The reduction of the thermal quenching effect in laser-excited phosphor converters using highly thermally conductive hBN particles

Abstract

Phosphor converters for solid state lighting applications experience a strong thermal stress under high-excitation power densities. The recent interest in laser diode based lighting has made this issue even more severe. This research presents an effective approach to reduce the thermal quenching effect and damage of laser-excited phosphor-silicone converters using thermally conductive hexagonal boron nitride (hBN) particles. Herein, the samples are analyzed by employing phosphor thermometry based on the photoluminescence decay time, and thermo-imaging techniques. The study shows that hBN particle incorporation increases the thermal conductivity of a phosphor-silicone mixture up to 5 times. It turns out, that the addition of hBN to the Eu$$^{2+}$$ 2 + doped chalcogenide-silicone converters can increase the top-limit excitation power density from 60 to 180 W cm$$^{-2}$$ - 2 , thus reaching a 2.5 times higher output. Moreover, it is shown that the presence of hBN in Ce$$^{3+}$$ 3 + activated garnet phosphor converters, may increase the output power by up to 1.8 times and that such converters can withstand 218 W cm$$^{-2}$$ - 2 excitation. Besides, hBN particles are also found to enhance the stability of the converters chromaticity and luminous efficacy of radiation. This means that the addition of hBN particles into silicone-based phosphor converter media is applicable in a wide range of different areas, in particular, the ones requiring a high optical power output density.

Biphasic (Lu,Gd) 3Al 5O 12-based transparent nanoceramic color converters for high-power white LED/LD lighting

“…With the characteristics of high luminous efficiency, excellent color quality, and good designability, white light-emitting diodes (WLEDs) based on blue LED chips are the most successful light-emitting structure in practical application [8][9][10]. In recent years, due to that laser diodes (LDs) can maintain high luminous efficiency at high power, lighting devices with LDs as the excitation source have aroused great interest of researchers [11][12][13][14][15]. With the development of modern lighting technology, higher requirements are also put forward for the performance of color conversion materials.…”

Realizing High‐Power Laser Lighting: Artfully Importing Micrometer BN into Ce: GdYAG Phosphor‐in‐Glass Film

“…In addition, there are many studies have indicated that thermal performances and optical properties of materials under laser irradiation can be upgraded by adding a high TC medium. [ 28–30 ] In recent years, Al 2 O 3 –YAG: Ce, [ 31–37 ] hBN–YAG: Ce, [ 38 ] MgAl 2 O 4 –YAG: Ce, [ 39 ] AlN–YAG: Ce [ 40,41 ] have been systematically investigated by many researchers. Here, we attempt to add micrometer BN which possesses the merits of environmentally friendly, low cost and ultrahigh TC (33 W m −1 K −1 ) into Ce: GdYAG PiG films as light scattering center to increase heat dissipation and porosity, further improving the optical and thermal performances under blue laser irradiation.…”

Luminous Performances Characterization of YAG: Ce3+ Phosphor/Silicone Composites Using Both Reflective and Transmissive Laser Excitations

“…Only a few literatures are focused on improving the thermal stability of laser-excited phosphor/silicone composite. For example, Akvilė et al [28] prepared a laser-excited phosphor/silicone composite with high thermal conductivity (~0.95W/m•K) by adding hexagonal boron nitride. To dissipate the heat accumulating in the surface, Ding et al [29] proposed a converter with porous copper framework/paraffin embedded into the phosphor/silicone composite.…”