Multi-sites energy transfer in Fe<sup>3+</sup>-doped KAl<sub>11</sub>O<sub>17</sub> phosphor toward zero thermal quenching near-infrared luminescence
Gaochao Liu, Shuai Zhang, Zhiguo Xia
Abstract
Near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) have demonstrated great potential for optoelectronic and biomedical applications, while the exploration of NIR phosphors with high thermal stability remains a challenge. Herein, we report an NIR phosphor KAl 11 O 17 :Fe 3+ with zero thermal quenching (TQ) behavior up to 200°C. The asymmetrical broadband NIR emission with three sub-bands centered at 700, 770, and 800 nm is related to the superposition of different Fe 3+ emission centers located in Al 2 O 4 , Al 3 O 6 , and Al 4 O 6 sites of the KAl 11 O 17 host, respectively. Temperature- and Fe 3+ concentration-dependent emission spectra verify that the energy transfer (ET) between multiple Fe 3+ emitters and the weak electron–phonon coupling (EPC) effect contribute to the thermally stable broadband NIR emission. The fabricated NIR pc-LED using optimized KAl 11 O 17 :Fe 3+ phosphor exhibits great potential in information encryption applications.