Absorptive and conductive cavity cathode with silver nanoparticles for low-reflection organic light-emitting devices

We have successfully fabricated a low-reflection organic light-emitting diode (LR-OLED) by replacing the highly reflective Al cathode of a conventional OLED with a Fabry?P?rot (FP) cavity cathode, which is simultaneously responsible for absorption, plasmonic absorption and destructive interference. The FP cavity cathode consisted of a front semi-transparent double thin metal layer (Al/Ag), an inserted organometallic black layer (BL) in the middle and a highly reflective Al mirror. The organometallic BL contained a high-mobility electron transport and broadband absorptive organic matrix, N,N'-bis(2,6-diisopropylphenyl)-1,7-bis(4-methoxy-phenyl)perylene-3,4,9,10-tetracarboxydiimide (MPPDI), and Ag-nanoparticle (NP) dopants which contributed not only to the plasmonic absorption but also to the metallic conductivity. By adjusting the thickness and Ag-NP concentration of the organometallic BL, one can optimize the destructive interference cavity effect. LR-OLEDs fabricated using the aforementioned characteristics of the Ag-NP yielded superior electrical performance and low reflection across almost the entire visible spectrum. With the exemption of surface reflection (air/glass ~4%), a lowest reflection of 0% near 750?nm and an average reflection of 1.39% for the entire visible spectrum were obtained for a LR-OLED with a 65?nm organometallic BL (mixing ratio of MPPDI?:?Ag = 10?:?1). With the additional structural cavity cathode, the LR-OLEDs nonetheless exhibited similar electrical performances and continuous operational lifetimes to those of control devices with a traditional highly reflective Al cathode.

[1]  A. Krasnov,et al.  High-contrast organic light-emitting diodes on flexible substrates , 2002 .

[2]  Yanfeng Dai,et al.  High efficiency fluorescent white organic light-emitting diodes with red, green and blue separately monochromatic emission layers , 2009 .

[3]  Carsten Sönnichsen,et al.  Plasmon resonances in large noble-metal clusters , 2002 .

[4]  Low reflection and photo-sensitive organic light-emitting device with perylene diimide and double-metal structure , 2009 .

[5]  J. Murphy,et al.  Gaussian-beam mode analysis of reflection and transmission in multilayer dielectrics. , 2008, Journal of the Optical Society of America. A, Optics, image science, and vision.

[6]  Cho SungYong,et al.  쟕emperature effect of Si-doped MgO protective layer on discharge characteristics of an AC-PDP , 2009 .

[7]  Zhenghong Lu,et al.  Metal–organic–metal cathode for high-contrast organic light-emitting diodes , 2004 .

[8]  White organic light-emitting devices with Sm:Ag black cathode. , 2006, Optics express.

[9]  M. Leung,et al.  Photophysical and electrochemical properties of 1,7-diaryl-substituted perylene diimides. , 2005, The Journal of organic chemistry.

[10]  Galileo Sarasqueta,et al.  Organic/inorganic nanocomposites for high-dielectric-constant materials , 2008 .

[11]  Hany Aziz,et al.  Reduced reflectance cathode for organic light-emitting devices using metalorganic mixtures , 2003 .

[12]  C.-H. Chen,et al.  Recent progress of molecular organic electroluminescent materials and devices , 2002 .

[13]  Shin‐Tson Wu,et al.  High ambient-contrast-ratio display using tandem reflective liquid crystal display and organic light-emitting device. , 2005, Optics express.

[14]  Metal-induced photoluminescence quenching in thin organic films originating from noncontact energy transfer between single molecule and atom , 2007 .

[15]  Shui-Tong Lee,et al.  Contrast improvement of organic light-emitting devices with Sm:Ag cathode , 2006 .

[16]  Chi-Chih Liao,et al.  High contrast ratio organic light-emitting devices based on CuPC as electron transport material , 2004 .

[17]  Shin‐Tson Wu,et al.  Transflective device with a transparent organic light‐emitting diode and a reflective liquid‐crystal device , 2009 .

[18]  Kyung Cheol Choi,et al.  Surface plasmon-enhanced energy transfer in an organic light-emitting device structure. , 2009, Optics express.

[19]  C. Tang,et al.  Organic Electroluminescent Diodes , 1987 .

[20]  Christophe Py,et al.  Design of high-contrast OLEDs with microcavity effect. , 2008, Optics express.

[21]  T. Chu,et al.  Thickness dependence of the trap states in organic thin film of N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl) benzidine , 2007 .

[22]  J A Dobrowolski,et al.  Optical interference, contrast-enhanced electroluminescent device. , 1992, Applied optics.

[23]  Subhasis Ghosh,et al.  Thickness dependence of space charge limited current and injection limited current in organic molecular semiconductors , 2008 .

[24]  Energy-recycling pixel for active-matrix organic light-emitting diode display , 2007 .

[25]  Tien-Lung Chiu,et al.  Optical and electrical characteristics of Ag-doped perylene diimide derivative , 2009 .