TITLE

Singlet-singlet and singlet-heat annihilations in fluorescence-based organic light-emitting diodes under steady-state high current density

AUTHOR(S)
Nakanotani, Hajime; Sasabe, Hiroyuki; Adachi, Chihaya
PUB. DATE
May 2005
SOURCE
Applied Physics Letters;5/23/2005, Vol. 86 Issue 21, p213506
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
We observed a significant decrease in electroluminescence (EL) in the high-current-density region (J>1 A/cm2) in organic light-emitting diodes (OLEDs). The decreased external quantum efficiency (ηext) in an OLED with a cathode diameter of d=50 μm was in excellent agreement with the singlet–singlet annihilation (SSA) model. In contrast, the decreased ηext in an OLED with a cathode diameter of d=1000 μm coincided well with the singlet-heat annihilation (SHA) model. These results suggest that large OLEDs generate significant Joule heat, which causes additional exciton dissociation in addition to SSA. We also used a very thermally conductive sapphire substrate (46 k/Wm-1 K-1) combined with a small cathode diameter of 50 μm in an OLED to alleviate the ηext roll off characteristics and achieved injection at a much higher current density. With this device configuration, a maximum current density of Jmax=447 A/cm2 was achieved. However, decreased ηext based on SHA was observed in the high current region, indicating that significant Joule heat was generated under a few hundred A/cm2 that induced additional exciton dissociation even when the sapphire substrate was used.
ACCESSION #
17226894

 

Related Articles

  • Tunable and white light-emitting diodes of monolayer fluorinated benzoxazole graft copolymers. S. J. Bai, Emillo; C. C. Wu; Dang, T. D.; Arnold, F. E.; Sakaran, B. // Applied Physics Letters;3/8/2004, Vol. 84 Issue 10, p1656 

    Coil-like graft copolymers of poly(A[sub m]-co-B[sub (1-m)]) containing identical heterocyclic aromatic benzoxazole with trifluoromethyl-ethyl as the backbone and pendants of monohydroxl (A[sub m]) and/or bidecyloxyl (B[sub (1-m)]) on their phenylene ring were studied for luminescence...

  • Highly efficient organic light-emitting diodes from delayed fluorescence. Uoyama, Hiroki; Goushi, Kenichi; Shizu, Katsuyuki; Nomura, Hiroko; Adachi, Chihaya // Nature;12/13/2012, Vol. 492 Issue 7428, p234 

    The inherent flexibility afforded by molecular design has accelerated the development of a wide variety of organic semiconductors over the past two decades. In particular, great advances have been made in the development of materials for organic light-emitting diodes (OLEDs), from early devices...

  • Advanced pump diodes improve laser-system performance. Williamson, Rob // Laser Focus World;Mar2005, Vol. 41 Issue 3, p59 

    This article focuses on advanced pump diodes which improves laser-system performance. The high-power multimode laser diode is the engine behind all types of fiber lasers, diode-pumped solid-state lasers (DPSSs), and high-power fiber amplifiers. This key component efficiently transforms input...

  • Red, Green, and Blue Photoluminescence of Ba2SiO4:M (M = Eu3+, Eu2+, Sr2+) Nanophosphors. Streit, Huayna Cerqueira; Kramer, Jennifer; Suta, Markus; Wickleder, Claudia // Materials (1996-1944);Aug2013, Vol. 6 Issue 8, p3079 

    Divalent europium doped barium orthosilicate is a very important phosphor for the production of light emitting diodes (LEDs), generally associated to the green emission color of micron-sized crystals synthesized by means of solid-state reactions. This work presents the combustion synthesis as an...

  • Pd/InAlN Schottky diode with low reverse current by sulfide treatment. Chen, Z. T.; Fujita, K.; Egawa, T. // Applied Physics Letters;10/31/2011, Vol. 99 Issue 18, p183504 

    The authors report the effect of sulfide treatment on electrical characteristic of Pd/InAlN Schottky diode. Quantitative analysis considering different current-transport mechanisms revealed that the sulfide treatment not only significantly reduced leakage current but also almost completely...

  • A theoretical and experimental investigation of light extraction from polymer light-emitting diodes. Ziebarth, Jonathan M.; McGehee, Michael D. // Journal of Applied Physics;3/15/2005, Vol. 97 Issue 6, p064502 

    Using numerical modeling techniques we predict the emission into air, substrate, polymer/indium tin oxide (ITO), and surface-plasmon modes of a polymer light-emitting diode. The results give good insight into the possible efficiency increases that can be expected for various light extraction...

  • Inside a surge protector. Willcox, James K. // Sound & Vision;Jul/Aug2007, Vol. 72 Issue 6, p80 

    The article features the interior parts of the S20 power conditioner and battery backup surge protector from APC AV. The most prominent feature of the S20 is a large vacuum-fluorescent readout, surrounded by an elliptical array of light emitting diodes (LEDs) and buttons. Its alternative current...

  • The Study of LED Linear Dimming with Hysteresis Current Driver and Peak Current Detection Driver. Gong-Bei Chen; Ton-Churo Huang; Yih-Guang Leu; Kuo-Teng Hung // Applied Mechanics & Materials;2014, Issue 538, p265 

    This paper studies the characteristics of LED linear dimming using Peak Current Control (PCC) and Hysteretic Current Control (HCC) methods. It presents the PCC and HCC circuit architectures,discusses their strength and weakness with various architectures and experimently compares their dimming...

  • Highly efficient p-i-n white organic light emitting devices with tandem structure. Ho, Meng-Huan; Chen, Teng-Ming; Yeh, Pu-Cheng; Hwang, Shiao-Wen; Chen, Chin H. // Applied Physics Letters;12/3/2007, Vol. 91 Issue 23, p233507 

    Highly efficient tandem p-i-n white organic light emitting devices have been fabricated. Utilizing an optical transparent bilayer with doped organic p-n junction that consists of 4,7-diphenyl-1,10-phenanthroline: 2% cesium carbonate...

Share

Read the Article

Courtesy of THE LIBRARY OF VIRGINIA

Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics