Cathodoluminescence degradation mechanism for europium coordination compound

Lanthanide-based coordination complexes represent a promising class of materials for cathodoluminescence (CL) applications, offering sharp emission profiles and spectral tunability. However, their practical use has been limited by poor stability under electron-beam irradiation, particularly in organic systems. In this work, we investigate the cathodoluminescence degradation behavior of a model europium coordination compound Eu₂(tph)₃(Phen)₂(H₂O)₂ (tph = terephthalate, Phen = o-phenanthroline) under electron-beam excitation through time-resolved measurements, Raman spectroscopy, and structural analysis. The CL emission exhibits a two-stage decay regime: a rapid initial drop attributed to radiolytic degradation, followed by a slower exponential decay consistent with thermal decomposition. Mechanistic assignments were validated by systematically varying film thickness, incorporating a high-κ polysiloxane thermal paste, and comparing CL behavior at different accelerating voltages (3 kV and 7 kV). Enhanced heat dissipation effectively suppressed thermal degradation, extending the operational voltage window and mitigating carbonization, as confirmed by post-irradiation optical and spectroscopic analyses. Notably, this study reports the slowest degradation rate yet observed for lanthanide-based cathodoluminophores, clarifies the dual nature of CL degradation in hybrid systems and highlights the importance of radiolysis suppression for future device development.