrrolidone) (PVP) was researched. This result demonstrated that the formation of the core–shell structure is induced by a synergetic effect by iodine and PVP. The specific surface area and porosity of the iodine anions-modified hierarchical BiOCl were also investigated by using nitrogen adsorption–desorption isotherms. The as-prepared I–BiOCl core–shell microspheres showed much higher photocatalytic activity than that of the reported TiO2−x−yNxFy(SC)-3 and Bi2WO6, which was evaluated by the degradation of phenol under visible light (λ > 420 nm) and Rhodamine-B (RhB) dye under visible light (λ > 420 nm) and sun-light irradiation.

Nearly monodisperse NaY(MoO4)2 architectures with various shapes have been selectively prepared on a large scale by a capping agent free hydrothermal process using Y(OH)3 nanorods as a precursor. The molar ratio of Na2MoO4/Y(OH)3, the volume ratio of water/ethanol in the mixed solvents and temperature have comprehensive and crucial influences on the formation of multi morphologies of NaY(MoO4)2. The formation of multi morphologies is explained mainly from the viewpoint of the effective concentration of MoO42− ions. At high temperature, high Na2MoO4/Y(OH)3 ratio and high water/ethanol volume ratio, the effective concentration and reactivity of reactants, especially MoO42− ions, are improved, which is beneficial to the growth of 3D NaY(MoO4)2 architectures. Under UV excitation, without further annealing treatment, NaY(MoO4)2:0.05Eu3+ bipyramid micro samples show strong red emission, corresponding to the characteristic lines of Eu3+.

Bismuth oxychloride (BiOCl) sub-microcrystals with tunable morphologies from nanoflakes to hollow microspheres (HMSs) have been synthesized by hydrolyzing a hierarchical precursor (BiCl3) in a solution of water and ethanol with the addition of poly(vinylpyrrolidone) (PVP) and citric acid. The obtained BiOCl possessed sub-microcrystals from single crystals to polycrystals. The formation of the nestlike and hollow structure was found to be induced by citric acid and PVP. The crystal growth and morphology control of BiOCl were explored. Interestingly, citric acid was utilized both as a crystal-growth-inducing agent and a structure-directing agent. The morphology and compositional characteristics of BiOCl were investigated by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Raman, and UV–vis spectra. The photocatalytic activities of BiOCl with different structures have also been investigated by the degradation of Rhodamine-B (RhB) dye under ultraviolet light irradiation. The as-prepared BiOCl exhibited much higher photocatalytic activity than the comzmon one. In particular, the three-dimensional hierarchical structure such as microflowers and HMSs can effectively improve photocatalytic activity. The results show that BiOCl sub-microcrystals have promise as a novel material for photocatalytic applications.

Uniform Gd2O2S flower-like nano-assemblies were prepared through one-pot mild solvothermal synthesis. The parallel nanoplates are the building blocks, ∼3 nm in thickness and 20–30 in diameter. Ethanediamine, the main solvent, plays an important role in dissolving a large amount of sulphur and producing active S2− ions, which results in the direct formation of Gd2O2S. Oleylamine, the capping agent, controls the growth of the plate-like structure. Under UV excitation, the Gd2O2S:Eu3+ nano-phosphor shows good red luminescence with a main emission peak at 627 nm. Under 980 nm laser excitation, Gd2O2S:xYb3+,1%Er3+ nano-phosphors exhibit a tuneable emission, shifting from greenish-yellow to orange-yellow, with increasing Yb3+ content.

We report a bifunctional hollow porous microsphere composed of single-component BaMoO4:Pr3+ nanocrystals by a facile template-free synthesis. All the as-synthesized hollow microspheres are well-dispersed with a diameter of 2–4 μm and the BaMoO4:Pr3+ nanocrystals measure 30–60 nm in diameter. It is observed that there are a large amount of pores with an average diameter is 17.5 nm in the shell of these BaMoO4:Pr3+ hollow microspheres, thereby exhibiting a great promise for drug delivery. Meanwhile, the strong, narrow-bandwidth red emission centered at 643 nm from these nanostructures can be efficiently excited from 430 nm to 500 nm. The combination of excellent luminescent properties and a hollow porous nanostructure suggest a great promise in the application of these nanostructures in lighting and displays, and in biomedicine such as targeted drug delivery, integrated imaging, diagnosis, and therapeutics. In addition, the template-free solution synthesis can be applied to the design and fabrication of other functional architectures.

