TY - JOUR
T1 - Small molecule chemisorption on indium - Tin oxide surfaces
T2 - Enhancing probe molecule electron-transfer rates and the performance of organic light-emitting diodes
AU - Carter, Chet
AU - Brumbach, Michael
AU - Donley, Carrie
AU - Hreha, Richard D.
AU - Marder, Seth R.
AU - Domercq, Benoit
AU - Yoo, Seunghyup
AU - Kippelen, Bernard
AU - Armstrong, Neal R.
PY - 2006/12/21
Y1 - 2006/12/21
N2 - Indium - tin oxide (ITO) surfaces have been modified by chemisorption of carboxylic acid functionalized small molecules: ferrocene dicarboxylic acid (1), 3-thiophene acetic acid (2), and 6-{4-[{4′-[[4-(5-carboxy-pentyloxy)- phenyl]-(4-methoxy-phenyl)-amino]-biphenyl-4-yl}-(4-methoxy-phenyl)-amino] -phenoxy}-hexanoic acid (p-OMe)2-TPD-(C5-COOH) 2) (3). Voltammetrically determined surface coverages of 1-3 increased in two stages, the first stage completing in minutes, the latter stage taking several hours. Electron-transfer rate coefficients, kS, for the probe molecule ferrocene in acetonitrile likewise increased in two stages with increasing surface coverages of 1, 2, and 3. Fourier transform infrared spectroscopy of In2O3 powders, exposed for long periods to ethanol solutions of each modifier, confirmed the formation of indium oxalate-like surface species. X-ray photoelectron spectroscopy of carboxy-terminated alkanethiol-modified gold surfaces, exposed to these same In2O3(powder)/small molecule modifier solutions, showed the capture of trace levels of indium as a result of the chemisorption of these small molecules, suggesting that slow etching of the ITO surface also occurs during the chemisorption event. Conventional aluminum quinolate/bis-triarylamine organic light-emitting diodes (OLEDs) created on ITO surfaces modified with 1, 2, and 3, with and without an overlayer of PEDOT:PSS (a poly(thiophene)/ poly(stryenesulfonate) ITO modifier), showed leakage currents lowered by several orders of magnitude and an increase in OLED device efficiency.
AB - Indium - tin oxide (ITO) surfaces have been modified by chemisorption of carboxylic acid functionalized small molecules: ferrocene dicarboxylic acid (1), 3-thiophene acetic acid (2), and 6-{4-[{4′-[[4-(5-carboxy-pentyloxy)- phenyl]-(4-methoxy-phenyl)-amino]-biphenyl-4-yl}-(4-methoxy-phenyl)-amino] -phenoxy}-hexanoic acid (p-OMe)2-TPD-(C5-COOH) 2) (3). Voltammetrically determined surface coverages of 1-3 increased in two stages, the first stage completing in minutes, the latter stage taking several hours. Electron-transfer rate coefficients, kS, for the probe molecule ferrocene in acetonitrile likewise increased in two stages with increasing surface coverages of 1, 2, and 3. Fourier transform infrared spectroscopy of In2O3 powders, exposed for long periods to ethanol solutions of each modifier, confirmed the formation of indium oxalate-like surface species. X-ray photoelectron spectroscopy of carboxy-terminated alkanethiol-modified gold surfaces, exposed to these same In2O3(powder)/small molecule modifier solutions, showed the capture of trace levels of indium as a result of the chemisorption of these small molecules, suggesting that slow etching of the ITO surface also occurs during the chemisorption event. Conventional aluminum quinolate/bis-triarylamine organic light-emitting diodes (OLEDs) created on ITO surfaces modified with 1, 2, and 3, with and without an overlayer of PEDOT:PSS (a poly(thiophene)/ poly(stryenesulfonate) ITO modifier), showed leakage currents lowered by several orders of magnitude and an increase in OLED device efficiency.
UR - http://www.scopus.com/inward/record.url?scp=33846695061&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33846695061&partnerID=8YFLogxK
U2 - 10.1021/jp064061g
DO - 10.1021/jp064061g
M3 - Article
C2 - 17165963
AN - SCOPUS:33846695061
SN - 1520-6106
VL - 110
SP - 25191
EP - 25202
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 50
ER -