Spectroscopic properties of high-temperature sintered SrS:0.05%Ce3+ under high hydrostatic pressure

In this study, we present spectroscopic properties of high-temperature sintered SrS:0.05%Ce³⁺ under high hydrostatic pressure.

Metal Quinolates as Phosphors for PC-LED Applications

Metal quinolates, Liq Alq₃ Znq₂ Mgq₂ exhibit efficient luminescence in blue green region and find applications as emission layer in OLEDs. In most of these quinolates the excitation spectra are broad in the range 350 to 410 nm, just short of emission spectra of efficient GaN based blue LEDs. In this paper we report metal quinolates synthesized by slightly modified method in which the excitation gets extended beyond 450 nm so that there is better overlap between emission spectra of blue LED and the excitation spectra. Therefore these phosphors may be used for PC-LED applications.

An intense elastico-mechanoluminescence material CaZnOS:Mn2+ for sensing and imaging multiple mechanical stresses

The elastico-mechanoluminescence (EML) properties of CaZnOS:Mn2+ are investigated. The CaZnOS:Mn2+/epoxy resin composite can simultaneously "feel" (sense) and "see" (image) various types of mechanical stress over a wide energy and frequency range (ultrasonic vibration, impact, friction and compression) as an intense red emission (610 nm) from Mn2+ ions. Further, the accurate linear relation between emission intensity and different stress parameters (intensity, energy and deformation rate) are confirmed. The EML mechanism is explained using a piezoelectrically induced trapped carrier excitation mode. All the results imply that CaZnOS:Mn2+ has potential as a stress probe to sense and image multiple mechanical stresses and decipher the stress intensity distribution.

Novel yellowish-orange Sr8Al12O24S2:Eu2+ phosphor for application in blue light-emitting diode based white LED

A new yellowish-orange phosphor, Sr(8)Al(12)O(24)S(2):Eu(2+), was synthesized by the solid-state method and its photoluminescence properties were investigated by excitation and emission spectra. Its excitation band is extending from 400-500 nm, which is adaptable to the emission band of blue LED chips (450-470 nm). Upon the excitation of 450 nm light, the phosphor exhibits strong yellowish-orange emission centered at 605 nm with good thermal stability. A white light-emitting diode (W-LED) that consists of a blue LED chip (approximately 470 nm) and a (Sr(0.92)Eu(0.08))(8)Al(12)O(24)S(2) phosphor is demonstrated. The CIE1931 chromaticity coordinates (x, y) are (0.34, 0.25), the correlated color temperature (CCT) is 4300 K, and the luminous efficacy of this W-LED is 14.2 lm/W at room temperature and with a forward-bias current of 400 mA.

High color rendering white light-emitting-diode illuminator using the red-emitting Eu(2+)-activated CaZnOS phosphors excited by blue LED

A red phosphor CaZnOS:Eu(2+) was synthesized by solid state reaction and has been evaluated as a candidate for white LEDs. For this material, the XRD, PL, PL excitation (PLE) and diffuse reflection spectra have also been investigated. CaZnOS:Eu(2+) reveals a broad absorption band and good color purity. By utilizing a mixture of red-emitting CaZnOS:Eu(2+), green-emitting (Ba,Sr)(2)SiO(4):Eu(2+) and yellow-emitting Y(3)Al(5)O(12):Ce(3+) as light converters, an intense white InGaN-based blue-LED (~460 nm) was fabricated to exhibit a high color-rendering index Ra of 85 at a correlated color temperature of 4870 K. Based on the results, we are currently evaluating the potential application of CaZnOS:Eu(2+) as a red-emitting blue-chip convertible phosphor.