The incorporation of tert-butyl groups and spiro-functionalization into C═O/N-embedded multiresonance thermally activated delayed fluorescence (MR-TADF) systems has yielded materials with superior narrowband emission and excellent color purity. To elucidate the mechanisms underlying the enhanced properties, we present a theoretical study of a series of fused nitrogen/carbonyl derivatives with narrower emission profiles. The key steric factors that contribute to narrowband emission were identified through energy decomposition analysis, induced by structural relaxation in states S₀ and S₁. Additionally, we achieved potential narrower-band and deep-blue emission by targeting the suppression of vibrational coupling effects. This work provides compelling evidence that a 1-tert-butyl substitution, acting as an end lock, offers minimal reorganization energy and optimal structural stability when combined with a fused lock. Furthermore, new compounds such as 1tBuCZQ and 1tBuDQAO have been identified as promising MR-TADF emitters, delivering ultranarrowband emission as high-quality organic light-emitting diodes.

中文翻译：

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氮/羰基多谐振热激活延迟荧光发射器中窄带发射的来源：空间锁和振动耦合效应


将叔丁基和螺功能化掺入 C═O/N 嵌入式多共振热激活延迟荧光 （MR-TADF） 系统中，产生了具有优异窄带发射和出色色纯度的材料。为了阐明增强特性背后的机制，我们提出了一系列具有较窄发射曲线的熔融氮/羰基衍生物的理论研究。通过能量分解分析确定了导致窄带发射的关键空间因子，该分析由状态 S₀ 和 S₁ 的结构松弛诱导。此外，我们通过抑制振动耦合效应实现了潜在的窄带和深蓝色发射。这项工作提供了令人信服的证据，表明 1-叔丁基取代作为端锁，当与熔融锁结合时，可提供最小的重组能量和最佳的结构稳定性。此外，1tBuCZQ 和 1tBuDQAO 等新化合物已被确定为有前途的 MR-TADF 发射器，作为高质量的有机发光二极管提供超窄带发射。