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Graphite like C3N4 (g-C3N4) was synthesized facilely via the low temperature thermal condensation of melamine between 300–650°C. The results showed that the products maintained as melamine when the temperature is below 300°C. With the increase of temperature, the products were transformed into carbon nitride and amorphous g-C3N4 successively. The morphology of products was changed from spherical nanoparticles of melamine into layer carbon nitride and g-C3N4 with the increase of temperature. The photoluminescence spectra showed that the carbon nitride products have continuous tunable photoluminescence properties in the visible region with increasing temperature. With the help of steady state, transient state time-resolved photoluminescence spectra and Raman microstructural characterization, a novel tunable photoluminescence mechanism was founded systematically, which is mainly related to the two dimensional π-conjugated polymeric network and the lone pair of the carbon nitride.

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The high-precision patterning of metal halide perovskites (MHPs) is of paramount importance for their device application. Here, we demonstrate the femtosecond (fs)-laserassisted formation of three-dimensional MHP nanocrystal (NC) patterns with strong blue photoluminescence (PL) inside an oxide glass. Our strategy enables the crystallization and erasing of CsPb(Cl/Br) 3 NCs inside a glass localized around the laser focal area through a combination of fs laser irradiation and thermal treatment processes. These recoverable patterns exhibit a switchable PL associated with the laser-induced defect and the thermal healing of MHP NCs that are benefits from the soft ionic crystal structure and low formation energy of the MHPs. Due to the high stability offered by the protection of the oxide glass matrix, the laser printing of fine-structured MHP micropatterns can be repeated over multiple cycles with a high robustness compared with their colloidal process counterparts. Our results demonstrate a simple strategy for creating emissive patterns inside a stable and transparent solid matrix that could be promising for applications including information storage, three-dimensional displays, anticounterfeit labels, and information security protection.

For phosphor-converted white LEDs based on UV chips, it is essential to search high efficient phosphors that better feature with broadly tunable emission and particularly have no or less excitation in visible ranges.

In this article, we propose a facile method for synthesis of K 2 SiF 6 :Mn 4+ phosphor and discuss its promising application in warm-white light emitting diodes (LED

We present a series of efficient near-infrared (NIR) Cr 3+ -doped non-gallate long-persistence phosphors (Zn 2 SnO 4 : Cr and Zn (2-x) Al 2x Sn (1-x) O 4 : Cr) and highlight their special optical characteristics of broad emission band (650-1200 nm, peaking at 800 nm) and long afterglow duration (435 h). In the context of materials selection, these systems successfully avoid the existing ubiquitous reliance on gallates as hosts in Cr 3+ -doped phosphorescent phosphors. Zn 2 SnO 4 is employed as a host to take advantage of its characteristic inverse spinel crystal structure, easy substitution into Zn 2+ and Sn 4+ sites by Cr 3+ in distorted octahedral coordination and non-equivalent substitution. In this work, Al dopant was introduced both to precisely tailor the local crystal field around the activator center, Cr 3+ , and to redeploy trap distribution in the system. Indeed, such redeployment permits band gap adjustment and the dynamic variation of the annihilation and the formation of defects. The results demonstrate that the method employed here can be an effective way to fabricate multi-wavelength, low-cost, NIR phosphorescent phosphors with many potential multifunctional bio-imaging applications.