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

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.

Excitation Wavelength Engineering through Organic Linker Choice in Luminescent Atomic/Molecular Layer Deposited Lanthanide-Organic Thin Films.

We demonstrate multiple roles for the organic linker in luminescent lanthanide-organic thin films grown with the strongly emerging atomic/molecular layer deposition technique. Besides rendering the hybrid thin film mechanically flexible and keeping the lanthanide nodes at a distance adequate to avoid concentration quenching, the organic moieties can act as efficient sensitizers for the lanthanide luminescence. We investigate six different aromatic organic precursors in combination with Eu3+ ions to reveal that by introducing different nitrogen species within the aromatic ring, it is possible to extend the excitation wavelength area from the UV range to the visible range. This opens new horizons for the application space of these efficiently photoluminescent thin-film materials.

Amorphous-to-crystalline transition and photoluminescence switching in guest-absorbing metal-organic network thin films.

An amorphous metal-organic framework (aMOF) is an oxymoron as the porosity derived from the ordered network of the metal and organic moieties is the main characteristic of conventional crystalline MOFs. However, amorphous metal-organic materials can be synthesized from gaseous precursors through atomic/molecular layer deposition (ALD/MLD). We demonstrate an exciting interplay between luminescence properties and amorphous-to-crystalline transition realized upon water absorption in ALD/MLD aMOF films.