New NIR emitting phosphor for blue LEDs with stable light output up to 180 °C

A new luminescent material for the conversion of blue light to near-infrared (NIR) radiation is presented. The new phosphor Sr2Si5N8:Eu,Nd displays a large absorption cross section in the blue spectral region and allows stable NIR operation when combined with blue emitting (In,Ga)N LEDs, despite the high excitation densities and elevated temperatures near the LED chip. The luminescence properties of the material were measured as function of energy, time, temperature, and excitation density. In contrast to state-of-the-art (Al,Ga)As NIR LEDs which suffer from severe thermal quenching and shift of the peak emission already at around 100 °C, the presented phosphor system displays high emission intensity with constant spectral power distribution up to 180 °C.