Deep‐blue multi‐resonance (MR) emitters with stable and narrow full‐width‐at‐half‐maximum (FWHM) are of great importance for widening the color gamut of organic light‐emitting diodes (OLEDs). However, most planar MR emitters are vulnerable to intermolecular interactions from both the host and guest, causing spectral broadening and exciton quenching in thin films. Their emission in the solid state is environmentally sensitive, and the color purity is often inferior to that in solutions. Herein, a molecular design strategy is presented that simultaneously narrows the FWHM and suppresses intermolecular interactions by combining intramolecular locking and peripheral shielding within a carbonyl/nitrogen‐based MR core. Intramolecularly locking carbonyl/nitrogen‐based bears narrower emission of 2,10‐dimethyl‐12,12‐diphenyl‐4H‐benzo[9,1]quinolizino[3,4,5,6,7‐defg]acridine‐4,8(12H)‐dione in solution and further with peripheral‐shielding groups, deep‐blue emitter (12,12‐diphenyl‐2,10‐bis(9‐phenyl‐9H‐fluoren‐9‐yl)−4H‐benzo[9,1]quinolizino[3,4,5,6,7‐defg]acridine‐4,8(12H)‐dione, DPQAO‐F) exhibits ultra‐pure emission with narrow FWHM (c.a., 24 nm) with minimal variations (∆FWHM ≤ 3 nm) from solution to thin films over a wide doping range. An OLED based on DPQAO‐F presents a maximum external quantum efficiency (EQEmax) of 19.9% and color index of (0.134, 0.118). Furthermore, the hyper‐device of DPQAO‐F exhibits a record‐high EQEmax of 32.7% in the deep‐blue region, representing the first example of carbonyl/nitrogen‐based OLED that can concurrently achieve narrow bandwidth in the deep‐blue region and a high electroluminescent efficiency surpassing 30%.

中文翻译：

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通过协同锁定和屏蔽羰基/氮基 MR-TADF 发射器逐步实现纯蓝色有机发光二极管

具有稳定且窄半峰全宽（FWHM）的深蓝色多谐振（MR）发射器对于拓宽有机发光二极管（OLED）的色域具有重要意义。然而，大多数平面MR发射器容易受到主客体分子间相互作用的影响，导致薄膜中的光谱展宽和激子猝灭。它们的固态发射对环境敏感，并且颜色纯度通常不如溶液中的发射。在此，提出了一种分子设计策略，通过在基于羰基/氮的 MR 核内结合分子内锁定和外围屏蔽，同时缩小半高宽并抑制分子间相互作用。分子内锁定羰基/氮基具有较窄的2,10-二甲基-12,12-二苯基-4H-苯并[9,1]喹嗪基[3,4,5,6,7-defg]吖啶-4,8的发射(12H)-二酮在溶液中并进一步带有外围屏蔽基团，深蓝色发光体(12,12-二苯基-2,10-双(9-苯基-9H-芴-9-基)-4H-苯并[9 ,1]喹嗪基[3,4,5,6,7-defg]吖啶-4,8(12H)-二酮, DPQAO-F) 表现出超纯发射, 窄 FWHM (约, 24 nm), 变化最小 (在很宽的掺杂范围内，从溶液到薄膜，ΔFWHM ≤ 3 nm）。基于 DPQAO-F 的 OLED 具有最大外量子效率（EQE最大限度）为19.9%，色彩指数为（0.134，0.118）。此外，DPQAO-F 的超级设备表现出创纪录的高 EQE最大限度深蓝色区域的发光效率为32.7%，这是第一个可以同时实现深蓝色区域窄带宽和超过30%的高电致发光效率的羰基/氮基OLED的例子。