Systematic investigation of transparent organic light-emitting diodes depending on top metal electrode thickness

Abstract We investigate the optical characteristics of transparent organic light-emitting diodes (TOLEDs) with thickness variation of the top metal electrode. We find that the thickness variation of the top cathode shows a different influence on the bottom and top side emissions, respectively. The overall efficiency which is the sum of the bottom and top emissions can be enhanced up to 17.7% of external quantum efficiency (EQE) and 25.1 lm/W of power efficiency (PE) at a driving current density of 15 mA/cm2. Furthermore, we carefully investigate the angular distribution of the bottom and top side emissions separately with a spectrogoniometer. We find that both considerably differ from a Lambertian assumption and exhibit opposite trends, depending on the top metal cathode thickness.

[1]  Xiang Zhou,et al.  Low-voltage inverted transparent vacuum deposited organic light-emitting diodes using electrical doping , 2002 .

[2]  Martin Pfeiffer,et al.  Highly efficient top emitting organic light-emitting diodes with organic outcoupling enhancement layers , 2006 .

[3]  K. Leo,et al.  High-efficiency monochrome organic light emitting diodes employing enhanced microcavities , 2008 .

[4]  K. Leo,et al.  Optimized efficiency and angular emission characteristics of white top-emitting organic electroluminescent diodes , 2009 .

[5]  W. Barnes,et al.  Light outcoupling efficiency of top-emitting organic light-emitting diodes , 2004 .

[6]  Inverted transparent multi-layered vacuum deposited organic light-emitting diodes with electrically doped carrier transport layers and coumarin doped emissive layer , 2003 .

[7]  S. Forrest,et al.  Highly efficient phosphorescent emission from organic electroluminescent devices , 1998, Nature.

[8]  Gregor Schwartz,et al.  White organic light-emitting diodes with fluorescent tube efficiency , 2009, Nature.

[9]  Jan Birnstock,et al.  High-efficiency and low-voltage p‐i‐n electrophosphorescent organic light-emitting diodes with double-emission layers , 2004 .

[10]  Karsten Walzer,et al.  Performance improvement of top-emitting organic light-emitting diodes by an organic capping layer: An experimental study , 2006 .

[11]  Linghai Xie,et al.  Recent Developments in Top‐Emitting Organic Light‐Emitting Diodes , 2010, Advanced materials.

[12]  Chul Woong Joo,et al.  Transparent organic light emitting diodes using a multilayer oxide as a low resistance transparent cathode , 2008 .

[13]  Ho Kyoon Chung,et al.  High efficiency and low power consumption in active matrix organic light emitting diodes , 2003 .

[14]  Wei Huang,et al.  Blue top-emitting organic light-emitting devices using a 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline outcoupling layer , 2008 .

[15]  M. Toerker,et al.  Origin of damages in OLED from Al top electrode deposition by DC magnetron sputtering , 2010 .

[16]  Karl Leo,et al.  Influence of organic capping layers on the performance of transparent organic light-emitting diodes. , 2011, Optics letters.

[17]  William L. Barnes,et al.  Surface plasmon–polariton mediated emission of light from top-emitting organic light-emitting diode type structures , 2007 .

[18]  Xiang Zhou,et al.  Doped organic semiconductors: Physics and application in light emitting diodes , 2003 .

[19]  Po-Chiang Chen,et al.  Transparent active matrix organic light-emitting diode displays driven by nanowire transistor circuitry. , 2008, Nano letters.

[20]  Karl Leo,et al.  Outcoupling efficiency in small-molecule OLEDs: from theory to experiment , 2010, OPTO.

[21]  Karl Leo,et al.  Top-emitting organic light-emitting diodes: Influence of cavity design , 2010 .