Electrically Modulated Fluorescence in Single Rare-Earth Particles

Rare earth (RE)-based complexes, due to their unique electronic structures, exhibit excellent fluorescence properties with high quantum yield and a long lifetime. From an application perspective, exploring RE-based complexes in luminescent optoelectronic devices asks for effective modulation approaches that control the luminescent properties. Here we report an electrically modulated fluorescence phenomenon in an RE-based complex, namely Eu₁₆(μ₄-F)₆(μ₃-F)₁₂(^<i>t</i>BuCOO)₁₈[N(CH₂CH₂O)₃]₄ (EuFC-16) particles, which effectively controls the optical behavior of individual particles. Frequency-dependent measurements and theoretical analysis reveal a charging mechanism on particles that rationalizes the voltage-modulated fluorescence. This charging-induced fluorescence modulation enables the localized capacitance mapping of individual RE particles at the single-pixel level. Moreover, modulation heterogeneity is observed within a single EuFC-16 particle, highlighting the importance of charge-distribution-controlled optical properties at the subparticle level. Our finding may offer a potential approach for controlling the luminescence of RE-based complexes with spatiotemporal controllability and potential scaling capability, which may enrich potential applications of RE-based electro-optical devices.