Although many small molecules have been reported to show efficient TADF, reports of polymers that support TADF are rare. And those who report about polymers have TADF chromophores linked to a polymer network, retaining their monomeric properties.
A team of researchers from the Technical University in Dresden, Germany, led by Prof. B. Voit and Prof. S. Rieneke discuss in their recent paper in Advanced Functional Materials a new strategy that un-locks an additional molecular design rule reserved exclusively for polymeric materials. By introducing a controlled extension of the conjugation of the monomers HOMO wavefunction, the authors observed a destabilization of the latter, which lead to a decreased singlet-triplet splitting and, ultimately, efficient TADF in the polymer. The monomer unit, or the individual repeating unit in the polymer, on the contrary is a poor emitter having inefficient phosphorescence as primary emission channel. As a result, a transition of the photoluminescence quantum yield from about 3% (monomer and model compound for repeating unit) to about 71% (polymer) was observed.
The full article can be found here.