Solid-state reaction is the most common method for preparing luminescent materials. However, the luminescent dopants in the hosts tend to aggregate in the high-temperature annealing process, which causes adverse effect in photoluminescence. Herein, we report a novel europium (II)-doped zeolite derivative prepared by a combined ion-exchange and solid-state reaction method, in which the europium (II) ions are isolated to a large extent by the micropores of the zeolite. Excited by a broad ultraviolet band from 250 to 420 nm, a strong blue emission peaking at 450 nm was observed for these Eu-embedded zeolites annealed at 800 °C in a reducing atmosphere. The zeolite host with pores of molecular dimension was found to be an excellent host to isolate and stabilize the Eu2+ ions. The as-obtained europium (II)-doped zeolite derivative showed an approximately 9 fold enhancement in blue emission compared to that of the general europium (II)-doped aluminosilicates obtained by conventional solid-state reaction, indicating that, by isolating active luminescence centers, it is promising to achieve highly luminescent materials. Also, the strong blue emission with broad UV excitation band suggests a potential candidate of phosphor for ultraviolet excited light-emitting diode.Keywords: ion-exchange; LED; luminophor; photoluminescence; solid-state reaction; zeolite;

An efficient solar reflective thermal insulating coatings (SRCs) based on Y-stabilized Sb2O3 nanoparticles has been prepared via a facile one-pot ball-milling route. Y-stabilized Sb2O3 have smaller particle size (about 5 nm), disperse more evenly in coating films and exhibit higher solar reflectance compared with pure Sb2O3. Y-stabilized Sb2O3 SRCs have the reflectance of more than 90% in the region 450–1600 nm and more than 80% in the region 1600–2200 nm and excellent thermal insulating properties. The observed solar reflectance properties of Y-stabilized Sb2O3 SRCs were explained on the basis of the electronic structure of the material and physical parameters such as mean particle size (crystallite size) and refractive index. Due to its high solar reflectance and excellent thermal insulation properties, as-prepared Y-stabilized Sb2O3 SRCs maybe a promising candidate for the energy saving applications in the constructions and industry furnishment.Highlights► Sb2O3 nanoparticles were prepared via a facile one-pot ball-milling route. ► Sb2O3 based coatings have high solar reflectance properties. ► Sb2O3 based coatings have excellent thermal insulation properties. ► Sb2O3 based coatings may find applications in the energy saving of constructions.

Uniform and monodisperse ZnSnO3 cubic crystallites were prepared via a solution process involving the reaction of zinc sulfate and sodium stannate at a reaction temperature as low as 0 °C without any surfactant. The size was readily controlled from 40 to 600 nm by varying the reaction temperature. The possible formation mechanism of cubic crystallites was attributed to a nucleation assembly process. The as-fabricated sensors based on ZnSnO3 cubic crystallites showed high sensitivity, fast response, and short recovery times toward HCHO gas. And as the particle-size of ZnSnO3 cubic crystallites decrease, the sensitivity of gas sensors based on them increases and the recovery time shorten rapidly. The detection limit of ZnSnO3 cubic crystallites sensor can reach as little as lower than one per million for HCHO. The performance of a home-built ZnSnO3 cubic crystallites sensor was even better than the competing SnO2 and In2O3 sensor, making this material interesting for sensor devices.

An efficient red phosphor, BaMoO4:Pr3+, has been fabricated by a convenient solid-state method. A strong red emission centered at 643 nm corresponding to the 3P0→3F2 transition of Pr3+ is observed under 430–500 nm excitation. In addition, improvement of the intensity of the red emission has been achieved by adding an alkali chloride to the BaMoO4:Pr3+ phosphor samples, this being explained by a charge compensation mechanism. The influence of the sintering temperature on the luminescence properties of the phosphors is also discussed.

