Abstract
Carbene-metal-amides are soluble and thermally stable materials which have recently emerged as emitters in high-performance organic light-emitting diodes. Here we synthesise carbene-metal-amide photoemitters with CF3-substituted ligands to show sky-blue to deep-blue photoluminescence from charge-transfer excited states. We demonstrate that the emission colour can be adjusted from blue to yellow and observe that the relative energies of charge transfer and locally excited triplet states influence the performance of the deep-blue emission. High thermal stability and insensitivity to aggregation-induced luminescence quenching allow us to fabricate organic light-emitting diodes in both host-free and host-guest architectures. We report blue devices with a peak external quantum efficiency of 17.3% in a host-free emitting layer and 20.9% in a polar host. Our findings inform the molecular design of the next generation of stable blue carbene-metal-amide emitters.
Highlights
By varying the electron-donating or -withdrawing nature of carbazole substituents the HOMO–LUMO gap of CMA-type photoemitters can be readily adjusted and the electroluminescence colour can be tuned from yellow (CIE coordinates 0.35, 0.53) to deep blue (CIE 0.16, 0.05)
The glassy carbon macrodisk working electrode (GCE) was polished between experiments using alumina slurry (0.3 μm), rinsed in distilled water and subjected to brief sonication to remove any adhering alumina microparticles
The metal electrodes were dried in an oven at 100 °C to remove residual traces of water, the GCE was left to air dry and residual traces of water were removed under vacuum
Summary
The carbene ligand (AdL)[28,29,30], N-(2-chloro-4-(trifluoromethyl)phenyl)acetamide 14 and 15)[31], and complexes (AdL)MCl (M = Cu and Au)[32] were obtained according to literature procedures, see Supplementary Methods. All electrochemical experiments were performed using an Autolab PGSTAT 302N computer-controlled potentiostat. All electrochemical measurements were performed at ambient temperatures under an inert Ar atmosphere in an MeCN-containing complex under study (0.14 mM) and supporting electrolyte [n-Bu4N][PF6] (0.13 mM). Data were recorded with Autolab NOVA software Mass spectrometry data were obtained using APCI(ASAP) (Atmospheric Solids Analysis Probe) at the National Mass Spectrometry Facility at Swansea University
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
