Photophysical properties of Eu3+ complexes approaching electronic contact to a metal surface

TL;DR

This study investigates the photophysical behavior of Eu3+ complexes near metal surfaces, revealing stability differences that impact their potential in electroluminescent devices.

Contribution

It provides a comparative analysis of Eu3+ complexes in various film configurations, highlighting stability and emission properties relevant for device applications.

Findings

Eu3+(trensal) complexes are more stable on metal surfaces than beta diketonate complexes.

Photoluminescence properties vary with film thickness and substrate.

Eu3+ complexes show promise for electroluminescent device integration.

Abstract

The application of rare-earth complexes in electrically driven light sources poses a series of challenges that require specific optimization of the molecular photophysical properties. Here, we present a report on films of three different Eu3+ complexes characterized in terms of emission spectra and fluorescence decay. We compare molecular complexes in powder form and sublimed films, in films on glass and on a metal surface, and in films of thicknesses down to less than 3 nm (< 3 ML), approaching electrical coupling. Our photoluminescence experiments supported by scanning tunneling microscopy of sub-monolayers indicate that Eu3+(trensal) complexes are less affected by sublimation and more stable on the metal surface than typical beta diketonate complexes, making them promising candidates for electroluminescence devices.