A facile process is demonstrated to synthesize ZnO:S,Cl apertured architectures via annealing of the mixture of ZnS and NH4Cl. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), photoluminescence (PL), and photoluminescence excitation (PLE), respectively. The XRD and SEM results indicate that the as-prepared products with high crystallinity and shaped like cakes with the holes (1–5 μm) can be seen clearly on the particles surface. The PL spectrum presents a broad green emission band (450–600 nm) centered at 500 nm, which is attributed to the oxygen vacancies induced by the incorporated S. The PLE spectrum shows a broadening excitation region ranged from 250 to 420 nm, which may result from the incorporation of Cl− ions.

Cl-doped ZnO nanospheres with the average diameter about 60 nm have been synthesized by a wet chemical route followed by annealing in air. The samples were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), photoluminescence (PL) and photoluminescence excitation (PLE) spectra, respectively. The results indicate that Cl-doping in ZnO nanospheres induces a new defect energy level between the luminescent center and the conduction band, which results in considerable enhancement of the green PL intensity.

Sm3+-activated SrZnO2 has been synthesized by gel-combusting method and characterized using X-ray powder diffraction, TEM, TG as well as excitation, and emission spectroscopy. The luminescence properties of this phosphor have been studied. A new zincate compound SrZnO2:Sm3+ is obtained. SrZnO2:Sm3+ crystallizes in an orthorhombic structure with Pnma space group and unit cell with the lattice parameters: a = 5.830 Å, b = 3.340 Å and c = 11.348 Å. These materials can be efficiently excited in the UV to visible region (350–420 nm, main peaks 413 and 380 nm), making them attractive as conversion phosphors for LED applications. A red emission at 600–730 nm (main peaks 607 and 655 nm) is observed for SrZnO2:Sm3+ which is the promising conversion phosphor for white-light LEDs.

Nanocrystalline Y2Si2O7:Eu phosphor with an average size about 60 nm is easily prepared using silica aerogel as raw material under ultrasonic irradiation and annealing temperature at 300–600 °C and this nanocrystalline decomposes into Y2O3:Eu and silica by heat treatment at 700–900 °C. The excitation broad band centered at 283 and 254 nm results from Eu3+ substituting for Y3+ in Y2Si2O7 and Y2O3/SiO2, respectively. Compared with Y2O3:Eu/SiO2 crystalline, the PL excitation and emission peaks of Y2Si2O7:Eu nanocrystalline red-shift and lead to the enhance of its luminescence intensity due to the different chemical surroundings of Eu3+ in above nanocrystallines. The decrease of PL intensity may be ascribed to quenching effect resulting from more defects in Y2O3:Eu/SiO2 crystalline.

The S-doped ZnO microspheres with average diameter of 3 micrometers (μm) have been successfully synthesized by a simple air oxidation process of ZnS precursor. X-ray diffractometer (XRD) pattern indicates that the as-obtained sample is composed of ZnO and ZnS. The scanning electron microscopy (SEM) image shows that the exterior surfaces of the microspheres are composed of many nanoparticles with an average grain size of 100 nanometers (nm). The photoluminescence (PL) spectra show the broad excitation region with the main peak at 370 nm and strong green emission centered at 500 nm, which can be attributed to the oxygen vacancies caused by S replacement of O.

We report a bifunctional hollow porous microsphere composed of single-component BaMoO4:Pr3+ nanocrystals by a facile template-free synthesis. All the as-synthesized hollow microspheres are well-dispersed with a diameter of 2–4 μm and the BaMoO4:Pr3+ nanocrystals measure 30–60 nm in diameter. It is observed that there are a large amount of pores with an average diameter is 17.5 nm in the shell of these BaMoO4:Pr3+ hollow microspheres, thereby exhibiting a great promise for drug delivery. Meanwhile, the strong, narrow-bandwidth red emission centered at 643 nm from these nanostructures can be efficiently excited from 430 nm to 500 nm. The combination of excellent luminescent properties and a hollow porous nanostructure suggest a great promise in the application of these nanostructures in lighting and displays, and in biomedicine such as targeted drug delivery, integrated imaging, diagnosis, and therapeutics. In addition, the template-free solution synthesis can be applied to the design and fabrication of other functional architectures.

