Luminescent carbene–copper(i)–amide polymers for efficient host-free solution-processed OLEDs†

Abstract

Luminescent metallopolymers have attracted broad interest in the fields of healthcare and organic electronics. However, polymeric emitters based on earth-abundant metal complexes are scarce. Here, two series of Cu(I) polymers, PMAC-x and PCAAC-x (x = 1–3) have been developed using two kinds of Cu(I)-based carbene–metal–amide (CMA) complexes as side-chain emitter units to combine with a nonconjugated polystyrene backbone. These Cu(I) polymers emit via distinct thermally activated delayed fluorescence or dominant phosphorescence, inherited from the grafted Cu(I)-based CMA units. Particularly, the PMAC-x polymers exhibit high photoluminescence quantum efficiencies of up to 0.78, short emission lifetimes of down to 0.66 μs, and fast radiative rates of up to 10⁶ s⁻¹ in neat films. Thanks to the good encapsulation effect of the polystyrene backbone, these Cu(I) polymers not only demonstrate favorable moisture stability but also show significant aggregation-induced emission. The resultant host-free solution-processed organic light-emitting diodes (OLEDs) achieve outstanding electroluminescence performance with a record external quantum efficiency of 13.8% at a practical luminance of ∼100 nits, representing state-of-the-art device efficiency for metallopolymer-based OLEDs. This work not only presents the first example of CMA polymers but also provides the future direction of polymeric emitters from earth-abundant metal complexes for the OLED application.