An acridine and naphthalene-fused chromophore for Rec. 2020 standard deep-blue OLEDs with high color purity and low-efficiency roll-off

Abstract

Deep-blue electroluminescent materials with high color purity and efficiency play a decisive role in ultra-high-definition organic light-emitting diodes (UHD-OLEDs). However, the development of emitters exhibiting both narrowband emission and high efficiency with negligible roll-off is significant but challenging. In this study, to achieve efficient deep-blue emission, naphthalene was fused with 9,9-dimethyl-9,10-dihydroacridine (DMAC) to weaken the electron-donating ability and increase the conjugation degree of DMAC. Three compounds with a fused 12,12-dimethyl-7,12-dihydrobenzo[a]acridine (DMBA) moiety, NATPA, NAPCZ, and NAPPI, were successfully synthesized and exhibited desired deep-blue emission and good thermal stability. Different peripheral donor and acceptor groups attached to DMBA could modulate the excited state characteristic and carrier mobilities. Benefiting from structural vibration inhibited by the fused structure, doped devices based on these three emitters exhibited deep-blue emissions (λ_ELs ≤ 434 nm) with narrowband spectra (FWHMs ≤ 45 nm) and near Rec. 2020 blue standard CIE coordinates (x: 0.153–0.155, y: 0.044–0.055). Among them, the NAPPI-based device achieved a maximum external quantum efficiency of 5.17% with low-efficiency roll-off (4.6%@500 cd m⁻²). These results further verify the effectiveness and potentiality of the fused DMBA chromophore for deep-blue emitters.