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.

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.

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.

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.

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.

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.

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.

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.

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.