Rod-Shaped Nanographenes as Emitters in Fluorescent OLEDs

A significant challenge in the field of organic light-emitting diodes (OLEDs) technology is the development of stable, cost-effective, and sustainable emitters. Current emitters are frequently based on rare metals and heteroatom-based chromophores. Carbon-based nanomaterials, such as carbon dots (CDs) or nanographenes (NGs), offer a promising alternative due to their high photoluminescence quantum yields, the abundance of carbon materials, and the versatility of their syntheses. In this work, we fabricated green-light-emitting electroluminescent devices containing C 60 - t Bu 8 nanographene acting as the emitter. This nanographene contains 60 sp 2 carbon atoms and tert -butyl solubilizing group on the periphery; it was synthesized via the bottom-up approach. The C 60 - t Bu 8 was fully characterized, and it was incorporated into the emissive layer of a benchmark OLED stack (ITO/PEDOT:PSS/NG-containing active layer/BCP/TmPyPB/LiF/Al). The OLED devices containing the C 60 - t Bu 8 exhibited current and power efficiencies (CE and PE) of 2.27 cd·A –1, 0.28 lm·W –1 and luminance of 164 cd·m –2 . The performance remains modest in comparison to state-of-the-art OLEDs, but it outperforms previous attempts to utilize nanographenes as active materials for fluorescent OLEDs. Following the initial results, we also tested two other NGs ( C 78 - t Bu 6 and C 96 - t Bu 8 ), which contain 78 and 96 sp 2 carbon atoms as fluorescent emitters in OLEDs. The objective was to fine-tune the electroluminescence to yellow-orange and red light.