一种以 Spiro 为桥的供体 π 受体型红色热激活延迟荧光发射器，在有机发光二极管中表现出聚集诱导发射活性和出色的效率,Advanced Optical Materials

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一种以 Spiro 为桥的供体 π 受体型红色热激活延迟荧光发射器，在有机发光二极管中表现出聚集诱导发射活性和出色的效率
Advanced Optical Materials ( IF 8.0 ) Pub Date : 2023-05-21 , DOI: 10.1002/adom.202300368
Hui Wang ₁ , Jia‐Xiong Chen ₂ , Xi Zhang ₁ , Ying‐Chun Cheng ₁ , Xiao‐Chun Fan ₁ , Lu Zhou ₁ , Jia Yu _{1,

3} , Kai Wang _{1,

4} , Xiao‐Hong Zhang _{1,

3}

Affiliation

利用苯基作为π桥连接供体(D)和受体(A)单元构建供体-π-受体(D-π-A)型分子结构已被认为是开发高效红光的有效方法热激活延迟荧光（TADF）有机发光二极管（OLED）。然而，灵活且相对平面的结构将打开潜在的能量损失通道，例如非辐射失活和聚集引起的三线态猝灭过程。在这里，首先实现了一个大的螺-9,9'-二芴单元作为桥连基团来构建D- π-A分子，使其与普通苯基桥相比具有更高的整体刚性、更充分的空间位阻、更长的分子长度以及明显的聚集诱导发光特性。结果，在单分子水平上有效缓解了能量耗散路径，同时减轻了生色团间的猝灭，从而实现了 100% 的光致发光量子产率和高达 89% 的水平偶极子比。基于3-(2-(二苯氨基)-9,9'-螺二[芴]-7-基)二苯并[a,c]吩嗪-11,12-二甲腈的OLED表现出优异的外量子效率，接近37%在 612 nm 处，与基于苯基桥的对照分子相比，增强了 1.38 倍以上。这项工作为利用 D- π设计高效红色 TADF 发射器提供了一个指导性的解决方案-A型分子结构。

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A Donor-π-Acceptor Type Red Thermally Activated Delayed Fluorescence Emitter Featuring Spiro as the Bridge Exhibiting Aggregation-Induced Emission Activity and Outstanding Efficiencies in Organic Light-Emitting Diodes

Constructing donor-π-acceptor (D-π-A)-type molecular structures by employing a phenyl as the π-bridge to link donor (D) and acceptor (A) units has been recognized as an effective way to develop highly efficient red thermally activated delayed fluorescence (TADF) organic light-emitting diodes (OLEDs). However, flexible and relatively planar structures would open potential energy loss channels, such as nonradiative inactivation and aggregation-induced triplet quenching processes. Here, a bulky spiro-9,9′-bifluorene unit is first implemented to serve as a bridging group to construct a D-π-A molecule, enabling it to have higher overall rigidity, more sufficient steric hindrance, prolonged molecule length, and obvious aggregation-induced emission characteristics compared with a common phenyl bridge. As a result, energy dissipation routes are effectively relieved at the unimolecular level, together with mitigated interchromophore quenching, rendering a 100% photoluminescence quantum yield and a larger horizontal dipole ratio of 89%. The OLED based on 3-(2-(diphenylamino)-9,9′-spirobi[fluoren]-7-yl)dibenzo[a,c]phenazine-11,12-dicarbonitrile exhibits an excellent external quantum efficiency of nearly 37% at 612 nm, which is over 1.38-fold enhancement compared with the phenyl bridge-based control molecule. This work provides an instructive solution to design highly efficient red TADF emitters exploiting D-π-A-type molecular structures.

更新日期：2023-05-21

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