Nanosecond transients in the electroluminescence from multilayer blue organic light-emitting devices based on 4,4{sup '}-bis(2,2{sup '}diphenyl vinyl)-1,1{sup '}-biphenyl

Journal Article · Mon Mar 20 04:00:00 EST 2000 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.126076· OSTI ID:20215685

Savvate'ev, V ^[1]; Friedl, J H ^[1]; Zou, L ^[1]; Shinar, J ^[1]; Christensen, K ^[2]; Oldham, W ^[3]; Rothberg, L J ^[3]; Chen-Esterlit, Z ^[4]; Kopelman, R ^[4]

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1. Ames Laboratory-USDOE and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011-3020 (United States)
2. Department of Microbiology and Immunology, School of Medicine, University of Michigan, Ann Arbor, Michigan 48109-0620 (United States)
3. Department of Chemistry, University of Rochester, Rochester, New York 14627 (United States)
4. Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055 (United States)

Nanosecond electroluminescence (EL) overshoots observed when multilayer blue 4,4{sup '}-bis(2,2{sup '}-diphenyl vinyl)-1,1{sup '}-biphenyl (DPVBi)-based organic light-emitting devices (OLEDs) are excited by rectangular voltage pulses are described. The overshoots occur at the voltage turn-off and exceed the cw brightness by up to an order of magnitude. Time-resolved images of the OLEDs demonstrate that the emission from most of the sample surface decays with a single time constant {tau}{sub 1}=13{+-}3 ns. This decay is attributed to recombination of charges which accumulate at the interface of the electron and hole transporting layers, possibly at intrinsic trapping sites. In areas of increased electron injection and EL, such as cathode edges and morphological defects, a second slower decay time 20 ns<{tau}{sub 2}<1 {mu}s is observed, apparently due to release of carriers from localized trap states in the organic/cathode interface. Only marginal variations in {tau}{sub 1} are found between bright and dim areas of the devices. At a bias of 10 V, the amplitude of the overshoot is found to peak at a pulse duration of {approx}20 {mu}s. Its behavior is believed to result from increased quenching of singlet excitons by the accumulated charges. (c) 2000 American Institute of Physics.

• OSTI ID: 20215685
• Journal Information: Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 12 Vol. 76; ISSN APPLAB; ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
74 ATOMIC AND MOLECULAR PHYSICS
ELECTROLUMINESCENCE
EXPERIMENTAL DATA
LAYERS
LIGHT EMITTING DIODES
ORGANIC SEMICONDUCTORS
TRANSIENTS
VISIBLE SPECTRA