Phosphors-converted LEDs (pc-LEDs) are excellent artificial light sources for indoor plant cultivation, in which the far-red-emitting component (700−780 nm) plays an important role in regulating the photomorphogenesis of plants. Accordingly, highly efficient and thermally stable far-red-emitting phosphors are indispensable for developing high-performance plant cultivation pc-LEDs. Herein, far-red-emitting YAl
3(BO
3)
4:Cr
3+ (YAB:Cr
3+) phosphors were synthesized by solid-state reaction, and their photoluminescence characteristics, thermal quenching, quantum yield (QY), and application in pc-LEDs were systematically investigated. The YAB:Cr
3+ phosphor has an intense broadband absorption to the blue light, simultaneously exhibiting the sharp-line
2E emission and the broadband
4 T
2 emission of Cr
3+ with a QY of ~86.7%. The far-red broadband emissions of YAB:Cr
3+ centered at ~735 nm show a high resemblance to the active-state (
PFR) absorption of plant phytochrome. Moreover, the YAB:Cr
3+ phosphor shows the thermally enhanced luminescence at temperatures of 303−393 K and the near-zero thermal quenching up to 423 K. The anomalous thermal enhancement is attributed to the temperature-dependent repopulation between
2E and
4 T2 states. Finally, a pc-LED device was fabricated with the YAB:Cr
3+ phosphor and blue chip, exhibiting the light out power of ~50.6 mW and energy conversion efficiency of ~17.4% at 100 mA drive current, respectively. The exceptional PL features including suitable excitation/emission wavelengths, suppressed thermal quenching and high QY make YAB:Cr
3+ phosphors very promising for applications in plant growth pc-LEDs.
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