Dendritic Carbene Metal Carbazole Complexes as Photoemitters for Fully Solution-Processed OLEDs


Authors: AS Romanov, L Yang, STE Jones, D Di, O Morley, BH Drummond, APM Reponen, M Linnolahti, D Credgington, M Bochmann

Light-emitting carbene-metal amide complexes bearing first- and second-generation carbazole dendron ligands are reported, (AdL)M(Gn), (M = Cu and Au; Gn carbazole dendrimer generation, where n = 1 and 2; AdL = adamantylsubstituted cyclic (alkyl)(amino)carbene). The thermal stability of the complexes increases with each dendrimer generation. Cyclic voltammetry indicates that the highest occupied molecular orbital/lowest unoccupied molecular orbital energy levels are largely unaffected by the size of the dendron, while first reduction and oxidation processes show a quasi-reversible character. The gold complexes in toluene at room temperature show photoluminescent quantum yields of up to 51.5% for the first and 78% for the second generation. Varied temperature transient photoluminescence decay is consistent with a thermally activated process, indicating a delayed fluorescence-type emission mechanism. Neat films show excited state lifetimes composed of prompt and dominant sub-microsecond delayed components, with radiative constants of up to 10$^6$s$^{−1}$. Solution-processed organic light-emitting diodes for first-generation copper and gold dendrimers (AdL)M(G1) have been fabricated with external quantum efficiencies of 5.5% for copper and 10.3% for gold at practical brightness.

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Recommended citation: A. S. Romanov. (2019). “Dendritic Carbene Metal Carbazole Complexes as Photoemitters for Fully Solution-Processed OLEDs.” Chem. Mater.. 31.