A highly efficient yellow oxyfluoride phosphor Sr2.97−1.5xCaxAl1−2yMgySiyO4F:0.02Ce3+ has been developed as a component of solid state white light emitting diodes (LED). The phosphor emits with a maximum at 545 nm when excited by 430 nm with a quantum efficiency approaching 84%. After substituting magnesium and silicon into the aluminum sites, replacing the strontium by calcium in Sr3AlO4F:Ce3+, we discovered a class of single phase materials. This results in the emission maximum redshift from 460 nm to 545 nm and the excitation red shift from 400 nm to 430 nm (compared with Sr3AlO4F:Ce3+). The combination of an InGaN LED chip (λmax = 430 nm) had a color temperature of about 4500 K and the color rendering index was 78. This phosphor has potential for incorporation into near-UV white LEDs and related applications.

Highly efficient Cr3+- and Yb3+/Nd3+-co-activated YAl3(BO3)4 (YAB) phosphors have been developed as spectral convertors for improving silicon solar cell photovoltaic conversion efficiency. In the YAB lattice, Cr3+ ions act as broadband spectral sensitizers by absorbing UV-Vis (370–750 nm) photons, which are not absorbed by the silicon solar cell. After energy transfer, the Yb3+ acceptors then exhibit strong NIR emission centered at around 1000 nm, which is coupled well with the absorption band of the silicon solar cell. Efficient energy transfer is reflected by a sharp decrease in the excited state lifetime and red photoluminescence (PL) from Cr3+ with increasing Yb3+ concentration. Further evidence in favor of energy transfer is that PL-excitation spectra of NIR luminescence from Yb3+ are identical to those of deep red emission from Cr3+. Trivalent ions Gd3+, Bi3+ and La3+ have been introduced into YAl3(BO3)4:Cr3+,Yb3+ in this study for a stronger NIR PL intensity. Additionally, energy transfer from Cr3+ to Nd3+ is also observed. Yb3+,Nd3+-co-activated YAB shows much broader NIR emission. Due to the effective absorption of Cr3+ in the visible region in YAB and the efficient energy transfer to Yb3+/Nd3+, these materials can be developed as spectral convertors to improve silicon solar cell photovoltaic conversion efficiency.

Three series of BiOMxR1−x (M, R = Cl, Br, I) solid solutions were systematically synthesized through a low-temperature precipitation. These solid solutions were characterized by XRD, FESEM, TEM, EDS, UV-vis spectra, nitrogen sorption/desorption, and PL. The tunable band gaps of the as-prepared solid solutions were realized via only changing the molar ratio of two halide ions. Meanwhile, the influence of citric acid in the formations of controllable morphological structures was discussed to study the growth mechanism of solid solutions. The photocatalytic activities of the bismuth oxyhalide solid solutions have also been investigated by the degradation of Rhodamine-B (RhB) under visible light irradiation. The optimized solid solutions possess higher photocatalytic activity than pure ones [BiOM (M = Cl, Br, I)] due to the broadened range of visible light response and the reduced recombination rate of electron–holes pairs. The results show that the synthesis of BiOMxR1−x (M, R = Cl, Br, I) solid solutions have profound significance for the design of the novel photocatalyst materials.

An efficient red phosphor, BaMoO4:Pr3+, has been fabricated by a convenient solid-state method. A strong red emission centered at 643 nm corresponding to the 3P0→3F2 transition of Pr3+ is observed under 430–500 nm excitation. In addition, improvement of the intensity of the red emission has been achieved by adding an alkali chloride to the BaMoO4:Pr3+ phosphor samples, this being explained by a charge compensation mechanism. The influence of the sintering temperature on the luminescence properties of the phosphors is also discussed.

