1School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384 2Key Laboratory of Display Materials and Photoelectric devices (Ministry of Education), Tianjin 300384 3Tianjin Key Laboratory of Photoelectric Materials and devices, Tianjin 300384
Highly Efficient Simplified Organic Light-Emitting Diodes Utilizing F4-TCNQ as an Anode Buffer Layer
1School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384 2Key Laboratory of Display Materials and Photoelectric devices (Ministry of Education), Tianjin 300384 3Tianjin Key Laboratory of Photoelectric Materials and devices, Tianjin 300384
摘要We demonstrate that the electroluminescent performances of organic light-emitting diodes (OLEDs) are significantly improved by evaporating a thin F4-TCNQ film as an anode buffer layer on the ITO anode. The optimum Alq3−based OLEDs with F4-TCNQ buffer layer exhibit a lower turn-on voltage of 2.6 V, a higher brightness of 39820 cd/m2 at 13 V, and a higher current efficiency of 5.96 cd/A at 6 V, which are obviously superior to those of the conventional device (turn−on voltage of 4.1 V, brightness of 18230 cd/m2 at 13 V, and maximum current efficiency of 2.74 cd/A at 10 V). Furthermore, the buffered devices with F4−TCNQ as the buffer layer could not only increase the efficiency but also simplify the fabrication process compared with the p-doped devices in which F4-TCNQ is doped into β-NPB as p-HTL (3.11 cd/A at 7 V). The reason why the current efficiency of the p-doped devices is lower than that of the buffered devices is analyzed based on the concept of doping, the measurement of absorption and photoluminescence spectra of the organic materials, and the current density-voltage characteristics of the corresponding hole-only devices.
Abstract：We demonstrate that the electroluminescent performances of organic light-emitting diodes (OLEDs) are significantly improved by evaporating a thin F4-TCNQ film as an anode buffer layer on the ITO anode. The optimum Alq3−based OLEDs with F4-TCNQ buffer layer exhibit a lower turn-on voltage of 2.6 V, a higher brightness of 39820 cd/m2 at 13 V, and a higher current efficiency of 5.96 cd/A at 6 V, which are obviously superior to those of the conventional device (turn−on voltage of 4.1 V, brightness of 18230 cd/m2 at 13 V, and maximum current efficiency of 2.74 cd/A at 10 V). Furthermore, the buffered devices with F4−TCNQ as the buffer layer could not only increase the efficiency but also simplify the fabrication process compared with the p-doped devices in which F4-TCNQ is doped into β-NPB as p-HTL (3.11 cd/A at 7 V). The reason why the current efficiency of the p-doped devices is lower than that of the buffered devices is analyzed based on the concept of doping, the measurement of absorption and photoluminescence spectra of the organic materials, and the current density-voltage characteristics of the corresponding hole-only devices.
[1] D'Andrade B W et al 2004 Adv. Mater. 16 1585
[2] Reineke S et al 2009 Nature 459 234
[3] Kamtekar K T et al 2010 Adv. Mater. 22 572
[4] Xie J et al 2006 Chin. Phys. Lett. 23 928
[5] Wang F X et al 2008 Org. Electron. 9 985
[6] Zhang D D et al 2009 Appl. Phys. Lett. 94 223306
[7] Zhang D D et al 2009 Appl. Phys. Lett. 95 263303
[8] Liu Q, Duan L et al 2009 Chin. Phys. Lett. 26 106801
[9] Gao W Y and Kahn A 2001 Appl. Phys. Lett. 79 4040
[10] Huang J S, Pfeiffer M, Werner A, Blochwitz J, Leo K and Liu S Y 2002 Appl. Phys. Lett. 80 139
[11] He G F, Pfeiffer M et al 2004 Appl. Phys. Lett. 85 3911
[12] Baek S H et al 2009 Mol. Cryst. Liq. Cryst. 498 258
[13] Hudson Z M and Wang S N 2009 Acc. Chem. Res. 42 1584
[14] Koch N, Duhm S and Rabe J P 2005 Phys. Rev. Lett. 95 237601
[15] Braun S and Salaneck W R 2007 Chem. Phys. Lett. 438 259
[16] Qi D C, Chen W et al 2007 J. Am. Chem. Soc. 129 8084
[17] Zhou X et al 2001 Appl. Phys. Lett. 78 410
[18] Walzer K, Maennig B, Pfeiffer M and Leo K 2007 Chem. Rev. 107 1233
[19] Mi B X, Gao Z Q, Cheah K W and Chen C H 2009 Appl. Phys. Lett. 94 073507
[20] Pfeiffer M et al 2003 Org. Electron. 4 89
2010, Vol. 27 
