Luminescent Crystals for High-Brightness Laser Based Solid State Lighting
Laser diode (LD) chips do not suffer the “efficiency droop” effects under high-density current driving to the extent that LED chips do, and are therefore considered a promising next-generation solid state lighting source. LD driven light sources combining LD chips and phosphor converters can emit a broad spectrum ranging from UV to IR, making them suitable for applications in many fields including solid-state lighting, medicine, projection displays, smart lighting, future visible light communication, and more. However, under high energy density laser irradiation, conventional powder and glass phosphors with low thermal conductivity display degraded performance due to undesirable thermal quenching behavior. Consequently, there is an urgent need to develop novel crystal phosphors with high efficiency, high thermal stability and especially excellent thermal quenching behavior, high thermal conductivity, long lifetime, and low efficiency droop. It is also important to ensure that LD excited white-light sources have the correct chromatic coordinates located on the blackbody curve, as well as acceptable chromatic index especially low color temperature (Tc). Although yellow-light emitting crystal phosphors such as Ce:YAG have been commercialized, transparent ceramics and single crystals, red-, green-, cyan-, orange-light emitting crystal phosphors, i.e., ceramics/single-crystals/glass-ceramics, are absent but desirable due to their improved thermal quench behavior compared to their powder counterparts. These demands stimulate the need for this special topic, and novel original research including those related to the topics set out below is welcome.
Topics covered include, but are not limited to:
- Exploration of novel phosphors with wide emitting wavelength, excellent thermal quench behavior, high efficiency, high thermal conductivity, and which are suitable for sintering to be transparent ceramics, or glass ceramics, or bulk single crystals
- Exploration of highly efficient crystal phosphors with high thermal stability and which can emit red, cyan, orange, green light
- Surface patterning technology of crystal phosphors to improve extraction efficiency of the output light to avoid edge waveguide effects
- Modulation of chromatic index, chromatic coordinates, wavelengths, and/or Tc in LD excited white light sources
Guest Editors
Yongge Cao, Songshan Lake Materials Laboratory
Xueyuan Chen, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences
Quanlin Liu, University of Science and Technology Beijing
Rongjun Xie, Xiamen University