Highly Efficient Sky-Blue Fluorescent Organic Light Emitting Diode Based on Mixed Cohost System for Thermally Activated Delayed Fluorescence Emitter (2CzPN)
详细信息 查看全文
- 作者：Jin Won Sun ; Kwon-Hyeon Kim ; Chang-Ki Moon ; Jeong-Hwan Lee ; Jang-Joo Kim
- 刊名：ACS Applied Materials & Interfaces
- 出版年：2016
- 出版时间：April 20, 2016
- 年：2016
- 卷：8
- 期：15
- 页码：9806-9810
- 全文大小：329K
- 年卷期：0
- ISSN：1944-8252
文摘
The mixed cohosts of 1,3-bis(N-carbazolyl)benzene and 2,8-bis(diphenylphosphoryl)dibenzothiophene have been developed for a highly efficient blue fluorescent oragnic light emitting diode (OLED) doped with a thermally activated delayed fluorescence (TADF) emitter [4,5-di (9H-carbazol-9-yl) phthalonitrile (2CzPN)]. We have demonstrated one of the highest external quantum efficiency of 21.8% in blue fluorescent OLEDs, which is identical to the theoretically achievable maximum electroluminescence efficiency using the emitter. Interestingly, the efficiency roll-off is large even under the excellent charge balance in the device and almost the same as the single host based devices, indicating that the efficiency roll-off in 2CzPN based TADF host is related to the material characteristics, such as low reverse intesystem crossing rate rather than charge imbalance.