Selectively Controlled Orientational Order in Linear-Shaped Thermally Activated Delayed Fluorescent Dopants

详细信息    查看全文

• 作者：Takeshi Komino ; Hiroyuki Tanaka ; Chihaya Adachi
• 刊名：Chemistry of Materials
• 出版年：2014
• 出版时间：June 24, 2014
• 年：2014
• 卷：26
• 期：12
• 页码：3665-3671
• 全文大小：390K
• ISSN：1520-5002

文摘

The orientational order of a linear-shaped thermally activated delayed fluorescent dopant 10-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-10H-phenoxazine (PXZ-TRZ) was selectively controlled in a randomly oriented host matrix composed of 3,3-di(9H-carbazol-9-yl)biphenyl (mCBP) by varying the temperature during deposition of the thin films. Although the molecular orientation of mCBP was random at deposition temperatures ranging from 200 to 300 K (orientational disorder), PXZ-TRZ molecules oriented horizontal to the substrate in this temperature range (high orientational order). This indicates that the orientational order was dominated by the kinetic behavior of PXZ-TRZ at the film surface rather than by randomization caused by aggregation of PXZ-TRZ and mCBP molecules. Using an orientation-controlled 6 wt % PXZ-TRZ:mCBP film as an emitting layer, we fabricated organic light-emitting diodes (OLEDs). The horizontal orientation of the dopants enhanced the external electroluminescence quantum efficiency of the OLED by 24% compared with that of the corresponding OLED with slightly vertical orientation. An optical simulation found that the enhancement originates mainly from the improvement of the light out-coupling efficiency.