Inorganic Phosphor Materials for Lighting

Abstract

This chapter addresses the development of inorganic phosphor materials capable of converting the near UV or blue radiation emitted by a light emitting diode to visible radiation that can be suitably combined to yield white light. These materials are at the core of the new generation of solid-state lighting devices that are emerging as a crucial clean and energy saving technology. The chapter introduces the problem of white light generation using inorganic phosphors and the structureproperty relationships in the broad class of phosphor materials, normally containing lanthanide or transition metal ions as dopants. Radiative and non-radiative relaxation mechanisms are briefly described. Phosphors emitting light of different colors (yellow, blue, green, and red) are described and reviewed, classifying them in different chemical families of the host (silicates, phosphates, aluminates, borates, and non-oxide hosts). This research field has grown rapidly and is still growing, but the discovery of new phosphor materials with optimized properties (in terms of emission efficiency, chemical and thermal stability, color, purity, and cost of fabrication) would still be of the utmost importance.

White‐Light‐Emitting Carbon Dots Prepared by the Electrochemical Exfoliation of Graphite

“…An alternate strategy widely employed is to use a phosphor dispersed in a transparent host medium, in combination with a UV‐ or near‐UV‐emitting light‐emitting diode (LED), in which the phosphor has the role of a wavelength converter . Most of the high‐performance white‐light‐emitting devices developed recently use either extremely expensive rare‐earth‐based phosphors (Er, Tb, Sm or Ce as emissive centres) or highly toxic Pd‐/Cd‐based semiconductor quantum dots . Apart from optical excitation to realise white‐light emission, electrically or magnetically driven, or even mechanical‐deformation‐induced, broad‐band emissions have been reported recently …”

“…Although synthetic white light has been successfully generated by using multi‐colour emissive materials, control of the relative intensity ratios of the individual colours is extremely difficult, resulting in low colour quality . Meanwhile, a single phosphor, the emission of which (under single‐wavelength excitation) covers a significant part of the visible spectrum, is conceptually simple and can show many advantages, such as better stability and reproducibility of the chromaticity colour indices (CIE co‐ordinates).…”

Eu(O2C‐C≡C‐CO2): An EuII Containing Anhydrous Coordination Polymer with High Stability and Negative Thermal Expansion

“…It is well‐known that Eu II containing compounds are important phosphors with a large variety of different applications . The broad 4f 6 5d 1 →4f 7 transition is dependent upon the ligand field around Eu II and thus in the focus of many research groups world‐wide . In contrast to those typical findings, no Eu II ‐related luminescence was observed in EuADC, when excited with different energies even at low temperatures (10 K).…”

Photoluminescence Properties of Layered Perovskite-Type Strontium Scandium Oxyfluoride Activated With Mn4+

“…White light emitting diodes (W-LEDs) based on blue-LEDs are widely spreading to various fields as highly efficient solid lightings (Lin et al, 2016; Adachi, 2018; Wang et al, 2018). Artificial white light is basically obtained by combination of blue and yellow light emitted from a blue-LED chip and a yellow-emitting phosphor Y 3 Al 5 O 12 :Ce, respectively.…”