In this study, we report two efficient intramolecular charge transfer (ICT) compounds with versatile functionality as hole transporting layers (HTL) and hosts in emission layer (EML) of phosphorescent organic light emitting diodes (Ph-OLEDs) with donor-acceptor-donor structures. In both molecules, 9,9′-spirobifluorene (SBF) was employed as a common electron acceptor, while phenoxazine (PXZ) or phenothiazine (PTZ) were used as donors. The molecules 2,7-di(10H-phenoxazin-10-yl)-9,9′-spirobi[fluorene] (SBF-PXZ) and 2,7-di(10H-phenothiazin-10-yl)-9,9′-spirobi[fluorene] (SBF-PTZ) were synthesized via a Buckwald-Hartwig cross-coupling reaction in a single step that exhibited typical ICT phenomena. The extremely twisted geometrical configurations of SBF-PXZ and SBF-PTZ may allow for effective intramolecular charge-transfer. Both molecules exhibited strong absorption and emission characteristics in the visible region in solution as well as in the thin film form; significant positive solvatochromism was also observed for both compounds. The replacement of PTZ donor with the PXZ donor caused a bandgap reduction together with an improved ionization potential (IP). The deeper IP (>5.1 eV), greater glass transition temperature, and higher hole mobility extracted from the hole only devices of both molecules revealed them as superior candidates for HTL applications (with/without exciton blocking layers) in Ph-OLEDs. It is further corroborated by the enhanced half-life time of Ph-OLEDs with SBF-PXZ/SBF-PTZ HTLs. Moreover, the OLED performances with SBF-PTZ and SBF-PXZ as EMLs and hosts for phosphorescent dopant OLEDs have exemplified the versatility of the proposed ICT compounds.

在这项研究中，我们报告了两种高效的分子内电荷转移（ICT）化合物，具有多功能功能，如空穴传输层（HTL）和带有施主-受主-施主的磷光有机发光二极管（Ph-OLED）的发射层（EML）中的主体结构。在这两个分子中，均使用9,9'-螺双芴（SBF）作为常见的电子受体，而使用苯恶嗪（PXZ）或吩噻嗪（PTZ）作为供体。分子2,7-二（10 H-苯恶嗪-10-基）-9,9'-螺双[芴]（SBF-PXZ）和2,7-二（10 H通过一个典型的ICT现象，通过Buckwald-Hartwig交叉偶联反应，一步合成了[phenothiazin-10-yl）-9,9'-spirbibi [芴]（SBF-PTZ）。SBF-PXZ和SBF-PTZ的极其扭曲的几何构型可以实现有效的分子内电荷转移。两种分子在溶液以及薄膜形式的可见光区域均表现出较强的吸收和发射特性。对于这两种化合物，也观察到显着的阳性溶剂变色。用PXZ供体替代PTZ供体导致带隙减小以及电离势（IP）改善。IP越深（> 5.1 eV），玻璃化转变温度越高，从这两种分子的仅空穴器件中提取的更高的空穴迁移率显示出它们是Ph-OLED中HTL应用（有/无激子阻挡层）的优异候选者。具有SBF-PXZ / SBF-PTZ HTL的Ph-OLED的半衰期延长，进一步证实了这一点。此外，以SBF-PTZ和SBF-PXZ作为EML和磷光掺杂剂OLED的基质的OLED性能已证明了所提出的ICT化合物的多功能性。