Dy3+-Assisted Negative-Thermal Quenching in Ho3+-Doped SrMoO4 for Luminescence Thermometry and Lighting Applications

Luminescence thermometry has been a research hotspot due to its rapid response, noninvasive approach, and high spatial resolution. However, achieving good relative sensitivity with minimal temperature uncertainty remains a daunting challenge. Adding to the ongoing research, our work focuses on the luminescence thermometry application of the Dy3+/Ho3+-codoped SrMoO4 phosphor. The negative thermal quenching in Dy3+ emission is observed in the SrMoO4 host. Interestingly, the codoping of Dy3+ in SrMoO4:Ho3+ changes the thermal quenching behavior of Ho3+ from positive to negative. The intriguing nature of thermal quenching of Dy3+ and Ho3+ in SrMoO4 is exploited for luminescence thermometry. Due to the different responses of the Ho3+ transitions to temperature, the relative sensitivity is calculated for three different combinations of the intensity ratio. The best sensitivity of about 0.39% K-1 at 300 K is evaluated for I (Dy(572))/I-Ho(541). The repeatability measurement manifests the excellent thermal stability of the luminescence. The temperature uncertainty is found to be within 0.8 K. The Ho3+-doped SrMoO4 is also probed for the lighting application. The Ho3+ ions emit green emissions and exhibit excellent thermal stability by retaining similar to 80% of their luminescence at 420 K with a 0.23 eV activation energy. The SrMoO4:Ho3+ phosphor exhibits excellent resistance to color drift with rising temperatures. Overall, the insights presented in our study will broaden the scope of rare-earth-doped SrMoO4 phosphors in the fields of optical thermometry and lighting applications.