Tuning optical properties of CsPbBr3 by mixing Nd3+trivalent lanthanide halide cations for blue light emitting devices.

In recent years, significant progress has been made in the red and green perovskite quantum dots (PQDs) based light-emitting devices. However, a scarcity of blue-emitting devices that are extremely efficient precludes their research and development for optoelectronic applications. Taking advantage of tunable bandgaps of PQDs over the entire visible spectrum, herein we tune optical properties of CSPbBr3 by mixing Nd3+ trivalent lanthanide halide cations for blue light-emitting devices. The CsPbBr3 PQDs doped with Nd3+ trivalent lanthanide halide cations emitted strong photoemission from green into the blue region. By adjusting their doping concentration, a tunable wavelength from (515 nm) to (450 nm) was achieved with FWHM from (37.83 nm) to (16.6 nm). We simultaneously observed PL linewidth broadening thermal quenching of PL and the blue shift of the optical bandgap from temperature-dependent PL studies. The Nd3+ cations into CsPbBr3 PQDs more efficiently reduced non-radiative recombination. As a result of the efficient removal of defects from PQDs, the photoluminescence quantum yield (PLQY) has been significantly increased to 91% in the blue-emitting region. Significantly, Nd3+ PQDs exhibit excellent long-term stability against the external environment, including water, temperature, and ultraviolet light irradiation. Moreover, we successfully transformed Nd3+ doped PQDs into highly fluorescent nanocomposites. Incorporating these findings, we fabricate and test a stable blue light-emitting LED with EL emission at (462 nm), (475 nm), and successfully produce white light emission from Nd3+ doped nanocomposites with a CIE at (0.32, 0.34), respectively. The findings imply that low-cost Nd3+ doped perovskites may be attractive as light converters in LCDs with a broad color gamut.

Temperature behavior of X-Ray luminescence spectra of ZnSe

In the given paper, the temperature dependences ([Formula: see text]–300 K) of the green band intensity at wavelengths [Formula: see text] nm and [Formula: see text] nm have been measured and observed, respectively, from the polished and unpolished surface (PS and unPS) of a polycrystalline CVD (chemical vapor deposition) ZnSe sample upon excitation by X-ray quanta ([Formula: see text]. In both cases, the activation energy of thermal quenching has been determined, and the reasons for thermal quenching have been considered in detail. Along with XRL spectra analysis, the temperature behavior of the green band observed upon excitation by an ultraviolet (UV) laser (He–Cd, [Formula: see text] nm) from the PS and unPS in the temperature range [Formula: see text]–200 K has been discussed in more detail.

Multiple ratiometric nanothermometry using semiconductor BiFeO3 nanowires and quantitative validation of thermal sensitivity

Here, we report a very sensitive, non-contact, ratio-metric, and robust luminescence-based temperature sensing using a combination of conventional photoluminescence (PL) and negative thermal quenching (NTQ) mechanisms of semiconductor BiFeO3 (BFO) nanowires. Using this approach, we have demonstrated the absolute thermal sensitivity of ~ 10 mK−1 over the 300–438 K temperature range and the relative sensitivity of 0.75% K−1 at 300 K. Further, we have validated thermal sensitivity of BFO nanowires quantitatively using linear regression and analytical hierarchy process (AHP) and found close match with the experimental results. These results indicated that BFO nanowires are excellent candidates for developing high‐performance luminescence-based temperature sensors. Graphical abstract

YAG : R3+ (R = Ce, Dy, Yb) nanophosphor-based luminescent fibre-optic sensors for temperature measurements in the range 20–500 °C

We report the development of a group of luminescent fibre-optic temperature sensors that use Ce3+-, Dy3+-, and Yb3+-doped yttrium aluminium garnet (YAG) nanophosphors as thermosensitive materials. The nanophosphors have been prepared in the form of powders with a crystallite size from 19 to 27 nm by a polymer ? salt method and exhibit bright luminescence at 550 (YAG : Ce3+), 400, 480 (YAG : Dy3+), and 1030 nm (YAG : Yb3+). The sensor design includes a silica capillary, partially filled with a nanophosphor, and two large-aperture multimode optical fibres located in the capillary, which deliver excitation light and receive and transmit the photoluminescence signal. The photoluminescence signal amplitude of all the sensors decreases exponentially with increasing temperature, pointing to characteristic thermal quenching of photoluminescence and adequate operation of the devices up to 500 °C. The highest temperature sensitivity among the fibre-optic sensors is offered by the YAG : Ce3+ nanophosphor-based devices.

Люминофоры холодного голубого излучения на основе оксида алюминия, допированного диспрозием

Al2О3:Dy3+ oxides with different colors luminescence were synthesized using precursor technology. The phase composition and crystal structure of the obtained materials were established by X-ray powder diffraction analysis. The excitation and emission spectra, decay curves, thermal quenching of luminescence were studied. Under UV excitation, the phosphors exhibit blue, purplish blue, white emission depending on the concentration of dysprosium and the temperature of annealing of the Al1-xDyx(OH)(HCOO)2 precursor in air.