Topological Design of Highly Anisotropic Aligned Hole Transporting Molecular Bottlebrushes for Solution-Processed OLEDs
Topological Design of Highly Anisotropic Aligned Hole Transporting Molecular Bottlebrushes for Solution-Processed OLEDs
复制标题
用于溶液加工 OLED 的高度各向异性对齐空穴传输分子瓶刷的拓扑设计
DOI：
10.1021/jacs.2c00420
复制
发表时间：
2022
影响因子：
15
通讯作者：
Borguet, Yannick P.
中科院分区：
文献类型：
--
作者：
Kang, Nari;Cho, Sangho;Leonhardt, Eric E.;Liu, Chun;Verkhoturov, Stanislav V.;Woodward, William Henry;Eller, Michael J.;Yuan, Tianyu;Fitzgibbons, Thomas C.;Borguet, Yannick P.
在溶液处理的空穴传输层（HTL）技术中，已经对具有垂挂空穴传输功能的聚氯乙烯聚合物进行了广泛的探索，然而，在HTL薄膜中，这些聚合物的HT部分的高各向异性填充到衬底平行方向的例子很少。对于小分子，基板平行对准HT基团是一种完善的方法，以提高整体器件性能。为了解决从气相沉积小分子延伸到溶液可加工聚合物体系的长期挑战，本文报道了一种基本的化学策略，通过构建具有瓶刷拓扑结构的HT聚合物，在大分子框架内定位HT侧链。采用最先进的聚合物合成技术，各种功能亚基，包括三苯胺（TPA）的空穴传输和粘附到衬底，以及全氟烷基取代苯氧基苯乙烯的迁移到空气界面，通过对整个瓶刷拓扑结构的组成和位置的精细控制进行了组织。通过自旋铸造和热退火将HT瓶刷（HTB）聚合物组装成单层HTB薄膜，HTB的骨架垂直排列，而带有悬垂tpa的接枝枝平行于衬底延伸。整体设计实现了HTLs中沿衬底面外方向的高TPA π叠加，使有机发光二极管的效率比线性聚乙烯醇三苯胺二极管提高了一倍。
Polyvinyl polymers bearing pendant hole transport functionalities have been extensively explored for solution-processed hole transport layer (HTL) technologies, yet there are only rare examples of high anisotropic packing of the HT moieties of these polymers into substrate-parallel orientations within HTL films. For small molecules, substrate-parallel alignment of HT moieties is a well-established approach to improve overall device performance. To address the longstanding challenge of extension from vapor-deposited small molecules to solution-processable polymer systems, a fundamental chemistry tactic is reported here, involving the positioning of HT side chains within macromolecular frameworks by the construction of HT polymers having bottlebrush topologies. Applying state-of-the-art polymer synthetic techniques, various functional subunits, including triphenylamine (TPA) for hole transport and adhesion to the substrate, and perfluoro alkyl-substituted benzyloxy styrene for migration to the air interface, were organized with exquisite control over the composition and placement throughout the bottlebrush topology. Upon assembling the HT bottlebrush (HTB) polymers into monolayered HTL films on various substrates through spin-casting and thermal annealing, the backbones of HTBs were vertically aligned while the grafts with pendant TPAs were extended parallel to the substrate. The overall design realized high TPA π-stacking along the out-of-plane direction of the substrate in the HTLs, which doubled the efficiency of organic light-emitting diodes compared with linear poly(vinyl triphenylamine)s.