Closely aligned configuration of the donor (D) and acceptor (A) is crucial for the light-emitting efficiency of thermally activated delayed fluorescence (TADF) materials with through-space charge transfer (TSCT) characteristics. However, precisely controlling the D–A distance of blue TSCT-TADF emitters is still challenging. Herein, an extra donor (D*) located on the side of the primary donor (D) is introduced to construct the hydrogen bonding with A and thus modulate the distance of D and A units to prepare high-efficiency blue TSCT emitters. The obtained “V”-shaped TSCT emitter presents a minimal D–A distance of 2.890 Å with a highly parallel D–A configuration. As a result, a high rate of radiative decay (>10⁷ s^–1) and photoluminescence quantum yield (nearly 90%) are achieved. The corresponding blue organic light-emitting diodes show maximum external quantum efficiencies (EQE_max) of 27.9% with a Commission Internationale de L’Eclairage (CIE) coordinate of (0.16, 0.21), which is the highest device efficiency of fluorene-based blue TSCT-TADF emitters. In addition, the TSCT-TADF emitter-sensitized OLEDs also achieve a high EQE_max of 29.3% with a CIE coordinate of (0.12, 0.16) and a narrow emission.

中文翻译：

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通过分子内氢键诱导的固定构型提高蓝色空间电荷转移发射器的发光效率

供体 (D) 和受体 (A) 的紧密排列配置对于具有穿越空间电荷转移 (TSCT) 特性的热激活延迟荧光 (TADF) 材料的发光效率至关重要。然而，精确控制蓝色 TSCT-TADF 发射器的 D-A 距离仍然具有挑战性。在此，引入位于主供体（D）一侧的额外供体（D*）来与A构建氢键，从而调节D和A单元的距离，以制备高效蓝色TSCT发射器。所获得的“V”形 TSCT 发射器具有 2.890 Å 的最小 D-A 距离，具有高度平行的 D-A 配置。结果，实现了高辐射衰减率（>10 ⁷ s ^–1 ）和光致发光量子产率（接近90%）。相应的蓝色有机发光二极管的最大外量子效率（EQE _max）为27.9%，国际照明委员会（CIE）坐标为（0.16，0.21），这是芴基蓝色有机发光二极管的最高器件效率TSCT-TADF 发射器。此外，TSCT-TADF发射极敏化OLED还实现了29.3%的高EQE _max、CIE坐标为(0.12,0.16)和窄发射。