Composites of a reddish-orange-emitting cationic iridium(III) complex doped in silica gel: preparation and application in neutral/warm white light-emitting diodes.

A novel reddish-orange-emitting cationic iridium(III) complex [(PPP) 2 Ir(BPPO)]PF 6 (PPP: 2-(4-pentylphenyl)pyridine; BPPO: 2-(4-(tert -butyl)phenyl)-5-(pyridin-2-yl)-1,3,4-oxadiazole) was synthesized and doped in silica gel via a simple sol-gel method. By comparing photoluminescence (PL) intensity of the composites containing [(PPP) 2 Ir(BPPO)]PF 6 at different doping concentrations, the composite containing 12.5 wt% [(PPP) 2 Ir(BPPO)]PF 6 was determined as the best target product due to its highest PL intensity. This composite showed higher thermal stability and lower thermal quenching property than those of pure [(PPP) 2 Ir(BPPO)]PF 6 , their thermal decomposition temperatures (T d) were 350 °C and 320 °C, their PL intensities at 150 °C were 70.8% and 35.8% of those at 30 °C, respectively. Excited by blue-emitting GaN-based chips, both of pure [(PPP) 2 Ir(BPPO)]PF 6 and the composite can be used as phosphors for fabricating reddish-orange LEDs. Moreover, the cold white light of the LEDs fabricated by blue-emitting GaN-based chips and yellow-emitting Y 3 Al 5 O 12 :Ce3+ (YAG:Ce) can be adjusted into neutral/warm white with good performances when pure [(PPP) 2 Ir(BPPO)]PF 6 or the composite was added in the LEDs as red light sources. Relatively, the LEDs using the composite were much more efficient than the LEDs directly using pure [(PPP) 2 Ir(BPPO)]PF 6 at the same amounts. Cationic iridium(III) complexes being doped into silica gel is an effective way for their application as phosphors in LEDs. [Display omitted] • A novel reddish-orange-emitting cationic iridium(III) complex was synthesized and doped in silica gel. • The complex in silica gel showed higher luminous efficiency, higher thermal stability and lower thermal quenching than the pure complex. • Efficient neutral and warm white light-emitting diodes were fabricated by using the composite and Y 3 Al 5 O 12 :Ce3+ as phosphors. [ABSTRACT FROM AUTHOR]