One-step synthesis and double emission (Ca1+ x − y Eu y )Ga2S4+ x phosphor for white LEDs

Abstract: (Ca1+ x − y Eu y )Ga2S4+ x phosphors have been synthesized one step by solid state reaction. The photoluminescence excitation and emission spectra of phosphors have been studied; the influence of host composition and Eu2+ concentration on emission spectra has also been investigated. The emission spectrum consists of yellow emission at 550 nm and red emission at 650 nm. It also indicates that the excitation spectrum is a broadband and can be well matched with the emission of GaN chip. Combined these phosphors with 460 nm-emitting GaN chips, White LEDs have been fabricated. Their electroluminescence spectra have been measured under 20 mA forward-bias current. Their CIE chromaticity coordinates and color temperature indicate that (Ca1+ x − y Eu y )Ga2S4+ x phosphors are promising phosphors for GaN-based white LEDs. [Copyright &y& Elsevier]