TY - JOUR
T1 - Improved efficiency of organic light-emitting diodes using CoPc buffer layer
AU - Kao, Po Ching
AU - Chu, Sheng Yuan
AU - You, Zong Xian
AU - Liou, S. J.
AU - Chuang, Chan An
N1 - Funding Information:
This work was supported by Ministry of Economic Affairs of the Republic of China (No. 91-EC-17-A-07-S1-0018) and Micro-Nanotechnology Research Center of the NCKU.
PY - 2006/3/1
Y1 - 2006/3/1
N2 - In this paper, the remarkable improvements in turn-on voltage and luminance have been demonstrated in an organic light-emitting diode (OLED) using cobalt phthalocyanine (CoPc) layer as a hole injection layer (HIL) in a device structure of ITO/CoPc/NPB (60 nm)/Alq3 (75 nm)/LiF (1 nm)/Al (200 nm). The J-V, L-V and ηp-V characteristics were measured at room temperature with a thickness variation of CoPc layer. The improvement of the luminance intensity by a factor of more than two has been obtained and the turn-on voltage at 1 cd/m2 decreased about 1 V with the CoPc layer. We propose that such an improvement is mainly due to the relative energy level of the highest-occupied molecular orbital (HOMO) band between that of the NPB hole transport layer (HTL) and the Fermi level of ITO anode, leading to enhance the hole injection from the ITO to organic layer.
AB - In this paper, the remarkable improvements in turn-on voltage and luminance have been demonstrated in an organic light-emitting diode (OLED) using cobalt phthalocyanine (CoPc) layer as a hole injection layer (HIL) in a device structure of ITO/CoPc/NPB (60 nm)/Alq3 (75 nm)/LiF (1 nm)/Al (200 nm). The J-V, L-V and ηp-V characteristics were measured at room temperature with a thickness variation of CoPc layer. The improvement of the luminance intensity by a factor of more than two has been obtained and the turn-on voltage at 1 cd/m2 decreased about 1 V with the CoPc layer. We propose that such an improvement is mainly due to the relative energy level of the highest-occupied molecular orbital (HOMO) band between that of the NPB hole transport layer (HTL) and the Fermi level of ITO anode, leading to enhance the hole injection from the ITO to organic layer.
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U2 - 10.1016/j.tsf.2005.07.120
DO - 10.1016/j.tsf.2005.07.120
M3 - Conference article
AN - SCOPUS:30944458418
SN - 0040-6090
VL - 498
SP - 249
EP - 253
JO - Thin Solid Films
JF - Thin Solid Films
IS - 1-2
T2 - Proceedings of the Third Asian Conference on Chemical Vapor Deposition (Third Asian-CVD), Third Asian CVD
Y2 - 12 November 2004 through 14 November 2004
ER -