Effect of different solvents on the performance of organic light-emitting device based on red-fluorescent ACY dye by spin coating method

A small-molecular red-fluorescent dye of [7-diethylamino-3-(2-thienyl)chronmen-2-ylidene]-2,2-dicyanoviny-lamine (ACY) has been blended into blue-emitting poly(N-vinylcarbazole) (PVK) by using different solvents of chloroform and 1,2-dichloroethane. Photoluminescence characteristic of solvent effects were investigated mainly from the aspect of solvent polarity. To demonstrate the solvent effects in organic light emitting devices (OLEDs), devices with a structure of indium-tin-oxide (ITO)/PVK: ACY (x wt %)/tris(8-quinolinolato) aluminum (Alq3)/Mg: Ag were fabricated, in which the weight doping ratios are x = 0.3, 0.5 and 0.7. Using spin coating method, a blending system of PVK: ACY is dissolved in both chloroform and 1,2-dichloroethane with various doping concentrations. As a result, by choosing chloroform as solvent, a high electroluminescent (EL) performance device with a maximum luminance of 7698 cd/m2 at a driving voltage of 15.5 V was obtained, with a concentration proportion of PVK: ACY at 1000: 7. In the EL spectra of the OLEDs, red and green fluorescence of ACY and Alq3 were detected. It was found that by using 1,2-dichloroethane as a solvent, fluorescent quenching emerged with the enhancement of doping concentration. Energy transfer and Alq3 cations quencher theories were used to discuss different solvent effects on OLEDs.

[1]  Ullrich Mitschke,et al.  The electroluminescence of organic materials , 2000 .

[3]  Joseph R. Lakowicz,et al.  Principles of Fluorescence Spectroscopy, Third Edition , 2008 .

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

[5]  Nasser N Peyghambarian,et al.  Application of Screen Printing in the Fabrication of Organic Light‐Emitting Devices , 2000 .

[6]  D Murphy,et al.  Highly phosphorescent bis-cyclometalated iridium complexes: synthesis, photophysical characterization, and use in organic light emitting diodes. , 2001, Journal of the American Chemical Society.

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

[8]  Shizuo Tokito,et al.  Improvement of organic electroluminescent device performance by in situ plasma treatment of indium–tin-oxide surface , 2000 .

[9]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[10]  Junsheng Yu,et al.  A New Class of High-Performance Red-Fluorescent Dyes for Organic Electroluminescent Devices, [7-Diethylamino-3-(2-thienyl)chromen-2-ylidene]-2,2-dicyanovinylamine and {10-(2-Thienyl)-2,3,6,7-tetrahydro-1H,5H-chromeno[8,7,6-ij]quinolizin-11-ylidene}-2,2-dicyanovinylamine , 2002 .

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

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

[13]  Satoshi Hoshino,et al.  Effects of doping dyes on the electroluminescent characteristics of multilayer organic light‐emitting diodes , 1996 .

[14]  Stephen R. Forrest,et al.  Direct patterning of organic light-emitting devices by organic-vapor jet printing , 2005 .