In this study, a novel green-emitting fluorapatite phosphor Ca 9 Tb(PO 4 ) 5 (SiO 4 )F 2 :Ce 3+ (CTPSF:Ce 3+ ), which features excellent luminous efficiency and thermal stability, was first designed and prepared. High-concentration doping of Tb 3+ enables efficient green emission. Moreover, photoluminescence (PL) spectra and diffuse reflectance spectra reveal that the introduction of Ce 3+ extends the excitation spectrum to the range spanning 200 nm–380 nm, with a significant improvement in efficiency, which stem from the Ce 3+ → Tb 3+ energy transfer process. The introduction of Ce 3+ boosts the photoluminescence intensity of CTPSF by 2.315-fold, delivering a great internal quantum efficiency (IQE) of 73.95 % and an external quantum efficiency (EQE) of 57.86 %. Additionally, the thermal stability improved from retaining 66.3 % of the original intensity at 150 °C to 83.6 % retention of its original intensity at 150 °C. Finally, White-light-emitting diode (WLED) devices were fabricated by employing BaMgAl 10 O 17 :Eu 2+ (blue), CaAlSiN 3 :Eu 2+ (red), and the synthesized CTPSF:Ce 3+ (green) phosphors. Upon applying a forward bias current of 60 mA, the WLED device displayed a high color rendering index (Ra) of 92.7 and a low correlated color temperature (CCT) of 3973 K, validating the potential of this green-emitting phosphor for practical applications in WLED lighting systems.
Lead halide perovskite nanocrystals (NCs) are highly promising for backlighting display applications due to their high photoluminescence quantum yields (PLQYs) and wide color gamut values. However, the practical applications of blue emitters are limited due to the toxicity of lead, unstable structure, and unsatisfactory PLQY. Herein, we report the successful synthesis of divalent europium-based perovskite CsEuBr3 NCs using a modified hot injection method. By optimizing the reaction conditions, the CsEuBr3 NCs display a deep-blue emission at 443 nm with a full width at half maximum (FWHM) of 28.5 nm, a color purity of 99.61%, and a record high PLQY of 93.51% for deep-blue narrow-band emissive lead-free perovskite NCs as far as we know. The emission mechanism of CsEuBr3 NCs is proved through first-principles calculations and spectral analysis. Notably, the CsEuBr3 NCs exhibit remarkable stability when exposed to high temperature, UV irradiation, and long-term sealed storage. The incorporation of CsEuBr3 NCs into polydimethylsiloxane (PDMS) serving as a converter is utilized for white light-emitting devices (WLEDs). WLEDs for backlight displays achieves a wide color gamut of 127.1% of the National Television System Committee standard (NTSC), 94.9% coverage of the ITU-R Recommendation BT.2020 (Rec.2020), and their half-lifetime is up to 1677 h, providing a promising pathway for highly efficient, environment-friendly and practical liquid crystal display backlights.
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