ABSTRACT Thermal luminescence stability is a key challenge in developing luminescent materials for various applications. Photoluminescent properties of two red‐emitting complexes, Eu (PHT) 3 ·H 2 O and Eu (PHT) 3 , were studied. Infrared spectroscopy demonstrated characteristic ν as (COO − ) and ν s (COO − ) bands of coordinated carboxylates. Photoluminescence confirms an effective ligand to metal energy transfer in the Eu (PHT) 3 ⸱H 2 O and Eu (PHT) 3 complexes, resulting in the characteristic Eu 3+ ion transitions corresponding to 5 D 0 → 7 F J ( J = 0–4). Luminescence lifetime (τ), Absolute Quantum Yield (Ф), and quantum efficiency (η) revealed an increase of nonradiative deactivation channels in the Eu (PHT) 3 ⸱H 2 O complex due to the presence of O–H oscillators when compared to the Eu (PHT) 3 complex. Photometric analysis placed both complexes in close agreement with NTSC red coordinates ( x = 0.67, y = 0.33), and full color‐purity values above 93%. The temperature‐dependent luminescence of the Eu (PHT) 3 complex exhibited thermal stability up to 423 K, maintaining a signal of 70%. In contrast, the initial intensity of the Eu (PHT) 3 ·H 2 O complex increases up to 50% in the 393–413 K range, causing intensity variations and reduced reproducibility suggested by the presence of the water molecule. These results indicate that the anhydrous Eu (PHT) 3 complex is an efficient red‐emitting phosphor for optoelectronic devices.
Guzmán‐Silva et al. (Thu,) studied this question.