Browsing by Author "Renaud, C."

Now showing 1 - 3 of 3

Investigation of defects in organic semiconductors by charge based Deep Level Transient Spectroscopy (Q-DLTS)
(2009)
Nguyen, T. P.
;
Renaud, C.
;
Le Rendu, P.
;
Yang, S. H.
;
應用化學系
We report the results of measurements of traps in light emitting devices using a new derivative of poly(phenylene vinylene) (PPV) as an active material by the charge based Deep Level Transient Spectroscopy (Q-DLTS) technique. Diodes of structure Indium Tin Oxide (ITO)/PEDOT:PSS/poly(2-ethylhexyl)surfanyl-5- methoxy phenylene vinylene (MEH-S-PPV)/M with M = Al and M = Ca/Al were investigated by measurements of current-voltage-luminance characteristics. From analysis of these characteristics, evidence of charge trapping in devices was demonstrated. The trap parameters were then determined from Q-DLTS measurements, which were carried out on the samples as a function of the charging time, the applied voltage and the temperature. Five trap levels of activation energy in the range [0.-0.6 eV] and of density of order of 10(17) cm(-3) were identified in diodes with Ca/Al cathode. Electron (one level) and hole (four levels) traps were then clearly distinguished by performing measurements in hole-only devices. Trapping processes are discussed and tentatively proposed to performance of the light emitting diodes studied. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Study of trap states in polyfluorene based devices by using TSC technique
(2008-08-30)
Renaud, C.
;
Huang, C. H.
;
Lee, C. W.
;
Le Rendu, P.
;
Nguyen, T. P.
The trap states in poly(9,9-dihexylfluorene-co-N,N-di(9,9-dihexyl-2-fluorenyl)-N-phenylamine) (PF-N-Ph) based light emitting diodes have been investigated by using the thermally stimulated current (TSC) technique in the temperature range of 90-320 K. The studied structure consisted of indium-tin-oxide/polyethylene-dioxythiophene: polystyrene-sulfonate/PF-N-Ph/Al. Four traps centers denoted as A, B, C, and D trap types have been identified with densities in the range of 10(16)-10(17) cm(-3). Study of the dependence of TSC characteristics on the device polarity suggested that the A, C and D type traps are electron traps while the B type traps are hole traps. They can be described by Gaussian distributions centered on mean trap levels. (c) 2008 Elsevier B.V. All rights reserved.
Study of traps in polydiacetylene based devices using TSC technique
(2006-12-01)
Renaud, C.
;
Huang, C. H.
;
Zemmouri, M.
;
Le Rendu, P.
;
Nguyen, T. P.
Trap parameters in poly(1-(3,4-difluorophenyl)-2-(4-pentylcyclohexylphenyl)acetylene) (PDPA-2F) based devices have been investigated by using the thermally stimulated current (TSC) technique. The device structure is ITO-PEDOT-(PDPA-2F)-M, where M stands for the cathode metal (Al, Ca/Al, and Au). The results reveal at least three TSC peaks in devices denoted as peaks A, B and C. Comparing trap parameters in ITO-PEDOT-(PDPA-2F)-Au hole-only device and ITO-PEDOT-(PDPA-2F)-Ca Al (Al) bipolar devices, we assigned A and B trap types to hole-like traps and C type traps to electron-like traps. The trap densities are in the range of 10(15)-10(17) cm(-3) and the trap levels are 0.12 eV (A type traps), 0.36 eV (B type traps), and 0.25 eV (C type traps).