Atomic/molecular layer deposition of europium–organic thin films on nanoplasmonic structures towards FRET-based applications

Abstract

We present a novel atomic/molecular layer deposition (ALD/MLD) process for europium–organic thin films based on Eu(thd)₃ and 2-hydroxyquinoline-4-carboxylic acid (HQA) precursors. The process yields with appreciably high growth rate luminescent Eu-HQA thin films in which the organic HQA component acts as a sensitizer for the red Eu³⁺ luminescence, extending the excitation wavelength range up to ca. 400 nm. We moreover deposit these films on nanoplasmonic structures to achieve a twentyfold enhanced emission intensity. Finally, we demonstrate the FRET-type energy transfer process for our Eu-HQA coated nanoplasmonic structures in combination with commercial Alexa647 fluorophor, underlining their potential towards novel bioimaging applications.