NIR-SPINFLIP

NIR-Emitter mit Spinumkehr mit leicht verfügbaren Metallionen

01/08/2018 to 31/07/2021

Luminescent metal complexes are important building blocks in many applications such as organic light-emitting diodes. Currently, these technologies mainly rely on expensive metal precursors (e.g. featuring Ir, Ru, Pt). Luminophores with cheap and earth-abundant metal ions, that could function as substitutes, are rare up to now, despite the obvious drawback of using precious elements and the high economic value that new emitters could provide. A particularly interesting field in this context is the development of materials that emit in the near-infrared (NIR) spectral region. This is especially challenging due to the prevalence of a plethora of non-radiative decay pathways of electronically excited metal complexes, usually leading to strongly diminished luminescence efficiencies.
This project will develop molecular spin-flip NIR emitters based on earth-abundant metal ions with d2 and d3 electron configurations (primarily vanadium and molybdenum ions). The approach for the realization of efficient luminophores will rely on a comprehensive strategy to study and improve a number of fundamental parameters. Dominant decay paths via back-intersystem crossing (back-ISC) to non-emissive ligand field states will be blocked by employing ligand designs imposing a very strong ligand field. With the back-ISC process inhibited, the remaining decay path in the weak coupling limit via vibrationally induced multiphonon relaxation will be explored by deuteration and XH/XD overtone measurements. Finally, this relaxation pathway will be eliminated by selective deuteration.