Phosphors in phosphor-converted white light-emitting diodes Recent advances in materials, techniques and properties

Phosphor-converted white light emitting diodes (pc-WLEDs) are emerging as an indispensable solid-state light source for the next generation lighting industry and display systems due to their unique properties including but not limited to energy savings environment-friendliness small volume and long persistence Until now major challenges in pc-WLEDs have been to achieve high luminous efficacy high chromatic stability brilliant color-rending properties and price competitiveness against fluorescent lamps which rely critically on the phosphor properties A comprehensive understanding of the nature and limitations of phosphors and the factors dominating the general trends in pc-WLEDs is of fundamental importance for advancing technological applications This report aims to provide the most recent advances in the synthesis and application of phosphors for pc-WLEDs with emphasis specifically on (a) principles to tune the excitation and emission spectra of phosphors prediction according to crystal field theory and structural chemistry characteristics (e g covalence of chemical bonds electronegativity and polarization effects of element) (b) pc-WLEDs with phosphors excited by blue-LED chips phosphor characteristics structure and activated ions (le Ce3+ and Eu2+) including YAG Ce other garnets non-garnets sulfides and (oxy)nitrides (c) pc-WLEDs with phosphors excited by near ultraviolet LED chips single-phased white-emitting phosphors (e g Eu2+-Mn2+ activated phosphors) red-green-blue phosphors energy transfer and mechanisms involved and (d) new clues for designing novel high-performance phosphors for pc-WLEDs based on available LED chips Emphasis shall also be placed on the relationships among crystal structure luminescence properties and device performances In addition applications challenges and future advances cif pc-WLEDs will be discussed (C) 2010 Elsevier BV All rights reserved