Cadmium based chalcogenides (CdS, CdSe, CdTe) quantum dots exhibited ultrahigh photoluminescence (PL), quantum yields (QYs) and multicolor luminescence. However, the usual synthesis needs high temperature, inert gas protection, and localized injection operation, which hinder applications seriously. Here, we synthesized CdS QDs and a series of metal-ions-doped QDs using low temperature synthesis (30–80 °C). The synthesis was designed according to supersaturated recrystallization. It was operated under air atmosphere, in DMF solution, free from inert gas protection and used non-injection operation. The obtained QDs exhibit strong and stable luminescence. They have a monodisperse, uniform morphology and good crystallinity. With increasing synthesis temperature, the emission center of the CdS QDs shifts from 500 nm to 550 nm. The metal ions doped in the CdS substrate form a deep level. The emission energy decreases and the emission center shifts to longer wavelengths. The emission peaks located at 520 nm, 534 nm, 540 nm, 578 nm and 625 nm correspond to CdS QDs doped with Sn2+, Sb3+, Ni2+, Mn2+ and Cu2+, respectively. The increased synthesis temperature also results in a red shift of the emission peak. The tunable optical properties and the suitability for large scale production endow the metal-ions-doped CdS QDs with promising potential for lighting and displays, which was demonstrated by white light-emitting diodes with a high CRI value, power efficiency and good stability.

Transition metal sulfides are a kind of potential candidates for efficient and stable CE materials in DSSCs due to their good electrocatalytic ability and stability towards I3− reduction. However, the low conductivity of sulfides is harmful for the electron collection and transfer process, and the absorption/desorption and diffusion process of I−/I3− should be optimized to achieve high electrocatalytic activity over Pt. Herein, a hierarchical CoFeS2/reduced graphene oxide (CoFeS2/rGO) composite was rationally designed and prepared via the in situ conversion of CoFe layer double hydroxide anchored on rGO. Due to the synergistic effects of Co and Fe, unique 3D hierarchical structures formed by nanosheets, and the conductivity of rGO, the CoFeS2/rGO CEs exhibited good electrocatalytic activity and stability towards the reduction of I3− to I−, and the DSSCs could also achieve a high efficiency of 8.82%, higher than those of the devices based on Pt (8.40%) and pure CoFeS2 (8.30%) CEs. Moreover, the devices also showed the characteristics of fast activity onset, good stability, and high multiple start/stop capability. The results indicated that the developed CoFeS2/rGO composite could be a promising alternative for Pt in DSSCs.

Uniform Gd2O2S flower-like nano-assemblies were prepared through one-pot mild solvothermal synthesis. The parallel nanoplates are the building blocks, ∼3 nm in thickness and 20–30 in diameter. Ethanediamine, the main solvent, plays an important role in dissolving a large amount of sulphur and producing active S2− ions, which results in the direct formation of Gd2O2S. Oleylamine, the capping agent, controls the growth of the plate-like structure. Under UV excitation, the Gd2O2S:Eu3+ nano-phosphor shows good red luminescence with a main emission peak at 627 nm. Under 980 nm laser excitation, Gd2O2S:xYb3+,1%Er3+ nano-phosphors exhibit a tuneable emission, shifting from greenish-yellow to orange-yellow, with increasing Yb3+ content.

Trivalent ions B3+, Al3+ and Ga3+ have been introduced into Sr3SiO5:Ce3+ in this study. Among these ions, Al3+ and Ga3+ act as charge compensators and significantly enhance the maximum emission of Ce3+ by about 100% and 90%, respectively. Then, Al3+, Eu2+ co-doped Sr3SiO5:Ce3+ phosphors have been researched, which indicate that the emission spectra can be tuned from 530 to 575 nm by changing the concentration of Eu2+. The CIE chromaticity coordinates of the phosphors were calculated from (0.342, 0.518) to (0.442, 0.479). This indicates a potential for applications in daylight LEDs or warm-white LEDs.