Determination of electroaffinity and ionization potential of conjugated polymers via Fowler–Nordheim tunneling measurements: Theoretical formulation and application to poly(<i>p</i>-phenylene vinylene)

Roman, Lucimara S.; Hümmelgen, Ivo A.; Nart, Francisco Carlos; Péres, Laura O.; Sá, Eduardo L. de

doi:10.1063/1.472947

Cited by 36 publications

(20 citation statements)

References 23 publications

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“…45) interfaces. There is also good agreement with the value e,s = 1.23 eV obtained by Roman et al 46 by means of Fowler-Nordheim tunneling (FNt). However, other equally relevant reports, that are at variance with the above results, exist.…”

Section: Discussionsupporting

confidence: 89%

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Scanning tunneling spectroscopy on organic semiconductors: Experiment and model

et al. 2004

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Scanning-tunneling spectroscopy experiments performed on conjugated polymer films are compared with three-dimensional numerical model calculations for charge injection and transport. It is found that if a sufficiently sharp tip is used, the field enhancement near the tip apex leads to a significant increase in the injected current, which can amount to more than an order of magnitude and can even change the polarity of the predominant charge carrier. We show that when charge injection from the tip into the organic material predominates, it is possible to probe the electronic properties of the interface between the organic material and a metallic electrode directly by means of tip height versus bias voltage measurements. Thus, one can determine the alignment of the molecular orbital energy levels at the buried interface, as well as the single-particle band gap of the organic material. By comparing the single-particle energy gap and the optical absorption threshold, it is possible to obtain an estimate of the exciton binding energy. In addition, our calculations show that by using a one-dimensional model, reasonable parameters can only be extracted from z-V and I-V curves if the tip apex radius is much larger than the tip height. In all other cases, the full three-dimensional problem needs to be considered.

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Section: Discussionsupporting

confidence: 89%

“…3 and 5, and for Refs. [44][45][46]. (ii) The Fermi level is located within a few 100 meV above the HOMO (highest occupied molecular orbital) states.…”

Section: Discussionmentioning

confidence: 99%

Scanning tunneling spectroscopy on organic semiconductors: Experiment and model

et al. 2004

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“…The value of the first onset oxidation potential E' ox of PEA can be detected at 0.15 V vs. Ag/AgCl. This value will be used to calculate the Ionization potential of the PEA (Roman et al, 1998). The multi redox potential was also observed in previously reported work (Schemid et al, 2000).…”

Section: Electrochemical Behavior Of Peasupporting

confidence: 62%

“…Relating electrochemical data, such as the onset oxidation potential (E ' ox ), the onset reduction potential (E ' Red ), and the band gap leads to an understanding of the integrated energy diagram of the film. Onset potentials can be estimated from the intersection of the two tangents drawn at the rising oxidation current curve and the background current curve in the CV using the following formula (Roman et al, 1998):…”

Section: Energy Map Of Peamentioning

confidence: 99%

Photoelectrochemical Studies on CdS/Poly Ethyl-Aniline Interfaces

Kasem¹,

Finley²

2013

IJC

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An inorganic/organic/interface (IOI) consisting of CdS/poly ethyl aniline (PEA) assemblies was subjected to photoelectrochemical studies in nanoparticle suspensions and in thin solid film forms . The effects that PEA modifiers have on the photoelectrochemical behavior of the IOI were investigated using [Fe(CN) 6 ] 4-as a photoactive hydrated electron donor agent. Results show that the adsorption process of [Fe (CN) 6 ] 3-(the photolysis product) controls the photoactivity outcome of IOI assemblies. CdS/PEA shows lower heterogeneous photochemical response than native CdS. Native CdS amorphous nanoparticles adsorb more [Fe(CN) 6 ] 3-with a very steady adsorption/desorption process than the CdS/PEA. The interface activities were explained by analyzing the IOI junction's properties such as electron affinity, work function and hole/electrons barrier heights. The lower hole barrier height versus electron barrier height suggests that charge injection is mediated at the IOI interface through hole transfer. The aqueous nano systems retained moderate stability as indicated by the reproducibility of their photocatalytic activities. Both [Fe(CN) 6 ] 4-and PEA contributed to the stability of native CdS surfaces.

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“…Oscillations around the expected straight line for the F-N model were observed experimentally [5]. Basically, those experiments were done within the regime described above, low voltages and thin polymer layers.…”

mentioning

confidence: 93%