Pr3+-doped oxyfluoride glass ceramic as a white LED color converter wide color gamut

Abstract

Pr3+ singly doped SiO2–Na2O–Al2O3–LaF3 glass ceramics were fabricated as an inorganic color converter with wide color gamut for white light emitting diodes (wLEDs). Under 450 nm LED excitation, the simultaneous photo-luminescence (PL) emissions of green at 502 nm due to the Pr3+:3P1→3H4 transition and red at 613 and 643 nm due to Pr3+:3P0→3H6 and 3P0→3F2, respectively, were observed. Before heat treatment, the PL intensity of the green and red emissions were limited relative to that of the blue electroluminescence (EL), due to the high transparency of the glass. This was highly improved by the crystallization of the glass with heat treatment. PrF3 concentration and heat treatment conditions such as temperature and duration time were varied to adjust the relative intensity of blue (EL), green and red (PL). The formation of LaF3 crystals within the glass ceramic and their effect on the visible spectra are discussed. The glass ceramics were mounted on top of a blue LED to fabricate a wLED, and demonstrate its practical feasibility, with a wide color gamut of up to 120% of the NTSC.