Solution-Processed Small Molecules As Mixed Host for Highly Efficient Blue and White Phosphorescent Organic Light-Emitting Diodes

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• 作者：Qiang Fu ; Jiangshan Chen ; Changsheng Shi ; Dongge Ma
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2012
• 出版时间：December 26, 2012
• 年：2012
• 卷：4
• 期：12
• 页码：6579-6586
• 全文大小：445K
• 年卷期：v.4,no.12(December 26, 2012)
• ISSN：1944-8252

文摘

The widely used hole-transporting host 4,4鈥?4鈥?tris(N-carbazolyl)-triphenylamine (TCTA) blended with either a hole-transporting or an electron-transporting small-molecule material as a mixed-host was investigated in the phosphorescent organic light-emitting diodes (OLEDs) fabricated by the low-cost solution-process. The performance of the solution-processed OLEDs was found to be very sensitive to the composition of the mixed-host systems. The incorporation of the hole-transporting 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC) into TCTA as the mixed-host was demonstrated to greatly reduce the driving voltage and thus enhance the efficiency due to the improvement of hole injection and transport. On the basis of the mixed-host of TCTA:TAPC, we successfully fabricated low driving voltage and high efficiency blue and white phosphorescent OLEDs. A maximum forward viewing current efficiency of 32.0 cd/A and power efficiency of 25.9 lm/W were obtained in the optimized mixed-host blue OLED, which remained at 29.6 cd/A and 19.1 lm/W at the luminance of 1000 cd/m² with a driving voltage as low as 4.9 V. The maximum efficiencies of 37.1 cd/A and 32.1 lm/W were achieved in a single emissive layer white OLED based on the TCTA:TAPC mixed-host. Even at 1000 cd/m², the efficiencies still reach 34.2 cd/A and 23.3 lm/W and the driving voltage is only 4.6 V, which is comparable to those reported from the state-of-the-art vacuum-evaporation deposited white OLEDs.

Keywords:

solution-processed; small molecules; mixed-host; phosphorescence; blue and white OLEDs