TY - GEN
T1 - Dynamics of space charge distributions in side-chain PPV LEDs
AU - Michelotti, F.
AU - Bussi, S.
AU - Dominici, L.
AU - Bertolotti, M.
AU - Bao, Z.
AU - Whitelegg, S.
AU - Lane, P. A.
AU - Bradley, D. D.C.
N1 - Generated from Scopus record by KAUST IRTS on 2019-11-27
PY - 2001/10/22
Y1 - 2001/10/22
N2 - A single wavelength electro-optical reflection technique was used to study the creation of space charge distributions (SCDs) in an Al/PPV/ITO LED by monitoring the third order NLO response of the electro-luminescent layer, at a wavelength far from the main absorption band (λ=632.8nm). The polymer is a PPV derivative with oxidiazole groups grafted as side chains. The measurements show the presence of SCD given by the sum of a static contribution close to the ITO, and of a slowly changing and bias dependent one due to mobile charges injection. Taking into account Debye-Hückel screening in the polymer, we estimate the density of the fixed charges to be ρ0 = 1.5 × 1024m-3, for a uniform distribution in a 110nm thick layer. The dynamics of the mobile charges was investigated by time-dependent measurements. The samples were biased at a voltage Vb for a time interval and the time dependence of the signal was studied after switching off Vb. The measurements were performed for several temperatures between 60 and 110°C, indicating complex dynamics of the signal. Measurements performed at low temperature (88K) show the features of dispersive transport. The dynamic measurements were investigated by the electro-absorption technique also, with wavelengths laying in the main absorption band of PPV. © 2001 Elsevier Science B.V. All rights reserved.
AB - A single wavelength electro-optical reflection technique was used to study the creation of space charge distributions (SCDs) in an Al/PPV/ITO LED by monitoring the third order NLO response of the electro-luminescent layer, at a wavelength far from the main absorption band (λ=632.8nm). The polymer is a PPV derivative with oxidiazole groups grafted as side chains. The measurements show the presence of SCD given by the sum of a static contribution close to the ITO, and of a slowly changing and bias dependent one due to mobile charges injection. Taking into account Debye-Hückel screening in the polymer, we estimate the density of the fixed charges to be ρ0 = 1.5 × 1024m-3, for a uniform distribution in a 110nm thick layer. The dynamics of the mobile charges was investigated by time-dependent measurements. The samples were biased at a voltage Vb for a time interval and the time dependence of the signal was studied after switching off Vb. The measurements were performed for several temperatures between 60 and 110°C, indicating complex dynamics of the signal. Measurements performed at low temperature (88K) show the features of dispersive transport. The dynamic measurements were investigated by the electro-absorption technique also, with wavelengths laying in the main absorption band of PPV. © 2001 Elsevier Science B.V. All rights reserved.
UR - https://linkinghub.elsevier.com/retrieve/pii/S0379677901004192
UR - http://www.scopus.com/inward/record.url?scp=0035935376&partnerID=8YFLogxK
U2 - 10.1016/S0379-6779(01)00419-2
DO - 10.1016/S0379-6779(01)00419-2
M3 - Conference contribution
BT - Synthetic Metals
ER -