Effects of TiO2-doped silicone encapsulation material on the light extraction efficiency of GaN-based blue light-emitting diodes

• Silicone encapsulation of high-power light-emitting diodes (LEDs) was tested.
• TiO2-doped silicone encapsulated LEDs showed enhanced light extraction efficiency.
• Enhanced temperature stability and reliability were achieved.

The effects of silicone encapsulation material doped with TiO2 nanoparticles (NPs) on the light extraction efficiency (LEE) of GaN-based blue light-emitting diodes (LEDs) were investigated. The LED samples were encapsulated with pure silicone, uniform TiO2 NP-doped silicone, TiO2 NP-doped silicone around the chip only, and TiO2 NP-doped silicone encapsulation dome. The average refractive index of silicone was increased by doping with TiO2 NPs with an average diameter of 21 nm, and the LEE of GaN-based blue LEDs was also enhanced. Methyl and phenyl silicone were used as encapsulation materials. TiO2 NP-doped methyl silicone encapsulation dome increased the LEE by 10.9%, whereas TiO2 NP-doped phenyl silicone encapsulation dome increased the LEE by 12.9%. The thermal effect, reliability test, and LEE of the LEDs were also analyzed. TiO2 NP-doped silicone encapsulation materials could better enhance LEE compared with pure silicone encapsulation material because of the increased average refractive index, which reduced the total internal reflection at the encapsulation at the air interface.