An oil/water interfacial self-assembly strategy was successfully used to purify hydrophilic carbon dots (CDs) synthesized by a typical hydrothermal method. Subsequently, organophilic octadecylamine (ODA)-capped carbon dots were obtained by further surface modification. Finally, transparent fluorescent bulk materials were fabricated through the above processes derived from hydrophilic carbon dots.

•The direct band gap of CaZnOS is calculated to be 2.4 eV using the CASTEP mode.•CaZnOS:Ce3+ exhibits a broad band emission in the wavelength range of 450–650 nm.•The mechanism of luminescence and concentration quenching of Ce3+ have been investigated in detail.The electronic structure of CaZnOS calculated using the CASTEP mode is an intermediate band gap semiconductor with a direct band gap of 2.4 eV. Ce3+-activated CaZnOS samples were prepared by a solid-state reaction method at high temperature and their luminescence properties under UV–visible and X-ray excitation were investigated. CaZnOS:Ce3+ exhibits a broad band emission in the wavelength range of 450–650 nm, originating from the 5d–4f transition of Ce3+ for both under blue light (460 nm) and X-ray excitation. The mechanism of luminescence and concentration quenching of Ce3+ in CaZnOS have been investigated in detail. The results showed that the relative luminescence intensity reaches a maximum at 1 mol% of Ce3+, and the electric dipole–dipole interaction is the major mechanism for concentration quenching of Ce3+ emission in CaZnOS. The potential application of CaZnOS:Ce3+ has been pointed out.

This study fully investigated the vacuum ultraviolet excitation spectra of pure and rare-earth (RE=Eu, Tb and Dy)-doped A2Zr(PO4)2 (A=Li, Na and K) phosphors. The synthesized Na and Li compounds were characterized by XRD showing two new types of phases after indexation. Although these three pure compounds had different crystal structures, they exhibited similar luminescence properties. For Eu3+-activated samples, the broad excitation band centered at 217 nm could be attributed to the CT transition between O2– (2p6) and Eu3+ ions. For Tb3+-doped samples, two groups of f-d transitions were observed, where a strong broad band at 221 nm was due to the spin-allowed f-d transition. Energy transfer from O2– to Dy3+ was not observed in Dy3+-doped phosphors, probably because it overlapped considerably with the CT transition from O2– to Zr4+ at 187 nm.The VUV excitation and emission spectra of un-doped A2Zr(PO4)2 (A=Li, Na and K), and the possible luminescence-active center, the octahedral Zr(PO4)6 moieties in the structure

The electronic structure of SrAlSi4N7 was calculated using the CASTEP code and SrAlSi4N7 is an intermediate band gap semiconductor with an indirect energy gap of 3.6 eV. Ce3+ and Yb2+-activated SrAlSi4N7 samples were prepared by a solid-state reaction method at high temperature, and their photoluminescence properties were investigated. SrAlSi4N7:Ce3+ shows a broad band emission in the wavelength range of 450–700 nm, originating from the 5d1–4f1 transition of Ce3+. The emission band of Ce3+ shifts to longer wavelength with an increase of Ce3+ concentration due to the increased Stokes shift and reabsorption by Ce3+. SrAlSi4N7:Yb2+ can be excited efficiently over a broad spectral range between 300 and 550 nm, and exhibits a single intense red emission at 600 nm with a full width at half maximum of 95 nm due to the electronic transitions from the excited state of 4f135d to the ground state 4f14 of Yb2+. The low energy of Yb2+ emission in SrAlSi4N7 can be attributed to the large nephelauxetic effect and crystal field splitting due to the coordination of Yb2+ by nitrogen. In addition, Sr1−2xCexLixAlSi4N7 shows higher thermal stability in air than that of Sr1−yYbyAlSi4N7 (0 ≤ x, y ≤ 0.1). A white-light LED can be generated by using single SrAlSi4N7:Ce3+ as the wavelength conversion phosphor combined with a blue LED chip (InGaN). The obtained LED exhibits a luminous efficiency of 74.3 lm W−1 at a corrected color temperature (CCT) up to 6350 K, and the color rendering index (CRI Ra) is around 78. These novel developed yellow-red phosphors have potential applications in spectral conversion materials for white-LEDs.

Single crystals of Ba3BP3O12 with size of 10×8×2 mm3 have been grown by the top-seeded solution growth (TSSG) method using BPO4–NaF mixture as the flux. The crystals were characterized by X-ray powder diffraction, field emission scanning electron microscopy (FE-SEM) and transmittance spectrum. Ba3BP3O12 single crystal exhibits wide transparency in the range 250–800 nm. The preparation process of starting materials and the effect of flux on the crystal growth were discussed.

The electronic structure of SrAlSi4N7 was calculated using the CASTEP code and SrAlSi4N7 is an intermediate band gap semiconductor with an indirect energy gap of 3.6 eV. Ce3+ and Yb2+-activated SrAlSi4N7 samples were prepared by a solid-state reaction method at high temperature, and their photoluminescence properties were investigated. SrAlSi4N7:Ce3+ shows a broad band emission in the wavelength range of 450–700 nm, originating from the 5d1–4f1 transition of Ce3+. The emission band of Ce3+ shifts to longer wavelength with an increase of Ce3+ concentration due to the increased Stokes shift and reabsorption by Ce3+. SrAlSi4N7:Yb2+ can be excited efficiently over a broad spectral range between 300 and 550 nm, and exhibits a single intense red emission at 600 nm with a full width at half maximum of 95 nm due to the electronic transitions from the excited state of 4f135d to the ground state 4f14 of Yb2+. The low energy of Yb2+ emission in SrAlSi4N7 can be attributed to the large nephelauxetic effect and crystal field splitting due to the coordination of Yb2+ by nitrogen. In addition, Sr1−2xCexLixAlSi4N7 shows higher thermal stability in air than that of Sr1−yYbyAlSi4N7 (0 ≤ x, y ≤ 0.1). A white-light LED can be generated by using single SrAlSi4N7:Ce3+ as the wavelength conversion phosphor combined with a blue LED chip (InGaN). The obtained LED exhibits a luminous efficiency of 74.3 lm W−1 at a corrected color temperature (CCT) up to 6350 K, and the color rendering index (CRI Ra) is around 78. These novel developed yellow-red phosphors have potential applications in spectral conversion materials for white-LEDs.