Ren Bao-Yi, Guo Run-Da, Zhong Dao-Kun, Ou Chang-Jin, Xiong Gang, Zhao Xiang-Hua, Sun Ya-Guang, Jurow Matthew, Kang Jun, Zhao Yi, Li Sheng-Biao, You Li-Xin, Wang Lin-Wang, Liu Yi, Huang Wei
Key Laboratory of Inorganic Molecule-Based Chemistry of Liaoning Province, College of Applied Chemistry, Shenyang University of Chemical Technology , Shenyang 110142, P. R. China.
Key Laboratory for Organic Electronics and Information Displays & Institute of Advanced Materials, Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing University of Posts & Telecommunications , 9 Wenyuan Road, Nanjing 210023, P. R. China.
Inorg Chem. 2017 Jul 17;56(14):8397-8407. doi: 10.1021/acs.inorgchem.7b01034. Epub 2017 Jun 28.
To suppress concentration quenching and to improve charge-carrier injection/transport in the emission layer (EML) of phosphorescent organic light-emitting diodes (PhOLEDs), a facial homoleptic iridium(III) complex emitter with amorphous characteristics was designed and prepared in one step from a multifunctional spiro ligand containing spiro[fluorene-9,9'-xanthene] (SFX) unit. Single-crystal X-ray analysis of the resulting fac-Ir(SFXpy) complex revealed an enlarged Ir···Ir distance and negligible intermolecular π-π interactions between the spiro ligands. The emitter exhibits yellow emission and almost equal energy levels compared to the commercial phosphor iridium(III) bis(4-phenylthieno[3,2-c]pyridinato-N,C')acetylacetonate (PO-01). Dry-processed devices using a common host, 4,4'-bis(N-carbazolyl)-1,1'-biphenyl, and the fac-Ir(SFXpy) emitter at a doping concentration of 15 wt % exhibited a peak performance of 46.2 cd A, 36.3 lm W, and 12.1% for the current efficiency (CE), power efficiency (PE), and external quantum efficiency (EQE), respectively. Compared to control devices using PO-01 as the dopant, the fac-Ir(SFXpy)-based devices remained superior in the doping range between 8 and 15 wt %. The current densities went up with increasing doping concentration at the same driving voltage, while the roll-offs remain relatively low even at high doping levels. The superior performance of the new emitter-based devices was ascribed to key roles of the spiro ligand for suppressing aggregation and assisting charge-carrier injection/transport. Benefiting from the amorphous stability of the emitter, the wet-processed device also exhibited respectful CE, PE, and EQE of 32.2 cd A, 22.1 lm W, and 11.3%, respectively, while the EQE roll-off was as low as 1.7% at the luminance of 1000 cd m. The three-dimensional geometry and binary-conjugation features render SFX the ideal multifunctional module for suppressing concentration quenching, facilitating charge-carrier injection/transport, and improving the amorphous stability of iridium(III)-based phosphorescent emitters.
为了抑制浓度猝灭并改善磷光有机发光二极管（PhOLEDs）发射层（EML）中的电荷载流子注入/传输，从含螺[芴-9,9'-呫吨]（SFX）单元的多功能螺环配体一步设计并制备了具有非晶特性的面式均配铱（III）配合物发光体。所得面式-Ir（SFXpy）配合物的单晶X射线分析表明，螺环配体之间的Ir···Ir距离增大且分子间π-π相互作用可忽略不计。该发光体呈现黄色发射，与商用磷光铱（III）双（4-苯基噻吩并[3,2-c]吡啶-N,C'）乙酰丙酮化物（PO-01）相比，能级几乎相等。使用常见主体4,4'-双（N-咔唑基）-1,1'-联苯和掺杂浓度为15 wt%的面式-Ir（SFXpy）发光体制备的干法器件，电流效率（CE）、功率效率（PE）和外量子效率（EQE）的峰值性能分别为46.2 cd A、36.3 lm W和12.1%。与使用PO-01作为掺杂剂的对照器件相比，基于面式-Ir（SFXpy）的器件在8至15 wt%的掺杂范围内仍表现优异。在相同驱动电压下，电流密度随掺杂浓度的增加而升高，而即使在高掺杂水平下，滚降仍相对较低。基于新型发光体的器件的优异性能归因于螺环配体在抑制聚集和辅助电荷载流子注入/传输方面的关键作用。受益于发光体的非晶稳定性，湿法器件的CE、PE和EQE也分别达到可观的32.2 cd A、22.1 lm W和11.3%，而在1000 cd m的亮度下，EQE滚降低至1.7%。三维几何结构和二元共轭特征使SFX成为抑制浓度猝灭、促进电荷载流子注入/传输以及提高基于铱（III）的磷光发光体非晶稳定性的理想多功能模块。
