Efficiency improvement of yellow organic light-emitting devices by using mixed hole transporting layer

Sujie Chen; Junsheng Yu; Wen Wen; Yadong Jiang

doi:10.1117/12.867248

22 October 2010 Efficiency improvement of yellow organic light-emitting devices by using mixed hole transporting layer

Sujie Chen, Junsheng Yu, Wen Wen, Yadong Jiang

Proceedings Volume 7658, 5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optoelectronic Materials and Devices for Detector, Imager, Display, and Energy Conversion Technology; 76583Z (2010) https://doi.org/10.1117/12.867248
Event: 5th International Symposium on Advanced Optical Manufacturing and Testing Technologies, 2010, Dalian, China

Abstract

Organic light-emitting devices (OLEDs) with a novel metal iridium complex of bis[2-(4-tertbutylphenyl) benzothiazolato-N,C²'] iridium (acetylacetonate) [(t-bt)₂Ir(acac)] doping into a carbazole-based material 4,4'-bis[N-1-napthyl-N-phenyl-amino]biphenyl (CBP) as light-emitting layer (ETL) were fabricated. The optimum doping concentration of (t-bt)₂Ir(acac) phosphor was 8 wt%. The maximum power efficiency (η_p) of the OLED was 8 lm/W. Furthermore, to improve the balance of charge carriers and enhance the η_p of the device, a doping system consisted of NPB hole transporting material and CBP host material with a concentration proportion of 1:3 was employed as the mixed hole transporting layer. OLEDs with a structure of indium-tin oxide (ITO)/N,N'-bis-(1-naphthyl)-N,N'- biphenyl-1,1'-biphenyl-4,4'-diamine (NPB):CBP(1:3)/CBP:(t-bt)₂Ir(acac)/2, 9-dimethyl-4, 7-diphenyl-phenanthroline (BCP)/Mg:Ag were fabricated. The results showed that current density was decreased and the maximum η_p of the device was 10.6 lm/W. Compared with the conventional device with NPB as hole transporting layer, the improved maximum η_p of the device with mixed hole transporting layer was increased 32.5 %. This is attributed to the reduction of hole injection amount and transporting mobility by doping material CBP in hole transporting layer, which significant enhances charge carrier balance and electron-hole recombination probability.

Citation Download Citation

Sujie Chen, Junsheng Yu, Wen Wen, and Yadong Jiang "Efficiency improvement of yellow organic light-emitting devices by using mixed hole transporting layer", Proc. SPIE 7658, 5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optoelectronic Materials and Devices for Detector, Imager, Display, and Energy Conversion Technology, 76583Z (22 October 2010); https://doi.org/10.1117/12.867248

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