Dicarbocation-Doped Polycyclic Aromatic Hydrocarbons with Efficient Deep-Red Narrowband Electroluminescence
Siyu Li, Zhihua Ma, Wenchao Xie, Kun Lyv, Junpeng Li, Ronghao Yang, Fangfang Huang, Yanpei Wang, Xin Ai, Zhicai Chen, Shiyang Shao
Abstract
Narrowband heteroaromatic emitters have garnered substantial attention for their applications in wide-color-gamut displays. Nevertheless, the design strategies for narrowband heteroaromatics in red-deep-red regions are limited. Here, we report novel dicarbocation-doped polycyclic aromatic hydrocarbon (PAH) emitters with deep-red narrowband emissions by embedding two positively charged carbocations (C + ) para -positioned to four nitrogen atoms within an undecacyclic aromatic skeleton. This molecular design generates a distinct multiresonance effect with strong short-range charge transfer between C + and nitrogen atoms to significantly reduce the energy gap to 1.80 ∼ 1.83 eV, realizing deep-red emission at 678 ∼ 684 nm with narrow full width at half maxima of 42 ∼ 44 nm (0.114 ∼ 0.117 eV). Remarkably, solution-processed organic light-emitting diodes utilizing the emitters achieved efficient deep-red narrowband electroluminescence with maximum external quantum efficiencies of 20.4% and CIE coordinates of (0.720, 0.280) that exceed the BT.2020 gamut standard for red emission. This study establishes multicarbocation-doped PAHs as a new paradigm for developing efficient, long-wavelength narrowband emitters in addition to conventional neutral heteroaromatic emitters.