Carbazole-dendrite-encapsulated electron acceptor core for constructing thermally activated delayed fluorescence emitters used in nondoped solution-processed organic light-emitting diodes
Carbazole-dendrite-encapsulated electron acceptor core for constructing thermally activated delayed fluorescence emitters used in nondoped solution-processed organic light-emitting diodes
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DOI：
10.1016/j.orgel.2017.06.029
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发表时间：
2017-09
影响因子：
3.2
通讯作者：
Jinshan Wang;Jinghong Peng;Wei Yao;Cuifeng Jiang;Chao Liu;Changsen Zhang;He Meng;Rong-hua Liu;Xiaowen Xia;Chuang Yao
中科院分区：
文献类型：
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作者：
Jinshan Wang;Jinghong Peng;Wei Yao;Cuifeng Jiang;Chao Liu;Changsen Zhang;He Meng;Rong-hua Liu;Xiaowen Xia;Chuang Yao
两种荧光发射体，即苯基双(4-(3,3”,6,6”-四叔丁基-9′H-[9,3′:6′,9”-三咔唑]-9′-基)苯基)氧化膦(TPPOCz)和构建了9',9‴'-(磺酰基双(4,1-亚苯基))双(3,3”,6,6”-四叔丁基-9'H-9,3':6',9”-三咔唑)(DBSOCz)。这些化合物发出深蓝色和蓝绿色信号，以三苯基膦氧化物/磺酰二苯作为电子受体核心，以咔唑枝晶作为电子供体封装基团。简单的构建策略使这些发射器功能化，以表现出高热稳定性、合适的最高占据分子轨道/最低未占据分子轨道能级、相对高的光致发光量子产率和良好的成膜能力。使用发射光谱和量子计算来确认 TPPOCz 和 DBSOCz 具有较小的单线态-三线态能量分裂（0.22 和 0.10 eV）。因此，这些荧光发射体表现出显着的热激活延迟荧光特征和较短的延迟荧光寿命。因此，以 DBSOCz 作为非掺杂发射极的溶液加工 OLED 实现了 15.5 cd/A 的最大电流效率和 7.65% 的外量子效率。令人惊讶的是，基于 DBSOCz 的器件在 3000 cd/m2 的高亮度下表现出 4.5% 的超慢电流效率滚降。该值几乎代表了热激活延迟荧光 OLED 中电流效率的最低衰减。
Two fluorescent emitters, namely, phenylbis(4-(3,3″,6,6″-tetra-tert-butyl-9′H-[9,3′:6′,9″-tercarbazol]-9′-yl)phenyl)phosphineoxide (TPPOCz) and 9′,9‴′-(sulfonylbis(4,1-phenylene))bis(3,3″,6,6″-tetra-tert-butyl-9′H-9,3′:6′,9″- tercarbazole) (DBSOCz) are constructed. These compounds emit deep-blue and bluish-green signals and feature triphenylphosphine oxide/sulfonyldibenzene as electron acceptor core and carbazole dendrite as electron donor encapsulation groups. A simple construction strategy functionalizes these emitters to exhibit high thermal stability, suitable highest occupied molecular orbital/lowest unoccupied molecular orbital levels, relatively high photoluminescent quantum yields, and good film-forming capability. Emission spectrum and quantum computation were used to confirm that TPPOCz and DBSOCz possess small singlet–triplet energy splitting (0.22 and 0.10 eV). As a result, these fluorescent emitters exhibit significant thermally activated delayed fluorescence features with a short delayed fluorescence lifetime. Consequently, solution-processed OLEDs featuring DBSOCz as the non-doped emitter achieved a maximum current efficiency of 15.5 cd/A and external quantum efficiency of 7.65%. Surprisingly, the DBSOCz-based device exhibits an ultraslow current efficiency roll-off of 4.5% at a high luminance of 3000 cd/m2. The value represents almost the lowest attenuation of current efficiency in thermally activated delayed fluorescence-based OLEDs.