RESUMEN
In the research ecosystem's quest towards having deployable organic light-emitting diodes with higher-energy emission (e.g., blue light), we advocate focusing on fluorescent emitters, due to their relative stability and colour purity, and developing design strategies to significantly improve their efficiencies. We propose that all triplet-triplet annihilation upconversion (TTA-UC) emitters would make good candidates for triplet fusion-enhanced OLEDs ("FuLEDs"), due to the energetically uphill nature of the photophysical process, and their common requirements. We demonstrate this with the low-cost sky-blue 1,3-diphenylisobenzofuran (DPBF). Having satisfied the criteria for TTA-UC, we show DPBF as a photon upconverter (I th 92 mW cm-2), and henceforth demonstrate it as a bright emitter for FuLEDs. Notably, the devices achieved 6.5% external quantum efficiency (above the â¼5% threshold without triplet contribution), and triplet-exciton-fusion-generated fluorescence contributes up to 44% of the electroluminescence, as shown by transient measurements. Here, triplet fusion translates to a quantum yield (Φ TTA-UC) of 19%, at an electrical excitation of â¼0.01 mW cm-2. The enhancement is meaningful for commercial blue OLED displays. We also found DPBF to have decent hole mobilities of â¼0.08 cm2 V-1 s-1. This additional finding can lead to DPBF being used in other capacities in various printable electronics.
RESUMEN
The dinuclear complex [Cu2 I2 (L1)2 ] (1) (L1=3-((4-(pyridin-2-yl)-1H-1,2,3-triazol-1-yl)methyl)benzonitrile) is characterized by single-crystal X-ray diffraction (XRD), powder XRD, IR, photoluminescence spectroscopy, and thermogravimetric analysis. Unlike other related, known copper iodide complexes, it exhibits strong yellow emission in the solid state at both room temperature and 77â K. Showing good compatibility with PMMA, it is blended with the polymer in different weight ratios to prepare luminescent composite fibers.