Non-conjugated Polynorbornene Hosts with High Triplet Energy Levels for Solution-processed Narrowband Blue OLEDs
Non-conjugated Polynorbornene Hosts with High Triplet Energy Levels for Solution-processed Narrowband Blue OLEDs
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DOI：
10.1007/s40242-023-3167-1
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发表时间：
2023-09
影响因子：
3.1
通讯作者：
Qiang Li;Liang Chen;Xingdong Wang;Shumeng Wang;Shiyang Shao;Lixiang Wang
中科院分区：
文献类型：
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作者：
Qiang Li;Liang Chen;Xingdong Wang;Shumeng Wang;Shiyang Shao;Lixiang Wang
开发了三种以非共轭聚苯乙烯（PNB）为主链，侧链上含有空穴传输芳胺（咔唑、吖啶和树枝状四吖啶）的聚合物基质（PNB-tBuCz、PNB-Ac和PNB-TAc），用于溶液法制备窄带蓝光有机电致发光器件（OLED）。研究发现，非共轭聚双烯通过中断重复单元的共轭，可以保持3.12-3.20 eV的高三重态能级，使其成为蓝光发光的主体材料。同时，通过增加侧链芳胺从咔唑到吖啶烷和树枝状四吖啶烷的供电子能力，聚合物主体的最高占据分子轨道（HOMO）能级从−5.50 eV提高到−5.11 eV，有利于降低从阳极到发射层的空穴注入势垒。结果表明，采用含树枝状四吖啶烷侧链的聚双烯（PNB-TAc）作为主体，含硼、硒、氮的多重共振热激活延迟荧光发射体作为掺杂剂，溶液处理的OLED显示出有效的窄带蓝色电致发光，其发射峰位于474 nm，半峰全宽为30 nm，最大外量子效率为20.2%，代表了具有窄带蓝光发射的溶液处理OLED的现有技术的器件效率。
Three polymer hosts (namely PNB-tBuCz, PNB-Ac, PNB-TAc) containing non-conjugated polynorbornene (PNB) backbone and hole-transporting arylamine segments (carbazole, acridan and dendritic teracridan) in side chains are developed for solution-processed narrowband blue organic light-emitting diodes (OLEDs). It is found that the non-conjugated polynorbornenes can keep high triplet energy (ET) levels in range of 3.12–3.20 eV by interrupting the conjugation of repeating units, making them capable as host materials for blue emitters. Meanwhile, by increasing the electron-donating capability of side chain arylamine from carbazole to acridan and dendritic teracridan, the highest occupied molecular orbital (HOMO) levels for the polymer hosts are elevated from −5.50 eV to −5.11 eV, beneficial for reducing the hole injection barrier from anode to emissive layer. As a result, solution-processed OLEDs employing polynorbornenes with dendritic teracridan side chain (PNB-TAc) as host and boron, selenium, nitrogen-containing multiple resonance thermally activated delayed fluorescence emitter as dopant reveal efficient narrowband blue electroluminescence with emission peak at 474 nm, full-width at half maximum of 30 nm, together with maximum external quantum efficiency of 20.2%, representing the state-of-the-art device efficiency for solution-processed OLEDs with narrowband blue emission.