Four donor-π-acceptor (D-π-A) luminophores based on π-extended imidazole-fluorene hybrid, namely PhIF-1, PyIF-1, PhIF-2 and PyIF-2, are developed. Two imidazole derivatives, phenanthreneimidazole (PhI) and pyreneimidazole (PyI), are investigated to highlight their potential applications in deep-blue electroluminescence. A mild electron pull-push system between PhI/PyI and fluorene is achieved, enabling the mixture of locally excited (LE) and charge transfer (CT) excited state character. Systematic study is also carried out to reveal the influence of n-hexyl chain at the 9-position of fluorene on the photophysical properties of these new emitters. We find that the introduction of alkyl chain can tune photophysical properties, leading to better solid-state emission in PhIF-2 and PyIF-2. All the new compounds show intense high-energy fluorescence with excellent thermal properties suitable for organic light-emitting diode (OLED) application. Non-doped OLEDs exhibiting maximum external quantum efficiency (EQE) of 3.65% and 3.75% are realized using PhIF-1 and PyIF-1, respectively. Compared with PhIF-1 and PyIF-1, alkyl chain substituted PhIF-2 and PyIF-2 exhibit better blue color purities of (0.15, 0.12) and (0.15, 0.13), respectively. In addition, better color purity and higher luminescence efficiency are acquired simultaneously in doped devices. An OLED employing 20 wt% PyIF-1 as emitting core displays a high EQE of 4.29% at 1000 cd m⁻² (EQE_max = 4.60%). This work may provide a rational design for π-extended imidazole D-π-A luminophores for deep-blue electroluminescence applications.

基于π扩展的咪唑-芴杂化体的四个供体π受体（D-π-A）发光体，即PhIF-1，PyIF-1，PhIF-2和PyIF-2，已开发。研究了两种咪唑衍生物，菲咪唑（PhI）和pyr咪唑（PyI），以突出它们在深蓝色电致发光中的潜在应用。在PhI / PyI与芴之间实现了温和的电子推挽系统，实现了局部激发（LE）和电荷转移（CT）激发态特性的混合。还进行了系统的研究，以揭示芴9位上的正己基链对这些新发射体的光物理性质的影响。我们发现引入烷基链可以调节光物理性质，从而在PhIF-2和PyIF-2中产生更好的固态发射。所有这些新化合物均显示出强烈的高能荧光，并具有出色的热性能，适用于有机发光二极管（OLED）应用。使用PhIF-1和PyIF-1分别实现了最大外部量子效率（EQE）为3.65％和3.75％的非掺杂OLED 。与PhIF-1和PyIF-1相比，烷基链取代的PhIF-2和PyIF-2分别具有更好的蓝色纯度（0.15，0.12）和（0.15，0.13）。另外，在掺杂的器件中同时获得了更好的色纯度和更高的发光效率。使用20 wt％PyIF-1作为发射核心的OLED在1000 cd m处显示出4.29％的高EQE^-2（_最大EQE  = 4.60％）。这项工作可以为深蓝色电致发光应用的π扩展咪唑D-π-A发光体提供合理的设计。