Unveiling the phonon effect on the narrow-band deep-red emission from solution-combustion synthesized Mn4+ doped CaYAlO4 microcrystals

In this study, we report a unique solution-combustion synthesis of Mn 4+ doped CaYAlO 4 microcrystals and demonstrate a narrow-band deep-red emission. Through the simulation of low-temperature photoluminescence (PL) spectroscopy and theoretical fitting on temperature-dependent PL intensity at T  < 400 K, we obtained a dominant phonon mode with energy of 40 meV during the vibronic coupling process, with a small Huang-Rhys factor of S = 0.68. From the analysis of the measured PL lifetime evolution of Mn4 + doped CaYAlO 4 , it is found that luminescence thermal quenching effect was mainly attributed to four-dominant phonon interaction with Mn 4+ electronic states. More interestingly, the deviation of luminescence decay curve from the single-exponential mode at T  > 400 K suggests that the occurrence of two radiative transitions is a consequence of ionically thermal excitation to the second excited state of 4 T 2 . These findings provide not only a general approach to identify the predominant phonon vibration, but also deep insights into the effect of weak electron-phonon coupling on PL properties of solid-state luminescent.