Feeble white emission with a low Colour Rendering Index (CRI) has become the principal gridlock for the extensive commercialization of phosphor converted white LEDs (pc-WLEDs). Fusion of red, green and blue emitting rare-earth (RE) ions in a suitable host can overcome these drawbacks but the energy migration between multiple RE ions at single excitation wavelength defines the key standpoint in designing such white light emitting phosphors. Apart from the abovementioned obstacles, recently traditional optical temperature sensors based on RE ions have faced difficulties due to their low relative sensitivity and large detection error. Keeping these points in mind, in this work, a series of MgAl2O4:Dy3+,Eu3+ nanophosphors are synthesized among which 2% Dy3+,0.2% Eu3+ doped MgAl2O4 nanophosphors demonstrate strong white emission with CIE co-ordinates of (0.31, 0.33), and high quantum yield (∼67%), which could be directly utilized for pc-WLED based solid state lighting devices. Detailed investigation of PL properties reveals that Eu3+ ions can be well sensitized by Dy3+ under near-ultraviolet excitation of 351 nm. Dexter's theory & Reisfeld's approximation are employed for an in-depth analysis of the inter-RE energy transfer (ET) mechanism, which signposts that the dipole-quadrupole interaction phenomenon is responsible for the ET process from Dy3+ to Eu3+. Additionally, the validated ET plays a pivotal role in demonstrating the self-referencing ratiometric temperature sensor behaviour supported by a distinct high temperature thermal quenching trend between Dy3+ and Eu3+ ions. Hence the obtained nanophosphors are highly promising for utilizing in WLED based solid state lighting and self-referencing ratiometric temperature sensor applications.

In recent years, rare-earth-doped nanophosphors have attracted great attention in the field of luminescent materials for advanced solid-state lighting and high-resolution display applications. However, the low efficiency of concurrent red phosphors creates a major bottleneck for easy commercialization of these devices. In this work, intense red-light-emitting K + -codoped BaAl 2 O 4 :Eu 3+ nanophosphors having an average crystallite size of 54 nm were synthesized via a modified sol–gel method. The derived nanophosphors exhibit strong red emission produced by the 5 D 0 → 7 F J ( J = 0, 1, 2, 3, 4) transitions of Eu 3+ upon UV and low-voltage electron beam excitation. Comparative photoluminescence (PL) analysis is executed for Eu 3+ -activated and K + -coactivated BaAl 2 O 4 :Eu 3+ nanophosphors, demonstrating remarkable enhancement in PL intensity as well as thermal stability due to K + codoping. The origin of this PL enhancement is also analyzed from first-principles calculations using density functional theory. Achievement of charge compensation with the addition of a K + coactivator plays an important role in increasing the radiative lifetime and color purity of the codoped nanophosphors. Obtained results substantially approve the promising prospects of this nanophosphor in the promptly growing field of solid-state lighting and field emission display devices.

Spherical Eu3+:Y4Al2O9 nanophosphors exhibit brilliant PL behavior with enhanced color purity and excited state lifetime.

A melamine-based crystalline organic polymer as a highly efficient ultra-trace Hg2+ ion sensor with a detection limit of 0.03 ppb.

The first thermoelectric (TE) properties of simple polyol method-synthesized Cu 1−x Bi x S (x = 0, 0.02, 0.04, 0.06) nanosheets are reported here. Various characterizations like Rietveld-refined X-ray diffraction (XRD), Raman spectroscopy, Xray photoelectron spectroscopy (XPS), and energy-dispersive X-ray (EDAX) data analysis confirm their single-phase nature of hexagonal crystal structure with space group P63/mmc, stoichiometric nature, valence states of the elements, and nominal elemental composition. Field emission scanning electron microscopy (FESEM) images show nanosheets (NSs) with an average thickness of 27 nm. The doping of Bi atoms in the CuS lattice has been evident from the systematic increase in its crystallite size, optical band gaps, photoluminescence peak intensities, Seebeck coefficients, resistivity, thermoelectric power factors (PFs), and thermoelectric figure of merits (ZTs) with increasing x. The selected area electron diffraction (SAED) pattern confirms that nanosheets are single crystalline in nature. Fourier transform infrared (FTIR) data confirms the absorption bands of the sulfides. The value of the Seebeck coefficient increases with increasing x without deteriorating the electrical conductivity too much due to the energy-dependent scattering of the carriers at the interfaces and the modulation doping. An enhancement of 231% in the thermoelectric power factor and a 6-fold increase in ZT, both at 300 K for x = 0.06 compared to x = 0, are found that show interesting outcomes for these toxic-and rare-earth element-free TE materials.