Achieving Efficient Near-Ultraviolet/Deep-Blue OLEDs and Sensitized Narrowband Green/Yellow OLEDs Utilizing Emitters with Planarized Intramolecular Charge Transfer

摘要

High-quality near-ultraviolet/deep-blue organic emitters are urgently needed but still rare. Here, three V-shape donor-acceptor-donor (D-A-D) emitters based on pyrazine cores, namely, VDMP-PhCz, VDMP-36PhCz, and VDMP-TPA, are designed and synthesized. Their doped devices using a high-polar host show remarkable electroluminescence (EL) performances with maximum external quantum efficiency (EQE) values up to 7.37%, 7.55%, and 9.03%, and corresponding CIE coordinates of (0.160,0.040), (0.161,0.039), and (0.149,0.072), respectively. Supported by theoretical calculations and experimental results, the high EL performances of these emitters are achieved by their planarized intramolecular charge transfer (PLICT) features, high triplet-excitons utilization from "hot exciton" channels, and high horizontal dipole orientations. Furthermore, these PLICT-based emitters can also function as efficient hosts for green or yellow multi-resonance (MR) narrowband emissive guests, providing high EQEs of over 32% with alleviated efficiency roll-offs.

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