Development of optical-thermal coupled model for phosphor-converted LEDs

In this review, first, we discussed the effect of phosphor features on optical properties by the software simulation in detail. A combination of these parameters: phosphor material, phosphor particle size and particle distribution, phosphor layer concentration, phosphor layer thickness, geometry, and location of the phosphor layer, will result in the final optical performance of the phosphor layer. Secondly, we introduced how to improve light extraction efficiency with various proposed methods. Thirdly, we summarized the thermal models to predict the phosphor temperature and the junction temperature. To stabilize the optical performance of phosphor-converted light emitting diodes (PC-LEDs), much effort has been made to reduce the junction temperature of the LED chips. The phosphor temperature, a critical reliability concern for PC-LEDs, should be attracted academic interest. Finally, we summed up optical-thermal coupled model for phosphors and summarized future optical- thermal issues exploring the light quality for LEDs. We foresee that optical-thermal coupled model for PC-LEDs should be paid more attention in the future.

Seeking new,ultra-narrow-band blue emitting phosphors with high color purity for wide color gamut displays

Ultra-narrow-band phosphors have gained widespread applications in lighting and displays to enhance brightness and improve color saturation.Typical phosphor designs employ UCr_(4)C_(4)-type compounds and designing new narrow-band phosphors with high color purity is a major challenge.Here,we explored a Eu^(2+)-doped Ba_(5)GeO_(4)Br_(6)phosphor,showing a narrow-band blue emission(λ_(em)=436 nm) excitation at the near-ultraviolet light with a full width at half maximum of 30.7 nm and high color purity of 96.6%.In addition,attractive cathodoluminescence characteristics were systematically analyzed by varying filament current(30-70 mA) and accelerating voltage(3-7 eV).Robust anti-degradation behavior and color point stability under continuous electron beam bombardment were confirmed.Given its excellent performance in photoluminescence and cathodoluminescence,application in wide color gamut displays appears promising.Using commercial phosphors β-SiAlON:Eu^(2+)and K_(2)SiF6:Mn^(4+)as green and red light co nverte rs respectively,and the title phosphor as the blue light converters,the fabricated w-LED exhibits a wide color gamut of 82% NTSC.