Vibronic coupling parameters and luminescent properties of bivalent europium ion doped alkaline earth thioaluminates

To obtain blue and green electroluminescent phosphor of high efficiency, vibronic coupling parameters and luminescent properties of M^IIAl₂S₄:Eu materials were researched. Configuration coordinate model, which is the base of assessment, was introduced and assessing parameters were listed firstly. Photoluminescent (PL) and electroluminescent (EL) properties of M^IIAl₂S₄:Eu were compared and analyzed by the PL and EL spectra. Additionally, performances of M^IIAl₂S₄:Eu phosphor materials were evaluated with the calculation of characteristic energy and unitless factors by PL spectra. According to the result of assessment and the comparison of CIE1931 color coordinates, it can be concluded that BaAl₂S₄:Eu and CaAl₂S₄:Eu are suitable for blue and green emitting phosphor. Mg and Sr thioaluminates can be used as parts of complex thioaluminate phosphors because they can shift the emission peaks.