Thermally stable lead-free phosphor in glass enhancement performance of light emitting diodes application.

Abstract

A co-sintering method for preparing PIG is proposed, a Ce3+ doped yttrium aluminum garnet (YAG:Ce) phosphor in glass (PIG) slice is fabricated through co-sintering polycrystalline Ce:YAG phosphor, and a new, to the best of our knowledge, homemade matrix glass SiO2-K2O-BaO-B2O3 glass powder is detected to confirm crystal phase by X-ray powder diffractions (XRD) and micromorphology by scanning electron microscope (SEM). The YAG:Ce phosphor particles dispersed in the matrix are vividly observed and their distributions are relatively uniform. The PIG packaged light-emitting diode (LED) sample shows a relatively lower correlated color temperature (CCT) than the conventional phosphor-dispensing LED sample. White light can be achieved in the PIG slice under 465nm LED excitation by controlling the phosphor concentration or thickness. The highest luminous efficacy of the PIG slice packaged white LED is 94.67lm/W at 100mA. Controllable geometrical and optical properties of the YAG:Ce PIG can generate evident improvements in the manufacturing of identical CCTs for high-power white LEDs. The combination of PIG with a blue LED chip of a specific wavelength, if measured before final assembly, enables targeted production of specific CCT white LEDs. PIG technology allows the realization of high stability and thermal conductivity for the phosphor layer. This simple method provides many possibilities for LED packaging, including thin film flip chip and remote phosphor technology.