Hue dual-chromatic calcium chlorosilicate phosphor for light-emitting diode having yellow and white illumination

Abstract

High-thermal solid phase reactions produced a series of bright green-yellow phosphors called Ca₃SiO₄Cl₂,Eu²⁺,Mn²⁺ (CaM). For example, powder dispersed reflection, photoluminescence excitation (PE), and along with emission spectra, were used to determine their luminous characteristics at between 10 K and 450 K of temperature. While the CaM exhibits wide absorption bands in the 250-450 nm range, which matches the near-uv of the InGaN-based chips, they also display two dominant absorptions, attributed to the 5d → 4f Eu²⁺ transformation, as well as the ⁴T_1g(⁴G) → ⁶A_1g(⁶S) transfer of the two ions Eu²⁺ and Mn²⁺, respectively. Increasing the concentration of Mn²⁺ ion reduces the lifespan of the Eu²⁺ ion. This encourages an efficient energy exchange between these two ions. The UV light leakage issue in yellow LEDs was resolved by intergrating with n-UV InGaN chips and CaM. Powerful white LEDs were then created by mixing blue chlorophosphate with CaM. Its color coordinate was (0.3281,0.3071), and the associated color temperature (TC) was 6065 K, while the general hue rendering (Ra) and illuminating effectiveness (11 lm/W) were respectively 84.5 and 11 lm/W.