NUV light induced visible emission in Er3+-activated NaSrLa(MoO4)O3 phosphors for green LEDs and thermometer

Er3+-activated NaSrLa(MoO4)O-3 phosphors were synthesized by a traditional solidstate reaction technique, which exhibited bright green emissions ascribing to the (H-2(11/2), S-4(3/2)) -> I-4(15/2) transitions of Er3+ ions under 377 nm excitation. The luminescence intensity increased with increasing the Er3+ ion concentration and achieved its maximum value when the doping concentration was 4 mol%. Moreover, the critical distance was estimated to be 25.32 angstrom, and the dipole-dipole interaction played a significant role in NR energy transfer between Er3+ ions in NaSrLa(MoO4)O-3 host lattices. At a forward bias current of 100 mA, the Light Emitting Diode (LED) device emitted a bright green emission with the color coordinate of (0.2547, 0.5996) that can be observed by the naked eye. Besides, based on the thermally coupled levels of H-2(11/2) and S-4(3/2), the temperature sensing performances of the prepared phosphors in the temperature range of 303-483 K were studied using the fluorescence intensity ratio technique. The maximum sensor sensitivity was about 0.0150 K-1 when the temperature was 483 K, and the Er3+ ion concentration largely influenced the sensor sensitivity of studied samples. Furthermore, the prepared phosphors exhibited excellent water resistance and thermal stability behavior. These characteristics demonstrated that the Er3+ activated NaSrLa(MoO4)O-3 phosphors were dual-functional materials for solid-state illumination and non-contact temperature measurement.