TY - JOUR
T1 - Influence of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) in polymer LEDs
AU - Brewer, P. J.
AU - Huang, J.
AU - Lane, P. A.
AU - DeMello, A. J.
AU - Bradley, D. D.C.
AU - DeMello, J. C.
N1 - Generated from Scopus record by KAUST IRTS on 2019-11-27
PY - 2006/9/15
Y1 - 2006/9/15
N2 - We investigate the influence of poly(3,4-ethylenedioxythiophene)- poly(styrenesulfonate) (PEDOT:PSS) on the optoelectronic properties of polymer light-emitting diodes containing poly(9,9-dioctylfluorene) (PFO). Electromodulation and IV luminance measurements are reported for a series of devices with bare indium tin oxide (ITO) or PEDOT:PSS-coated ITO anodes and Ba or Al cathodes. The ITO/PFO/Al, ITO/PFO/Ba, and ITO/PEDOT:PSS/PFO/Al devices all exhibit conventional field-induced electromodulation behavior, in both forward and reverse bias, consistent with the Stark effect (SE). The ITO/PEDOT:PSS/PFO/Ba devices by contrast exhibit conventional behavior only for applied biases below the flat-band voltage; at higher biases, the field-induced SE features vanish and are replaced by anomalous charge-induced electromodulation features. This anomalous behavior is observed only when PEDOT:PSS is used in conjunction with a strongly electron-injecting cathode such as Ba, and is attributed to the presence of trapped electrons at the PEDOT:PSS-emitter interface, which screen the electric field from the bulk of the device. The enhanced field at the interface increases the rate of field-assisted hole injection into the highest occupied molecular orbital (HOMO) of the PFO, resulting in lower drive voltages and increased electroluminescence efficiencies. © 2006 The American Physical Society.
AB - We investigate the influence of poly(3,4-ethylenedioxythiophene)- poly(styrenesulfonate) (PEDOT:PSS) on the optoelectronic properties of polymer light-emitting diodes containing poly(9,9-dioctylfluorene) (PFO). Electromodulation and IV luminance measurements are reported for a series of devices with bare indium tin oxide (ITO) or PEDOT:PSS-coated ITO anodes and Ba or Al cathodes. The ITO/PFO/Al, ITO/PFO/Ba, and ITO/PEDOT:PSS/PFO/Al devices all exhibit conventional field-induced electromodulation behavior, in both forward and reverse bias, consistent with the Stark effect (SE). The ITO/PEDOT:PSS/PFO/Ba devices by contrast exhibit conventional behavior only for applied biases below the flat-band voltage; at higher biases, the field-induced SE features vanish and are replaced by anomalous charge-induced electromodulation features. This anomalous behavior is observed only when PEDOT:PSS is used in conjunction with a strongly electron-injecting cathode such as Ba, and is attributed to the presence of trapped electrons at the PEDOT:PSS-emitter interface, which screen the electric field from the bulk of the device. The enhanced field at the interface increases the rate of field-assisted hole injection into the highest occupied molecular orbital (HOMO) of the PFO, resulting in lower drive voltages and increased electroluminescence efficiencies. © 2006 The American Physical Society.
UR - https://link.aps.org/doi/10.1103/PhysRevB.74.115202
UR - http://www.scopus.com/inward/record.url?scp=33748486677&partnerID=8YFLogxK
U2 - 10.1103/PhysRevB.74.115202
DO - 10.1103/PhysRevB.74.115202
M3 - Article
SN - 1098-0121
VL - 74
JO - Physical Review B - Condensed Matter and Materials Physics
JF - Physical Review B - Condensed Matter and Materials Physics
IS - 11
ER -