Experimental demonstration of energy-transfer ratchet intermediate-band solar cell

A detailed balance calculation reveals an extremely high efficiency of 63.2% for intermediate-band solar cells (IBSCs) under maximum sunlight concentration. However, an actual IBSC device with an efficiency larger than the Shockley-Queisser (SQ) limit has so far not been reported. The main difficulties lie in realizing an efficient sequential two-photon absorption (STPA) which requires a sufficiently long lifetime intermediate state or intermediate band. In this article, we propose the concept of a ratchet type IBSC, utilizing a long lifetime of rare-earth ion luminescence centers in Erbium-doped GaAs. The temperature dependent differential external quantum efficiency reveals a significant STPA contribution originating from the Er3+ luminescence center. All the results were modeled and interpreted by integrating the ratchet effect with up-conversion along with a density functional theory (DFT) simulation. Our work demonstrates that the long lifetime energy-transfer mechanism in Er3+ centers contributes directly to the formation of a ratchet type IB.

With single luminescence center ultra-broadband near-infrared LiScGeO4:Cr phosphor for biological tissue penetration

In this work, in order to meet the application of near-infrared phosphor-converted light emitting diodes (pc-LEDs), an ultra-broadband emission phosphor LiScGeO4:Cr phosphor was synthesized, and its FWHM reached 335 nm,...

Highly Stable Mn4+-Activated Red-Emitting Fluoride Phosphors and Enhanced moisture stability for White LEDs

As a highly productive narrow-band emission red phosphor, K2SiF6:Mn4+ has towardly application market in pc-WLEDs (Phosphor-converted white light-emitting diodes) and LCD (Liquid crystal display). However, the poor moisture resistance property is recognized impediment for generalizing its wider commercialization. Herein, we adopt a simply green and convenient strategy based on Fe2+, which is committed to decreasing the reaction between luminescence center and water. The K2SiF6:Mn4+ as expected exhibits highly efficient red emission upon excitation.

Effects of Fe2+ on Moisture Resistance of Fluoride Red Phosphors

Nowadays, K2SiF6:Mn4+ has been made extensive use of in technologies available, applied to LCD (Liquid crystal display) and pc-WLEDs (Phosphor-converted white light-emitting diodes). Nevertheless, there are still some significant problems needing solved, one of which is the poor moisture resistance. To expand its application in optical devices, this paper proposes a green and simple strategy on the basis of Fe2+, which effectively achieves a reduction of the reaction between water and luminescence center.

Optical properties of SrF2 and SrF2:Ce3+ crystals codoped with In3+

In3+ states are located close to electron traps and have a band character, the transfer of electrons from conduction band to the luminescence center is possible without significant trapping which facilitates fast luminescence in SrF2:Ce3+,In3+.

INFLUENCE OF PLASTIC DEFORMATION ON THE PHYSICAL PROPERTIES OF GRANULAR QUARTZ

Purpose. To study traces of plastic deformation in quartz of crystalline rocks of the Sea of Azov. Methodology. Work was done in the field to observe the crystallinity of the crystalline rocks of the Sea of ​​Azov. In laboratory conditions, samples were made from samples taken of rocks and quartz, in which traces of plastic deformation were observed qualitatively by visual and optical methods by transmission and reflection. In natural and ultraviolet light, the physical properties of quartz were quantified, and the effects of luminescence in quartz samples and quartz sandstone material were studied and analyzed. Results. The forms of manifestation of quartzity in crystalline rocks of the Azov Sea were studied, geological bodies composed of quartz were tested, samples were taken from samples taken to observe traces of plastic deformation. The fact of luminescence of granular quartz was established, in which traces of plastic deformation act as luminescence centers. The luminescence of Donbass Carboniferous sandstones is shown, in which quartz grains, which bear traces of plastic deformations, serve as luminescence centers. Scientific novelty. A scientific fact has been established that traces of plastic deformation serve as centers of luminescence of quartz. Practical significance. The established effect of the relationship between quartz luminescence and traces of plastic deformation can be used in the field as a diagnostic sign of plastic deformation of quartz and in mine ones for qualitative control of the impact hazard of Donbass sandstones. Keywords: quartz content, granular quartz, luminescence, luminescence center, traces of plastic deformation, impact hazard of sandstones.